NAVMED P-5010-6.pdf

Bureau of Medicine and Surgery NAVMED P-5010-6 (Rev. 7-2005) Washington, DC 20372-5300 0510-LP-103-9057

Manual of Naval Preventive Medicine

Chapter 6

WATER SUPPLY AFLOAT

DISTRIBUTION STATEMENT "A"

This publication supersedes NAVMED P-5010-6 of 1990 S/N 0510-LP-206-6300

CHAPTER 6

CONTENTS

Section I. Introduction Page

Article 6-1. Scope...........................................................................................6-1 6-2. Responsibilities ...........................................................................6-1 6-3. Shipboard Potable Water ............................................................6-2 6-4. Potable Water Usage Requirement .............................................6-3

Section II. Receipt and Transfer Article 6-5. Receipt and Transfer of Potable Water.......................................6-5 6-6. Approved Sources.......................................................................6-5 6-7. Sources of Doubtful Quality ...................................................... 6-6 6-8. Care of Shipboard Potable Water Hoses and Equipment ...........6-6 6-9. Connection Procedures ...............................................................6-6

Section III. Storage and Distribution Article 6-10. Potable Water Production ...........................................................6-7 6-11. Potable Water Tanks ...................................................................6-8 6-12. Vents and/or Overflow Lines......................................................6-8 6-13. Manholes.....................................................................................6-8 6-14. Measurement of Water Level......................................................6-9 6-15. Filling Lines ................................................................................6-9 6-16. Potable Water Piping ..................................................................6-9 6-17. Repairs ......................................................................................6-10 6-18. Potable Water Tank Coatings ...................................................6-10 6-19. Labeling and Color-Coding ......................................................6-10 6-20. Potable Water Hose Storage Lockers .......................................6-10

Section IV. Disinfection Article 6-21. Disinfection of Potable Water Supplies....................................6-11 6-22. Disinfection of Potable Water Tanks and Systems...................6-15 6-23. Disinfection of Potable Water Hoses, Tapes, and Rods ...........6-16 6-24. Emergency Disinfection of Water for Drinking and Cooking Purposes ...............................................................6-16 6-25. Chlorine Dosage Calculator......................................................6-16 6-26. Required Halogen Residuals.....................................................6-18

Section V. Potable Water, Submarine/Yard Craft Article 6-27. Submarines................................................................................6-19 6-28. Yard Craft .................................................................................6-19

CONTENTS

(Continued)

Section VI. Cargo Water Article 6-29. Emergency Use of Potable Water Tanks for Ballast ................6-21 6-30. Handling of Cargo Water..........................................................6-21 6-31. Temporary Water Tanks ...........................................................6-22

Section VII. Emergency Water Supplies Article 6-32. Battle Dressing Stations............................................................6-25 6-33. Emergency Potable Water, 5-Gallon Containers ......................6-25 6-34. Can and Bottle Drinking Water ................................................6-26

Section VIII. Evaluation of Taste and Odor Problems Article 6-35. General Evaluation of Taste and Odor Problems .....................6-27 6-36. Causes of Taste and Odor in Potable Water .............................6-27 6-37. Indicators of Taste and Odor Problems ....................................6-28 6-38. Initial Evaluation of Taste and Odor Problems.........................6-28 6-39. Control Measures for Taste and Odor Problems.......................6-30 6-40. Request for Outside Assistance ................................................6-30

Section IX. Cross-Connections Article 6-41. General Cross-Connections ......................................................6-33 6-42. Cross-Connection Definitions...................................................6-33 6-43. Improper Piping Installation .....................................................6-34 6-44. Medical Department Cross-Connection Surveillance...............6-34

Section X. Manufacture and Handling of Ice Article 6-45. Manufacture of Ice....................................................................6-37 6-46. Special Precautions for Handling of Ice ...................................6-37 6-47. Cleaning and Disinfecting Ice Machines ..................................6-37 6-48. Bacteriological Quality of Ice ..................................................6-38

Section XI. Water Testing Requirements and Procedures Article 6-49. Scope.........................................................................................6-39 6-50. Temperature and pH Testing ....................................................6-39 6-51. Salinity (Chloride Content).......................................................6-40 6-52. Halogen Residual (Chlorine/Bromine) .....................................6-40 6-53. Bacteriological Collection and Testing.....................................6-44 6-54. Potable Water Log ....................................................................6-45

Section XII. Sample Water Sanitation Bill Article 6-55. Sample Water Sanitation Bill....................................................6-47

Section XIII. References and Appendices Article 6-56. References.................................................................................6-49 6-57. Appendices................................................................................6-51 ii

CHAPTER 6

TABLES Page

Table 6-1. Potable Water Transfer Procedures for Ship-to-Shore and Ship-to-Ship ...........6-6

Table 6-2. Methods for Disinfection of Potable Water Tanks ..........................................6-15

Table 6-3. Chlorine Dosage Calculator for 5% Liquid Sodium Hypochlorite (Unscented) .......................................................................................................6-17

Table 6-4. Chlorine Dosage Calculator for 10% Liquid Sodium Hypochlorite (Unscented) .......................................................................................................6-17

Table 6-5. Chlorine Dosage Calculator for 65-70% Powder Calcium Hypochlorite.........6-18

Table 6-6. Required Halogen Residuals.............................................................................6-18

Table 6-7. Bulk Ice-Making Machine Cleaning/Disinfection Instructions........................6-37

Table 6-8. Ice Dispensing Machine Cleaning/Disinfection Instructions ...........................6-38

Table 6-9. Routine Testing Procedure Summary ...............................................................6-41

LIST OF APPENDICES

Appendix A. Abbreviations ...................................................................................................6-51

Appendix B. Definitions.........................................................................................................6-52

Appendix C. Water Sampling Technique...............................................................................6-53

Appendix D. Sample Potable Water Sanitation Bill...............................................................6-53 iii

MANUAL OF NAVAL PREVENTIVE MEDICINE

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6-1 CHAPTER 6. WATER SUPPLY AFLOAT 6-2

SECTION I. INTRODUCTION

Article Subject Page

6-1 Scope ..............................................................................................................................6-1 6-2 Responsibilities ..............................................................................................................6-1 6-3 Shipboard Potable Water................................................................................................6-2 6-4 Potable Water Usage Requirement ................................................................................6-3

6-1. Scope

a. This chapter provides information for safe and proper potable water handling proced-ures for United States Naval Ships (USNS).

Applicable potable water quality standards are set forth in current Office of the Chief of Naval Operations (OPNAV), Bureau of Medicine and Surgery (BUMED), and Military Sealift Command (MSC) instructions. The basic principles outlined in the following sections will help prevent water-borne disease outbreaks. The use of trademark names in this publication does not imply endorsement by the Department of Navy (DON), but is intended only to assist in identifying specific products.

b. All personnel concerned with loading, treatment, storage, distribution, and medical surveillance of potable water should be familiar with current applicable naval instructions and directives, which supplement this chapter.

6-2. Responsibilities

a. The Naval Sea Systems Command (NAVSEASYSCOM) is responsible for the design, construction, and maintenance of the shipboard potable water systems, including treatment facilities and processes to assure that safe drinking water is available at all times.

b. The Naval Facilities Engineering Command (NAVFACENGCOM) is responsible for promulgating instructions for ship-to-shore potable water connections and for providing potable water from an approved source when the ship is berthed at a naval facility.

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c. Chief, BUMED is responsible for establishing and promulgating health standards for water quality afloat. BUMED will promulgate appropriate instructions, notices, or other publications to reflect afloat water quality requirements. Additionally, BUMED will set forth shipboard requirements for medical surveillance of potable water systems.

d. Area, fleet, and subordinate commanders are responsible for issuing the necessary imple-menting directives to ensure that adequate water sanitation standards are provided and enforced in each ship within the command.

e. The commanding officer, master, or other applicable responsible party of each ship is responsible for promulgating a water sanitation bill to ensure that procedures for receipt, transfer, treatment, storage, distribution, and surveillance are provided and followed.

f. The engineering department of the ship is responsible to the commanding officer or master for implementing the requirements of the NAVSEASYSCOM. This responsibility includes the supply and treatment of potable water and for the system components that receive, store, distribute, produce, and treat potable water. The engineering officer shall ensure that all ship-to-shore connections are made only by authorized shore personnel, when available, or in their absence, ship personnel who are properly supervised by authorized shore personnel; and that all connections required for ship-to-ship potable water transfer are made by personnel trained in handling potable water.

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6-2 MANUAL OF NAVAL PREVENTIVE MEDICINE 6-3

The engineering officer is responsible for the chloride and hydrogen ion (pH) testing of the ship’s potable water. The engineering depart-ment shall ensure minimum halogen residuals are maintained at a potable water tank before placing the tank on-line to the potable water distribution system.

g. The medical department representative (MDR) is responsible for conducting a medical surveillance program of the potable water system including collection of samples for coliform bacteria testing as prescribed and daily halogen residuals from the distribution system.

The MDR shall notify the commanding officer or master of any discrepancies observed in the potable water distribution system.

6-3. Shipboard Potable Water

a. Shipboard potable water primarily comes from approved ashore sources and ships water production plants which include distilla-tion plants or reverse osmosis (RO) plants.

Present water plants aboard naval ships are designed to make the ship as self-sufficient as possible. Generally, ship water treatment plants are capable of producing potable water from bacteriologically contaminated seawater, provided the specific procedures set forth in Chapters 531 and 533 of the Naval Ships Tech-nical Manual (NSTM) are followed. In addition, potable water must be adequately disinfected to maintain the required halogen residual level in the potable water tanks and distribution system.

b. Avoid making water while operating in harbors or from polluted seawater. Seawater shall be assumed polluted when ships are operated in close formation. While making pot-able water, care must be taken not to strip fuel waste tanks or empty bilges forward of the salt-water intakes. Source water in harbors or ship navigation lanes is likely to be contaminated by fuel/oil slicks or other pollutant sources.

Volatile Organic Chemicals (VOCs), which have a lower boiling point than water and which could be present in contaminated unapproved

6-2 source waters, can vaporize and mix with the water vapor during the distillation process, carrying over into the condensate chamber and distillate reservoir.

c. Distilled water tends to be mineral free and can be highly corrosive to metal piping and storage tanks. The leaching of lead and copper from plumbing fixtures and service lines and any other sources in contact with potable water (lead-based paint) is of special concern. Opera-tional checks of shipboard water plants afloat, inspection, and approval of watering points ashore are only a part of the precautions necessary to assure a safe water supply. Many points of possible contamination exist within the ship and may contribute to waterborne disease outbreaks. Therefore, regardless of the source of the water, there must be vigilant surveillance to assure adequate protection from subsequent contamination.

d. Potable Water Sources for Naval Ships:

(1) Distillation, RO, or other NAVSEA approved water production technology.

(2) Shore-to-ship delivery from an approved source.

(3) Shore-to-ship delivery from an unapproved source (when approved source does not exist), refer to Article 6-7.

(4) Ship-to-ship.

e. Potable water is used aboard ship for drinking, cooking, laundry, medical, personal hygiene, and other purposes.

f. Health concerns regarding potable water quality may include physical, chemical, and bacteriological parameters. Direct chemical additives to potable water systems afloat should be tested/certified by the product manufacturer in accordance with National Sanitation Foundation International Standard known as NSF/ANSI Standard 60: Drinking Water Treatment Chemicals – Health Effects.

6-3 CHAPTER 6. WATER SUPPLY AFLOAT 6-4

Likewise, indirect chemical additives to potable water systems afloat should be tested/certified by the product manufacturer in accordance with NSF/ANSI Standard 61: Drinking Water System Components – Health Effects. Manufacturers should meet other applicable NSF/ANSI potable water public health standards as indicated.

g. Use of seawater in food services spaces including sculleries is prohibited and seawater outlets in these spaces must be removed. The dangers of cross connections and of using polluted overboard water cannot be overempha-sized. Cross connections between the potable water and seawater of other systems are not permitted. Exception: specific garbage grinders, which use seawater flush and have been approved by BUMED for use in designated sculleries. Installation of salt water flush garbage grinders precludes storage of clean dishware or other items in the scullery because of concerns for aerosol contamination.

h. Seawater is used aboard ships such as in the fire mains, decontamination, and for marine sanitation devices (MSDs) flushing. Since conservation of potable water is a constant requirement, it is impractical to provide potable water for all purposes.

6-4. Potable Water Usage Requirement

a. Proper indoctrination of the crew and attention to leaks and waste should limit potable water consumption to reasonable amounts.

Water hours may at times become necessary on some ships and this may adversely impact personal hygiene practices. This is particularly applicable to troop-carrying ships loaded beyond their water-producing capacity. Personnel may keep clean and live under sanitary conditions, even with a limited water supply. If unusual conditions require drastic restrictions in the use of potable water, the allowances should not be less than 2 gallons per man per day to be used for drinking and cooking purposes. In hot environments it is necessary to provide sufficient drinking water quantity to prevent heat casualties.

b. For new ship constructions, 50 gallons per day per man is specified by NAVSEA for design considerations. This encompasses a broad spectrum of potable water uses including drinking water, galley and scullery, personal hygiene, and laundry.

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6-4 MANUAL OF NAVAL PREVENTIVE MEDICINE 6-4

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6-5 CHAPTER 6. WATER SUPPLY AFLOAT 6-6

SECTION II. RECEIPT AND TRANSFER

6-5 Receipt and Transfer of Potable Water ..........................................................................6-5 6-6 Approved Sources ..........................................................................................................6-5 6-7 Sources of Doubtful Quality ..........................................................................................6-6 6-8 Care of Shipboard Potable Water Hoses and Equipment...............................................6-6 6-9 Connection Procedures...................................................................................................6-6

6-5. Receipt and Transfer of Potable Water

a. When receiving or transferring potable water via approved sources, proper procedures must be followed to prevent contamination.

(1) A free available chlorine (FAC), chloramines (total chlorine), or total bromine residual as applicable shall be completed prior to the initial transfer of water.

(2) If water taken aboard the ship does not have the required halogen residual, the ship must boost halogen residual, or have shore facility boost halogen residual in source water to obtain the proper residual.

(3) When potable water from the trans-ferring source contains the proper halogen residual, no further treatment is required.

b. Potable water connections between shore and ships must be made or supervised by authorized shore station personnel. In the event shore personnel are unavailable, properly trained ship personnel will complete this responsibility.

The individual making the potable water hose connections shall ensure hoses are not connected to a non-potable system. Engineering will notify the MDR prior to making potable water hose connections. The MDR shall determine if the correct halogen residual is present in the source water and if it is not, he or she must notify the engineering department representative.

c. Potable water hoses shall not be sub-merged in harbor water.

6-6. Approved Sources. Potable water may be received from approved shore facilities or other vessels. The following are approved potable water sources:

a. Environmental Protection Agency (EPA) (State and territory) approved public water systems.

b. Approved U.S. military sources including establishments under the cognizance of the British Royal Navy, Canadian Forces, and the Royal Australian Navy. These sources are subject to termination or modification. See the current American-British-Canadian-Australian Naval Quadripartite Standardization Agreement Program, ABCA NAVSTAG 23, Quality Stand-ards for Potable Water. Under certain emergency or wartime situations, shore water sources may be under the cognizance of Quadripartite Standardi-zation Agreement 245, Edition 2, of the American-British-Canadian-Australian Armies Standardization Program, Minimum Require-ments for Water Potability (Short and Long Term Use) or the NATO Standardization Agreement, STANAG 2136, Minimum Requirements of Water Potability for Short Term Issue.

c. OCONUS water source information may be obtained from U.S. military representa-tives ashore or Navy Environmental Preventive Medicine Units (NAVENPVNTMEDUs) having area responsibility.

d. Bottled water must be obtained from DOD approved sources.

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6-7 MANUAL OF NAVAL PREVENTIVE MEDICINE 6-9

6-7. Sources of Doubtful Quality. All water supplied by public or private systems not listed in Article 6-6 should be considered of doubtful quality. When doubt exists as to the quality of water, the MDR, or a responsible officer must investigate the source and examine the water as thoroughly as possible with the means available;

he or she must then advise the commanding officer or master relative to necessary proced-ures, safeguards, and disinfection. In instances where the ship must receive water of doubtful quality, disinfection will be accomplished in accordance with Article 6-21.

6-8. Care of Shipboard Potable Water Hoses and Equipment

a. Potable water hoses shall not be used for any other purpose. They must be properly labeled, stored, and protected from sources of contamination at all times. They must be examined routinely and removed from use when cracks develop in the lining or leaks occur.

Disinfection procedures for potable water hoses are found in Articles 6-9 and 6-23.

b. Shipboard potable water risers shall be at least 18 inches above the deck and turned down, except when risers are located within the ship, such as in submarines. Potable water riser must be properly labeled and fitted with a cap and keeper chain. Potable water riser valve or valve handles must be properly color coded in accordance with NSTM Chapter 505. Riser hose connections shall be disinfected prior to connection.

c. Potable water tank sounding tubes will be equipped with screw caps attached to keeper chains. Screw caps will be secured with a lock.

On those ships with sounding rods, the rod should remain in the tube at all times. Potable water sounding tapes must be sanitized prior to each use and shall only be used for potable water tank volume measurements.

6-9. Connection Procedures. Table 6-1 provides guidelines for connection procedures covering ship-to-shore and ship-to-ship transfer of potable water. Modification of these procedures may be necessary or required due to ship configuration or operating conditions.

Table 6-1. Potable Water Transfer Procedures for Ship-to-Shore and Ship-to-Ship*

Ship-to-Shore Ship-to-Ship

Remove shore cap and flush pier side potable water outlet for 15-30 seconds. Immerse outlet and rinse fitting in solution containing 100-ppm FAC (free available chlorine) for at least 2 minutes. Flush water to waste for 15-30 seconds.

Both ships disinfect their respective potable water riser connections. The leading potable water hose shall have the hose cap in place during the high-line procedure.

Deliver a clean disinfected potable water hose to the outlet just before the connection is made (potable water hoses should be provided by the shore facility). Remove hose caps or uncouple hose ends and disinfect if not previously disinfected. Connect hose to pier side outlet and flush.

When the receiving ship secures the potable water hose, the cap is removed and the hose coupling is disinfected.

Disinfect shipboard riser connections with 100-ppm FAC solution. Connect hose to the potable water shipboard riser and deliver potable water. Other FDA listed food contact surface disinfectants such as iodine may be used if approved by the MDR.

The supplying ship connects its end and flushes the hose.

When the transfer is completed, secure the shore water source; remove the ship connection, then the shore connec-tion. Thoroughly flush the potable water outlet and recap.

When the transfer is completed, the receiving ship removes the potable water hose and replaces the caps on the receiving connection and the potable water hose.

Drain the potable water hose thoroughly and properly store in the potable water hose storage locker.

The supplying ship then retrieves, couples or caps, and properly stores the potable water hose.

*Tables read top to bottom, not left to right.

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6-10 CHAPTER 6. WATER SUPPLY AFLOAT 6-10

SECTION III. STORAGE AND DISTRIBUTION

6-10 Potable Water Production .............................................................................................. 6-7 6-11 Potable Water Tanks...................................................................................................... 6-8 6-12 Vents and/or Overflow Lines......................................................................................... 6-8 6-13 Manholes ....................................................................................................................... 6-8 6-14 Measurement of Water Level ........................................................................................ 6-9 6-15 Filling Lines................................................................................................................... 6-9 6-16 Potable Water Piping ..................................................................................................... 6-9 6-17 Repairs ......................................................................................................................... 6-10 6-18 Potable Water Tank Coatings ...................................................................................... 6-10 6-19 Labeling and Color-Coding ......................................................................................... 6-10 6-20 Potable Water Hose Storage Lockers .......................................................................... 6-10

6-10. Potable Water Production

a. Types of Water Production Plants

(1) Distillation plants. Installed on naval vessels are three general types, depend-ing on the source of heat used to evaporate seawater.

(a) Steam distilling plants are operated by steam supplied directly or indirectly from a power plant or auxiliary boiler. They are subdivided into two groups, submerged type and flash type. These subdivisions differ mainly in the pressure in the heating elements and evaporator shell.

(b) Waste heat distilling plants are submerged tube type and use heat derived from diesel engine jacket water.

(c) Vapor compression type distill-ing plants require primarily only electrical energy for operations; however, additional heat exchangers that use waste heat (exhaust gas or cooling water) may be installed.

(2) Reverse osmosis (RO). Single and triple pass RO plants are another type of shipboard water production technology. RO consists of a pre-filtration section that typically includes, in surface ships, a coarse strainer, a centrifugal separator and cartridge filters that remove suspended particles as small as 1 micron in some cases. Triple pass RO plants used for submarines do not have a separator but are fitted with cartridge filters nominally rated at 3 micron to remove suspended particles. The RO water treatment technology in lieu of distillation will likely be the technology of choice for fresh water production for new construction ships. A brief discussion of RO treatment is below.

(a) Through a high-pressure pump, the filtered water is then boosted up in pressure to as much as 1000 psi where it is introduced into the RO pressure vessels that contain circularly wrapped polyamide thin film RO membranes. A portion of the filtered water, typically 20-25 percent, permeates through the membrane to become fresh water. The remaining brine, which does not pass through the RO membrane, is dis-charged from the RO unit as waste.

(b) Although the RO membrane is theoretically capable of removing all viruses and bacteria from the source water under optimal operating conditions, membrane fouling does occur and can compromise the integrity of the membranes. Reverse osmosis is not solely relied upon for accomplishing pathogen removal in single pass RO plants thus additional disinfection such as chlorination or bromination is required.

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6-10 MANUAL OF NAVAL PREVENTIVE MEDICINE 6-13

(c) In triple pass RO plants addi-tional disinfection requirement is waived because it is assumed that the redundancy of three membranes, connected in series, would accomplish adequate removal of pathogenic organisms. Triple pass RO water quality is comparable to distilled water and often may be better.

b. NSTM Chapter 533, Potable Water Systems (1995), and NSTM Chapter 531, Desalination, Volume 3 Reverse Osmosis Desalination Plants (1999), RO treated water from a single pass RO unit ranges in purity from 350 to 500 ppm Total Dissolved Solids (TDS), while distilled water purity is on the order of 1 to 2 ppm TDS and a third pass RO unit can produce water with less than 1.0 ppm TDS.

Low TDS distilled water and multi pass RO water can be more corrosive to plumbing and storage tanks than single pass RO water. In addition, water high in dissolved gasses (e.g., carbon dioxide and oxygen), after multiple passes through RO membranes, can also be corrosive.

c. Although potable water production/ treatment is an engineering responsibility, the MDR must be cognizant of the process to ade-quately provide surveillance and recommenda-tions.

6-11. Potable Water Tanks

a. The construction and location of pot-able water tanks should prevent contamination of the water. For full utilization of space, potable water is stored on most ships in inner bottom tanks, other skin tanks, and peak tanks.

The ship bottom, which serves as the outer shell of the inner bottom tanks, is subjected to maxi-mum external pressure from water that may be heavily polluted, and is vulnerable to leakage.

The plating over the inner bottom tanks often serves as the deck in machinery spaces. Inner bottom and other skin tanks may have common bulkheads with ballast tanks, fuel tanks, or other

6-8 storage spaces. These potential sources of contamination make it necessary to devote careful attention to maintaining the quality of water stored in skin tanks, particularly those located in inner bottoms.

b. Potable water tanks should not be filled with ballast water unless absolutely necessary for the survival of the ship. When non-potable liquid (water) is introduced into potable water tanks, all tanks, lines, fittings, and pumps must be discon-nected from the potable water system, plugged or capped, and not reconnected until adequately cleaned, flushed, disinfected, and tested as applicable in accordance with Article 6-22.

Cross connections between potable and non-potable water must be prevented for force health protection.

6-12. Vents and/or Overflow Lines. Vents and/or overflow lines provided on potable water tanks will be located to reduce the possibility of contamination. The openings must be screened with 18-mesh or finer non-corrosive metal wire.

They must not terminate in food service, medical, toilet, or other spaces where contamination or odors may be transmitted to the water, nor in any space where electrical or electronic equipment is located. In no instance will potable water tanks vent outside the ship.

6-13. Manholes. The construction and location of manholes should minimize the possibility of contamination. If a manhole is located on the side of the tank, flush-type construction is accept-able. If located on the top (including the deck, if the deck forms the top of the tank), a coaming or curb rising at least one-half inch above the top of the tank must be provided and the manhole cover must extend to the outer edge of the curb or flange. The cover must have an intact gasket and a device for securing it in place. Normally, man-holes not exposed to the weather decks are fitted with the flush-type manhole cover or the raised, bolted-plate cover. The latter is preferable for potable water tanks.

6-14 CHAPTER 6. WATER SUPPLY AFLOAT 6-16

6-14. Measurement of Water Level

a. There are several methods for measure-ment of water volume in tanks including auto-matic level gauges, petcocks, and sounding tubes. Many ships have more than one system.

On those ships with sounding rods, when not in actual use, the rod should remain in the sound-ing tube at all times. On those ships using steel tapes, the tapes must be sanitized prior to each use, stored in a sanitary manner, and used only for potable water measurements in accordance with Article 6-23.

b. Soaking the entire tape apparatus in a solution of 100-ppm FAC (free available chlorine) solution for 2 minutes may be used to sanitize potable water sounding tapes. Another method, which can be used, involves wiping the tape with clean gauze soaked in an approved disinfectant solution such as food service contact surface disinfectant in accordance with Article 6-23, such as iodine (Wescodyne) disinfectant or alcohol swab.

6-15. Filling Lines

a. Potable water lines/piping must never be cross connected to any non-potable piping or system. Where a common line is used to load and distribute potable water to non-potable tanks, the delivery to the non-potable tanks must be through an air gap or approved and appro-priate backflow prevention device. Filling lines that have common piping arrangement for directing potable water from an approved source to non-potable water systems by means of valves or interchangeable pipe fittings are not acceptable.

b. Filling connections (hose valves) must be clearly labeled and color-coded in accord-ance with NSTM Chapter 505. They will be secured with screw caps attached with keeper chains in accordance with Article 6-8.

c. Filling connection hose valves must have the potable water receiving connection at least 18 inches above the deck and turned down to protect it from contamination following Article 6-8.

6-16. Potable Water Piping

a. Special attention must be given to potable water piping located in the bilge area, particularly the piping on the suction side of the potable water pumps where leakage could result in contamina-tion. This piping should be hydrostatically tested in accordance with the preventive maintenance system, and kept in sound material condition.

b. Shipboard design specifications stipulate potable water piping through non-potable tanks and piping non-potable liquid through potable water tanks must have the pipe surrounded by sloped self-draining pipe tunnel.

c. Ensure adequate air gap or approved backflow prevention device is provided between the potable water outlet and a non-potable water system, fixture, or machine. Article 6-42 pro-vides more information on cross connection control.

d. All potable water pumps should be air-tight and free from cross connections. Non-potable water should never be used for priming pumps or maintaining packing gland seals. Pumps that have been dismantled for repair must be disinfected after reassembly prior to being returned to service.

e. To avoid scald injuries, the temperature setting for the hot water heaters serving habit-ability space showers and lavatories must be set not to exceed 120°F at the water tap. Hot water heaters serving other areas such as the galley (Gaylord Hoods), laundry, etc., are set at appropriately higher temperatures.

f. Point of use potable water treatment devices such as charcoal impregnated or other filter equip-ment use are generally not recommended. Only NSF certified point of use devices shall be used.

These devices remove required trace halogen resid-ual from the potable water and defeat the purpose of residual halogen protection. In addition, charcoal filtration devices can promote bacterial growth, especially when not used on a daily basis or when not changed at proper intervals. Point of use water treatment devices shall be used and maintained in accordance with the manufacturer’s directions.

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6-17 MANUAL OF NAVAL PREVENTIVE MEDICINE 6-20

6-17. Repairs

a. In the event of a break or compromise in the potable water system, or a potable water tank is entered for any reason, all involved tanks, parts, and lines must be cleaned, flushed, and disinfected prior to returning the system to use. The MDR must be notified of the break or entry and the disinfection procedure accomp-lished by the engineering department.

b. For potable water piping repairs including flanged joints, only sealants and lubricants certified to NSF/ANSI Standard 61 shall be used. Confirmation concerning authorized sealants and lubricants may be obtained by contacting NAVSEASYSCOM.

6-18. Potable Water Tank Coatings

a. Only potable water tank coatings that are listed within NSTM Chapter 631 and NSF/ANSI Standard 61 are approved for use.

Taste and odor problems with water quality are often associated with improper application and curing procedures. Paint thickness, the touch-up material, ventilation, temperature, humidity, curing time, etc., are important application factors that can contribute to taste and odor complaints. Taste and odor are further discussed in Section VIII.

b. The shipyard or contractor may wish to complete potable water taste/odor testing, after construction or repair of potable water tanks.

Water taste complaints are not uncommon from ships which have undergone recent potable water tank painting.

6-19. Labeling and Color-Coding

a. Potable water sounding tubes will be clearly labeled with an identification plate. The sounding tube cap will be color-coded dark blue.

On ships using steel tapes for sounding potable water tanks, the tape handle must be color-coded dark blue, labeled, or otherwise identified

“POTABLE WATER USE ONLY."

b. Valves for receiving or supplying potable water must be conspicuously designated by a warning plate bearing the inscription “POTABLE WATER ONLY" in ¼ inch high letters.

c. Potable water hoses must be labeled “POTABLE WATER ONLY" with 1-inch high letters approximately every 10 feet and the end couplings painted dark blue in accordance with NSTM Chapter 505.

d. Potable water piping passing through any given space must be appropriately labeled to indicate the type of service and with an arrow indicating the direction of the flow.

6-20. Potable Water Hose Storage Lockers.

Potable water hose storage lockers must be identified and labeled "POTABLE WATER HOSE." When not in use, potable water hoses must be coupled or capped and stored in designated lockers. The lockers must be vermin proof, locked, and be elevated at least 18 inches off the deck when located on weather decks and sponsons. Printed instructions outlining step-by-step methods for disinfection of potable water hoses and risers must be posted in a conspicuous location inside the hose storage locker in accordance with Article 6-55, Sample Water Sanitation Bill.

6-10 25 Jul 2005

6-21 CHAPTER 6. WATER SUPPLY AFLOAT 6-21

SECTION IV. DISINFECTION

6-21 Disinfection of Potable Water Supplies....................................................................... 6-11 6-22 Disinfection of Potable Water Tanks and Systems...................................................... 6-15 6-23 Disinfection of Potable Water Hoses, Tapes, and Rods .............................................. 6-16 6-24 Emergency Disinfection of Water for Drinking and Cooking Purposes ..................... 6-16 6-25 Chlorine Dosage Calculator......................................................................................... 6-16 6-26 Required Halogen Residuals........................................................................................ 6-18

6-21. Disinfection of Potable Water Supplies

a. General

(1) Disinfection of water is required to ensure the destruction of pathogenic organ-isms. Maintenance of a halogen residual is the usual method of guarding against contamination or accidents that may occur during the produc-tion, handling, storage, and distribution of potable water. The absence of a Free Available Chlorine (FAC) or total bromine residual (TBR) in the ship's potable water may indicate contamination.

The presence of a halogen residual provides a safety factor but does not correct unsanitary practices or conditions. FAC residual concentrations as high as 1.0 ppm at the tap usually do not cause objection-able tastes and odors, but where certain organic substances are present, very small concentrations of combined chlorine or bromine can produce undesirable tastes or odors. These undesirable tastes and odors do not affect the safety (potability) of water but may impact palatability (taste) of water, thus discourage water consumption. While the National Primary Drinking Water Standards are not applicable for shipboard potable water systems, EPA has established a maximum contaminant level (MCL) for all disinfectants at 4 ppm.

(2) All water has some halogen demand which is the amount of chlorine or bromine used through reaction with substances present in the water. Shipboard water is disinfected by the addition of sufficient chlorine or bromine to produce not less than 0.2 ppm FAC or TBR after 30 minutes contact time measured at the potable water tank. The amount of chlorine or bromine required to produce a FAC or TBR of not less than 0.2 ppm after 30 minutes can vary widely because of halogen demand, water temperature, and other factors. Again, these chemical reactions may impact water palatability.

(3) Halogen types. Chlorine and bromine are approved methods for disinfecting shipboard potable water. Mechanical methods of treatment are preferable to chlorine batch treat-ment procedures. Batch chlorination procedures are less reliable, require greater time and effort, and are generally less effective. Many municipal water sources use chloramine for disinfection which needs to be considered when doing halogen testing pier side. Chlorine or bromine can be added to chloramine treated municipal water.

(a) Chlorine

1. Chlorine is available for shipboard use as calcium hypochlorite (HTH 65-70% available chlorine), 6-ounce bottle, a granular solid or sodium hypochlorite in varying strengths, as a liquid. Common household bleach (unscented) is a 5.25% solution of sodium hypo-chlorite. HTH is most frequently used because of its relatively long shelf life and reduced storage space requirements. However, it should be noted that HTH presents a potential personnel and fire hazard due to its corrosiveness and chemically active nature. This material is classified as hazardous and requires special storage pre-cautions and shall be handled and stowed in accordance with NSTM, Chapter 670.

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6-21 MANUAL OF NAVAL PREVENTIVE MEDICINE 6-21

Contact between HTH and oxidizable material may result in spontaneous combustion (fire).

HTH should be obtained in 6-ounce containers and stored in a cool, dry, well-ventilated place where there is no danger of contact with oxidiz-able materials. Calcium or sodium hypochlorite will lose strength gradually with age and more rapidly when opened or stored in hot spaces or sunlight.

2. The ready use stock of 6-ounce HTH bottles issued to the engineering department must be stowed in a locked box mounted on a bulkhead, preferably in the depart-ment office space. Under no circumstances is the box to be installed in a machinery space, flam-mable liquids storeroom, paint locker, berthing space, storeroom, or in the oil and water test laboratory areas. A metal box, such as a first aid locker, is recommended for this purpose. Vent holes (such as three 1/4 inch holes) shall be drilled in the bottom of the box to allow release of any chlorine products. No more than a 7-day supply shall be maintained in ready use stock at any time.

3. Storeroom stocks of HTH must be stowed in labeled, ventilated lockers or bins. The lockers or bins must be located in an area where the maximum tempera-ture will not exceed 100°F (37.8°C) under normal operating conditions and is not subject to condensation or water accumulation. The area must not be adjacent to a magazine and the lockers or bins must be located at least 5 feet from any heat source or surface, which may exceed 140°F (60°C). They must not be located in an area used for stowage of paints, oils, grease, or other combustible organic materials. No more than forty-eight 6-ounce bottles shall be stowed in any individual locker or bin. Issue will be made only to personnel designated by the MDR or engineering officer.

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4. All lockers, bins, and enclosures containing HTH must be labeled with red letters on a white background, (HAZARD-

OUS MATERIAL, CALCIUM HYPOCHLO-

RITE).

5. Electrolytic disinfectant generator (EDG) uses brine electrolysis chemical process to produce a sodium hypochlorite solu-tion (FAC) for injection. Chemical additives, including salt shall be certified to NSF/ANSI Standard 60.

(b) Bromine. Bromine is pro-vided by a bromine impregnated resin cartridge, which is classified as slightly corrosive and requires proper handling and storage procedures.

Bromine cartridges must be stored in a clean, dry, ventilated storeroom. Bromine storage lockers require a hazardous warning plate described, in NSTM Chapter 533, Figure 6. Bromine cart-ridges have a shelf life of 2 years from the date of manufacture. Cartridges exceeding the shelf life can still be used, but chemical disinfection efficiency may be reduced.

b. Mechanical Methods of Disinfection

(1) Naval vessels use several types of chlorinator installations. Chlorinators may be installed in the distilling plant, distillate line, and the shore fill line. The chlorinator may also serve both the distillate line and the shore fill line.

(a) The distillate line is generally provided with an electric, motor-driven chlorinator. These chlorinators will have controls, which energize the chlorinator in conjunction with the distillate pump motor and water flow past the chlorinator.

(b) The shore fill line is generally provided with a hydraulically actuated chlorinator or an electrical motor driven chlorinator. The hydraulically actuated unit injects hypochlorite solution into the water system in proportion to the flow of water through a meter.

6-21 CHAPTER 6. WATER SUPPLY AFLOAT 6-21

(c) The distillate line and the fill line may be served by a fill line chlorinator unit if the distilling plant is large enough to permit sufficient flow through the unit. This type of installation is generally provided with a hydraulically actuated or an electric motor-driven chlorinator.

(2) Bromine treatment installations use two types of brominators. One type is used on the discharge line and the other is used to recirculate water in the potable water tanks during treatment.

(a) The in-line (proportioning) brominator is used when the desalination unit is online and making water. Multiple vendors manufacture these devices. Dependent on design, the unit is either provided with a set of orifices that gauges a predetermine proportion of flow through a bromine cartridge or via a throttle valve design which controls flow. In line brominator units contain an orifice preset to deliver 0.7 ppm bromine to the water during normal operating procedures and an orifice to deliver 2.0 ppm bromine to the water when an increase in total bromine is required as detailed in Article 6-21a(3)(b). The throttle valve design also allows for adjustment of bromine feed.

Bromine is washed from the cartridge into the bypassed water stream. One in-line brominator is required for each water plant.

(b) The recirculation brominator unit is designed to boost bromine residual for water in a potable water tank. Treatment is accomplished by the recirculation of potable water from a potable water tank through the brominator and back to the same tank. This treatment offers diversity in recirculation and bromination of water received from external water sources as well as providing capability to boost bromine levels from ship produced water when necessary. As the water in a selected tank is recirculated, a portion of the recirculated water is automatically proportioned to flow through the bromine cartridge. A timing device to achieve the required bromine feed into the selected tank limits flow through the cartridge.

After a pre-calculated period of time, the timing device terminates the bromine feed into the water. Recirculation of water continues for an additional pre-calculated time period to complete an even dispersion of bromine through the tank.

These time period calculations are based on individual tank volume and temperature of the water. This recirculation unit is also preset to deliver 0.7 ppm bromine to the water being recirculated. A sampling tap is present to test the bromine residual after recirculation; if the desired level of bromine has not been achieved through the initial recirculation process, the timer may be reset and the water recirculated until the desired level of TBR is achieved; however, efforts to achieve bromine levels at the 2.0 or higher ppm level may not be practical due to the length of time required. It may be more convenient to use batch chlorination procedures to rapidly raise the levels of chlorine in the water supply, particularly in the event of contamination or necessity to achieve higher chlorine levels.

(3) The batch chlorination method of disinfection may be used if mechanical methods for treatment are not available. However, this is considered the least desirable method of disinfect-ing a potable water tank because it may result in over-chlorination due to the inability to properly mix the water and hypochlorite solution. The proper dosage of chemical must be determined for the volume of water to be disinfected. Article 6-25 provides guidance for determining the chlorine dosage. When 65-70% strength HTH is used, the calculated amount is dissolved in a non-glass container of warm water (80°F to 100°F) and the suspended matter is allowed to settle out. Only the clear fluid (supernatant) is introduced into the sounding tube when the tank is about 1/4 full, add 1 gallon of potable water to flush the sounding tube.