Newsgroups wrote:
After rinsing the residual antifreeze out of my sailboat fresh water system
extensively, I filled the (~100 gallon stainless) tanks through a simple
carbon filter. Only a few weeks later, the water coming out the galley and
head sinks, cold or hot, has a definite sulfur odor. What are the best
treatments for fresh water system "purification"? Are they all
one-time-through-and rise-out approaches, or are there safe, non-toxic
things that can be left in the water as well?

This should do the trick:

Although most people think only in terms of the tank, the plumbing is
actually the source of most foul water, because the molds, mildew, fungi
and bacteria which cause it thrive in damp dark places, not under water.
Many people—and even some boat manufacturers—believe that keeping the
tanks empty reduce the problem, but an empty water tank only provides
another damp dark home for those “critters.”

There are all kinds of products sold that claim to keep onboard water
fresh, but all that’s really necessary is an annual or in especially
warm climates, semi-annual recommissioning of the entire system—tank and
plumbing. The following recommendations conform to section 10.8 in the
A-1 192 code covering electrical, plumbing, and heating of recreational
vehicles. The solution is approved and recommended by competent health
officials. It may be used in a new system a used one that has not been
used for a period of time, or one that may have been contaminated.

Before beginning, turn off hot water heater at the breaker; do not turn
it on again until the entire recommissioning is complete.

Icemakers should be left running to allow cleaning out of the water feed
line; however the first two buckets of ice—the bucket generated during
recommissioning and the first bucketful afterward--should be discarded.

1. Prepare a chlorine solution using one gallon of water and 1/2 cup (4
oz) Clorox or Purex household bleach (5% sodium Hypochlorine solution ).
With tank empty, pour chlorine solution into tank. Use one gallon of
solution for each 5 gallons of tank capacity.

2. Complete filling of tank with fresh water. Open each faucet and drain
cock until air has been released and the entire system is filled. Do
not turn off the pump; it must remain on to keep the system pressurized
and the solution in the lines

3. Allow to stand for at least three hours, but no longer than 24 hours.

4 Drain through every faucet on the boat (and if you haven't done this
in a while, it's a good idea to remove any diffusion screens from the
faucets, because what's likely to come out will clog them). Fill the
tank again with fresh water only, drain again through every faucet on
the boat.

5. To remove excess chlorine and/or antifreeze taste or odor which might
remain, prepare a solution of one quart white vinegar to five gallons
water and allow this solution to agitate in tank for several days by
vehicle motion.

6. Drain tank again through every faucet, and flush the lines again by
fill the tank 1/4-1/2 full and again flushing with potable water.

People have expressed concern about using this method to recommission
aluminum tanks. While bleach (chlorine) IS corrosive, it’s effects are
are cumulative. So the effect of an annual or semi-annual "shock
treatment" is negligible compared to the cumulative effect of holding
chlorinated city water in the tank for years. Nevertheless, it's a good
idea to mix the total amount of bleach in a few gallons of water before
putting it into either a stainless or aluminum tank.

--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://69.20.93.241/store/customer/p...40&cat=&page=1