I have a friend with a Hunter 27 (1980 vintage) sailboat. It has a central water tank - pressurized. His question is - how can he keep his water tank 'clean' - drinkable in the summer? I recommended bleach - but I don't know the proper concentration of bleach to water. Any recommendations? Tom Grass Grasshopper II H-26 #174
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Sanitizing Instructions From Shurflo
SANITIZING Potable water systems require periodic maintenance to deliver a consistent flow of fresh water. Depending on use and the environment the system is subject to, sanitizing is recommended prior to storing and before using the water system after a period of storage. Systems with new components, or ones that have been subjected to contamination, should also be disinfected as follows: 1. Use one of the following methods to determine the amount of common household bleach needed to sanitize the tank. A) Multiply "gallons of tank capacity" by 0.13; the result is the ounces (oz.) of bleach needed to sanitize the tank. B) Multiply "Liters of tank capacity" by 1.0; the result is the milliliters of bleach needed to sanitize the tank. 2. Mix into solution the proper amount of bleach within a container of water. 3. Pour the solution (water/bleach) into the tank and fill the tank with potable water. 4. Open all faucets (HOT&COLD) allowing the water to run until the distinct odor of chlorine is detected. 5. The standard solution must have four (4) hours of contact time to disinfect completely. Doubling the solution concentration allows for contact time of one (1) hour. 6. When the contact time is completed, drain the tank. Refill with potable water and purge the plumbing of all sanitizing solution. NOTE: The sanitizing procedure outlined above is in conformance with the approved procedures U.S. Public Health Service.
SANITIZING Potable water systems require periodic maintenance to deliver a consistent flow of fresh water. Depending on use and the environment the system is subject to, sanitizing is recommended prior to storing and before using the water system after a period of storage. Systems with new components, or ones that have been subjected to contamination, should also be disinfected as follows: 1. Use one of the following methods to determine the amount of common household bleach needed to sanitize the tank. A) Multiply "gallons of tank capacity" by 0.13; the result is the ounces (oz.) of bleach needed to sanitize the tank. B) Multiply "Liters of tank capacity" by 1.0; the result is the milliliters of bleach needed to sanitize the tank. 2. Mix into solution the proper amount of bleach within a container of water. 3. Pour the solution (water/bleach) into the tank and fill the tank with potable water. 4. Open all faucets (HOT&COLD) allowing the water to run until the distinct odor of chlorine is detected. 5. The standard solution must have four (4) hours of contact time to disinfect completely. Doubling the solution concentration allows for contact time of one (1) hour. 6. When the contact time is completed, drain the tank. Refill with potable water and purge the plumbing of all sanitizing solution. NOTE: The sanitizing procedure outlined above is in conformance with the approved procedures U.S. Public Health Service.
My theory on water tanks is.
Use the water to shower, wash and only on an emergency to drink. To cook and drink I use bottled water. If bottled water is not available we will boil water destined for consumption. Water does and will go bad. Tank water used in small amounts, for coffee or for cooking is not likely to make you sick but why take a chance of ruining your trip or vacation. Marine heads and diahrea are not the best of friends. The water that we put in the tank is city water which has been treated, we are aware that chloine and the other chemicals used loose their effectiveness with time. I don't have the time to calculate or keep track of the amount of left over water in the tank and for how long it has been there before I top off the tank before a trip. I would not want to exceed amount of chemicals in the water. Let's say that I have had more than my share of stomack maladies due to impure waters. I'm not saying bottle water is 100% safe because is not but chances are it will be fresher.
Use the water to shower, wash and only on an emergency to drink. To cook and drink I use bottled water. If bottled water is not available we will boil water destined for consumption. Water does and will go bad. Tank water used in small amounts, for coffee or for cooking is not likely to make you sick but why take a chance of ruining your trip or vacation. Marine heads and diahrea are not the best of friends. The water that we put in the tank is city water which has been treated, we are aware that chloine and the other chemicals used loose their effectiveness with time. I don't have the time to calculate or keep track of the amount of left over water in the tank and for how long it has been there before I top off the tank before a trip. I would not want to exceed amount of chemicals in the water. Let's say that I have had more than my share of stomack maladies due to impure waters. I'm not saying bottle water is 100% safe because is not but chances are it will be fresher.
You "drink" more of your tank water than you think
You wash your hands in it, then pick up a sandwich...rinse out a cup or glass with it, then put your bottled water in the glass...wash your face, including your lips in it...etc. So if it hasn't made you sick yet, it's safe to drink. If you read the instructions that Greg posted again, you'll see that you don't ADD the bleach to the tank water, you fill the tank with that solution (an easier way to calculate it is 1 pint bleach/25 gal of water)...let it stand for at least 24 hours, then flush it all out and refill the system with water. Those instructions are almost identical to those I've posted here for years (also included in my book, see link below)...with a couple of exceptions: Do NOT leave the solution in the system for more than 24 hours....leave the water pump on to keep the system pressurized so that the solution remains in the plumbing...'cuz 90% of funky water is caused by molds etc that grow in the plumbing while the boat sits with the pump off....if any taste/smell of chlorine remains after flushing the solution out of the system, fill the tank with 1 quart of distilled white vinegar/50 gals of water...turn on the faucets to get that into the plumbing...go out and tack a lot...then drain and refill with water. Recommissioning the system annually or semi-annually using this method should keep your water smelling and tasting as good--and as safe--as any that comes out of a faucet on land. If you need to improve on that, install a filter in the galley faucet. Just remember that filters not a substitute for tank maintenance, but in addition to it, and that filters need regular cleaning or replacement. Finally, the same critters that thrive in your boat's plumbing thrive even better in pipes and hoses sitting in the warm sun...so before filling the tank each time, let the water run till all the water that's been standing in the dock supply line and your own hose has been flushed out.
You wash your hands in it, then pick up a sandwich...rinse out a cup or glass with it, then put your bottled water in the glass...wash your face, including your lips in it...etc. So if it hasn't made you sick yet, it's safe to drink. If you read the instructions that Greg posted again, you'll see that you don't ADD the bleach to the tank water, you fill the tank with that solution (an easier way to calculate it is 1 pint bleach/25 gal of water)...let it stand for at least 24 hours, then flush it all out and refill the system with water. Those instructions are almost identical to those I've posted here for years (also included in my book, see link below)...with a couple of exceptions: Do NOT leave the solution in the system for more than 24 hours....leave the water pump on to keep the system pressurized so that the solution remains in the plumbing...'cuz 90% of funky water is caused by molds etc that grow in the plumbing while the boat sits with the pump off....if any taste/smell of chlorine remains after flushing the solution out of the system, fill the tank with 1 quart of distilled white vinegar/50 gals of water...turn on the faucets to get that into the plumbing...go out and tack a lot...then drain and refill with water. Recommissioning the system annually or semi-annually using this method should keep your water smelling and tasting as good--and as safe--as any that comes out of a faucet on land. If you need to improve on that, install a filter in the galley faucet. Just remember that filters not a substitute for tank maintenance, but in addition to it, and that filters need regular cleaning or replacement. Finally, the same critters that thrive in your boat's plumbing thrive even better in pipes and hoses sitting in the warm sun...so before filling the tank each time, let the water run till all the water that's been standing in the dock supply line and your own hose has been flushed out.
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