Fresh water tank problem

[Randall M]

I am having a problem with gunk build up blocking my water line to the head and galley sink. Does anyone know what I can add to the water to stop this growth? The water is non potable but I dont want to damage the lines or pump.

Thanks
Randall

[S/V Illusion]

A little more info would be helpful:

What color and consistency is the “gunk”?

What are your tanks, aluminum, glass, plastic, steel?

How old is the water in it/them?

[Cyrus Safdari]

Things tend to grow when light reaches them. Clear hoses etc allow light to infiltrate into the tank too.

[Randall M]

It is green/brown , looks like algae The water was pumped out and it sat for app 3 momths. the tanks are plastic.
Thanks

[chouliha]

Time to shock your tanks with bleach. Use the search engine to look up peggie hall. We have used her advice for decades on keeping our tanks clean. We do a shock treatment about once a year or when we can get good potable water and in a marina.

[fivecapes]

Originally Posted by chouliha

Time to shock your tanks with bleach....

...only after determining it's not stainless steel.

[peghall]

Originally Posted by chouliha

Time to shock your tanks with bleach. Use the search engine to look up peggie hall. We have used her advice for decades on keeping our tanks clean. We do a shock treatment about once a year or when we can get good potable water and in a marina.

He doesn't have to search for me... Here are the directions (which are also included in both my books):


FRESH WATER MAINTENANCE (excerpt from "The NEW Get Rid of Boat Odors)
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. 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 and all bleach solution has been flushed out of it. 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…bleach does absolutely nothing to improve the flavor of good Scotch!

1. Prepare a chlorine solution using one gallon of water and 1/4 cup (2 oz) Clorox or Purex household bleach (5% sodium Hypochlorite solution ). With tank empty, pour chlorine solution into tank. Use one gallon of solution for each 5 gallons of tank capacity. (Those are the “official” directions. They work out to 1 quart or litre of bleach/50 gallons of water tank capacity , which is MUCH easier to calculate!)
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 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 vessel motion.
6. Drain tank again through every faucet, and flush the lines again by filing the tank 1/4-1/2 full and again flushing with potable water.

People have expressed concern about using this method to recommission steel or aluminum tanks. While bleach (chlorine) IS corrosive, its effects 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. And it’s that cumulative effect that makes it a VERY bad idea to add a little bleach to each fill. Not only does it damage the system, but unless you add enough to make your water taste and smell like a laundry, it’s not enough to do any good. Even if it were, any “purifying” properties in chlorine evaporate within 24 hours, leaving behind only the corrosive properties. Nevertheless, it's a good idea to mix the total amount of bleach needed for recommissioning in a few gallons of water before putting it into an empty stainless or aluminum tank.

An annual or semi-annual recommissioning according to the above directions is all that should be necessary to keep your water tasting and smelling as good as anything that comes out of any faucet on land. If you need to improve on that, install a water filter. Just remember that a filter is not a substitute for cleaning out the system, and that filters require regular inspection and cleaning or replacement.


--© 2019 by Peggie Hall

[S/V Illusion]

Originally Posted by Randall M

It is green/brown , looks like algae The water was pumped out and it sat for app 3 momths. the tanks are plastic.
Thanks

That is a pretty vivid example of what happens when tanks are left for a prolonged period after “emptied” of bulk water but not all water/moisture. There was another thread here recently about leaving tanks full vs. “empty” and this speaks to the issue some of us tried to explain about how empty tanks are not actually empty.

Assuming it’s not possible to physically clean the tank walls and pressure flush the lines, simply chlorine shocking the system is just one of those “feel good” actions which don’t solve the problem as, despite the myth perpetuated by some, chlorine doesn’t kill mold or many algae strains.

[a64pilot]

Peggie, isn’t a half gallon of bleach per 100 gls of water excessive?

[chouliha]

Originally Posted by fivecapes

...only after determining it's not stainless steel.

Our tanks are Stainless and we have been using this method for the past 3 decades with no issues or problems.

Chuck

[glcalahan]

Originally Posted by fivecapes

...only after determining it's not stainless steel.

What about bleach and a monel fresh water tank??

[a64pilot]

I go under probably the incorrect assumption that bleach does little to no harm to plastic, cause it comes in plastic containers.
May be foolish as there are different forms of plastic of course, but the day I have to replace my tanks, no question, they will be plastic, custom made, by that Mom and Pop shop in Maine that did my waste tank.

[Randall M]

Thanks to everyone for the response. I am going to go with the bleach treatment .

Thanks again

[JD-Odyssey]

Prepare a chlorine solution using one gallon of water and 1/4 cup (2 oz) Clorox or Purex household bleach (5% sodium Hypochlorite solution ).

Just beware that Clorox now adds a surfactant (detergent) to some of their bleach so read the label carefully. Make sure the Clorox or Purex you use is all bleach with no other additives.