Originally Posted by Intifada
First of all, can I add bleach to a full SS water tank? If so how many ml of bleach per litre of water? Thanks.
Here is a Practical Sailor note on the subject I copied to my computer years ago:
There is a standard sanitizing procedure for recreational vehicles (ANSI A119.2 section 10.8) that works just as well for boats. We've added a few details, but the bones of it come straight from the code and have been reviewed and accepted by the U.S. Public Health Service
• Turn off the hot water heater
• Remove any carbon canisters or micron rated filters. Remove any faucet aerator screens. Wire mesh pump
protection strainers should stay in place. The plumbing
will very likely slough off a layer of bacteria during later flushing
• Clean and remove the vent screen
and flush the vent hose.
• Use either following methods to determine the amount of common household bleach needed to sanitize the tank.
1. Multiply gallons of tank capacity by 0.13; the result is the ounces of bleach needed to sanitize the tank. This is 1/8 cup of plain bleach (no fragrance) per 10 gallons.
2. Multiply liters of tank capacity by 1.0; the result is the milliliters of bleach needed to sanitize the tank.
• Mix the proper amount of bleach within a 1-gallon container of water. This will provide better mixing and reduce spot corrosion
• Pour the solution (water/bleach) into the tank and fill the tank with potable water.
• If possible, allow some solution to escape though the vent. (If the vent is exterior, prevent any spillage into local waters.) This will sanitize the vent line.
• Open all faucets (hot and cold) allowing the water to run until all air is purged and the distinct odor
of chlorine is detected. Leave the pressure pump
• The standard solution must have four hours of contact time to disinfect completely. Doubling the solution concentration reduces the contact time to one hour.
• When the contact time is completed, drain the tank. Refill with potable water and purge the plumbing of all sanitizing solution. Repeat until bleach is no longer detectable.
• If the smell of bleach persists after two refill and drain cycles, add a teaspoon of hydrogen peroxide per 20 gallons and mix. The peroxide will oxidize the hypochlorite to chloride (salt) and oxygen, neutralizing the bleach. Any excess peroxide will be harmless to drink and will have no taste. Peroxides are common ingredients in commercially available water freshening preparations like those we tested. Don't use vinegar, which can ferment, undoing all of your hard work
• Replace all filters and the vent screen
• Note for aluminum
tanks: Some sailors are afraid of using bleach in aluminum tanks for fear of rapid corrosion
. This shouldn't be a concern for infrequent cleaning
when the recommended dosage and time is observed. As an alternative, we found PuriClean to be an effective sanitizer, and it was non-corrosive toward aluminum.
Part One of Frye's three-part series on onboard water quality, a test of water tank pre-filters, began in the June 2015 issue; the July 2015 issue focuses on keeping water clean and fresh; look for part three in the August 2015 issue. You can follow Frye's other experiments and sailing adventures at Sail Delmarva