clean water tanks

[Regal2800]

what is the best way to clean my fresh water system? The other day i noticed that some of the clear water hoses were darker in color. i removed the hose and icould see how dirty the lines were. Now i can't see inside my water tanks but i would assume they are just as dirty. what do you guys do to clean out the fresh water system? worse case hoses can be changed out, but does everyone do with the tanks themselves? Chlorine etc is a good idea but it will only kill bacteria and i dont think it would do much to actually clean the tank. Any ideas?

btw how much chlorine is safe to add to 190 gallons of tank water which is used for drinking?

 

[MikeP]

I have never cleaned the tanks in the sense of removing the built up materials. But I'm sure the same cleaners that remove it in home systems would do the job. Frankly, I wouldn't worry about it at all - we don't worry about cleaning our home plumbing systems. But vinegar would do the job safely though you'd need a lot of it!

I only use tank water on the boat so it get's turned over quite rapidly. And I make sure the tank is empty before leaving the boat unattended. Of course, "empty" leaves a bit of water standing in the tank.

I use clorox in the tank every year when dewinterizing. I pour 16 oz of clorox in the 287 gal tank (actually two tanks, one filler) before filling. This is a lot of clorox, more than is actually recommended for water purification which is 1/4 teaspoon per gallon of water taken from a surface water source. I figure that water sitting in the tank for some months qualifies as a surface water source. When taking a shower I can smell the chlorine. I run that tank of water through the boat as normal. From that point on I do not add any clorox. The calculated correct amount of chlorine for the tanks would be 12 0z for 287 gal tank, treated as surface water. For water out of a tap, it would be half that - 1/8 teaspoon per gal.

I have been told by a good friend who is also a doc that my chlorine dose is a bit strong and that burning eyes in the shower from the chlorine fumes might be overdoing it a bit...but I'm clean!

But we have never had the slightest ill effect from tank water on our boat in the 7 years we have owned it so why mess with success?

But again, the recommended dose for treating water with clorox is 1/8 tsp per gallon for water from a tap and 1/4 tsp per gallon for standing surface water.

 

[bobk]

My favorite subject since I spent nearly ten years studying the effect of water disinfectants on plastics and rubber following the failure of the polybutylene plumbing system in this country.

First a word of caution. More chlorine is not better. Chlorine is toxic, and it also destroys some kinds of plastic and rubber. Ten PPM (parts per million) in a horses drinking water is reported to be fatal. Chlorine also reacts with algea or other organic detrius in surface water to produce THM's (trihalo methanes) which are carcinogenic. As a result of the later, public water companies rarely use straight chlorine for disinfecting surface water. Rather they use chloramines produced insitu by adding ammonia first to prefiltered water, then followed by chlorine.

How much is safe? Depends on what you are trying to do and on what form of chlorine you are using. One tenth of one part per million (0.1.ppm) residual chlorine is usually enough to kill bacteria and keep them away. For municipal, treated poteable water that should be enough. If for some reason you are using an untreated source, you might go to one or two ppm. You start to smell it in a shower at 2-3 pph depending on the pH of the water.

You should be able to shock your system with 10ppm chlorine. That's what the city of Miami, FL used to do to clean their pipes before the snow birds arrive in the fall. Fill the tank 2/3 full and try to run in a big seaway. Then drain and rinse thoroughly. And hope you didn't shorten the life of your rubber components too much. When calculating how much to add, figure household bleach contains about 2.5% active chlorine.

Personally, I like to add a bunch of NaHCO3 (bicarbonate of soda) to the system and let it sit a day or two. That seems to sweeten the tank nicely. Just don't get it in your eyes until you haved purged well.

All that said, I suspect you will not see the vinyl hose look much cleaner, but the water should taste and smell better. Like Mike, I try to use the tank water unless Gayle is washing lots of clothes.

Bob Kassal
Chateau de Mer
1981 48MY

 

[daniel r morrison]

does anyone know if the city, county or local univeresity can assist you in a spot check on the quality of your water if you brought them a sample. I heard somewhere they do this for private wells. maybe the service is available for free

 

[MikeP]

I hadn't thought about the baking soda as an additional treatment - sounds like a good idea.

I'll recalculate the amount of clorox I use and do as you (and Dr Jim) suggested, using somewhat less than my "eyes-burning in the shower" amount.

 

[bobk]

does anyone know if the city, county or local univeresity can assist you in a spot check on the quality of your water if you brought them a sample. I heard somewhere they do this for private wells. maybe the service is available for free

What do you mean by water quality? If you are thinking about residual chlorine, that test has to be done in the field as the amount is not stable.

We used to send water samples to one of the Wilmington, DE water purveyors for detailed analysis.... but that is not cheap. The practice of any municipal or state agency is likely to be a function of local law.

Bobk

 

[Regal2800]

This is good advice thank you.

Now 1/8 tbsp per gallon is with chlorox or chlorine? the two were chemicals were both used and im not sure what the difference is? Chlorox is bleach so i assume it does the same thing but i am not sure.

WM sells a bunch of different water treatments but i think they are basically selling chlorox or bleach and charging $20 a gallon

 

[MikeP]

Go here - about 2/3 down the page for specific recommendations from the Washington State dept of health.

http://www.doh.wa.gov/phepr/handbook/purify.htm

 

[Hat52MY]

Below is an article put together by Texas A&M that discusses Shock Chlorination of Stored Water Supplies. My one variance is instead of using bleach (horrible after taste IMO) or liquid chlorine (issues w/storage onboard) is using Sodium Dichlor. You can get Sodium Dichlor at any good pool supply store (typical use in fiberglass Spas), its granular and easier to store. One 1lb (16oz) bottle (resealable) will treat 10,000 gallons of water. Best of all there is no chlorine or bleach after taste to the water. I get a gallon water jug and mix in the appropriate amount of Sodium Dichlor and while I am filling the tank will add in the gallon mixture. Let it set for 12 hours and its all good to go.

http://soiltesting.tamu.edu/publications/E-351.pdf

On a side note, I watched them use Sodium Dichlor to treat a pool on a foreclosed house. The pool looked more like a pond, even with fogs & tad poles. They removed as much of the physical debre as possible, water was still green. They dumped in several pounds of Sodium Dichlor, turned the pump on and in about four days the water was sparkeling clear.

 

[Passages]

Probably more than you ever wanted to know about the subject.

http://www.samsmarine.com/forums/showthread.php?33-Fresh-Water-Tank-maintenance&highlight=quaternary

 

[bobk]

IMHO there are some technical errors and bad advice in the items from Washington State and my Aggie friends.

Household chlorine bleach is typically 5.7% NaOCl, which is about 2.5% Cl (atomic weights Na - 23, O - 16, Cl 35.5).

Only small MUD's use the hypochlorite method. Most, if using a chlorine based disinfectant, use Chlorine, Cl2, which is a gas at RTP. I sure hope the average individual can't buy it for personal use.

200 PPM? WOW! Never on my boat. Maybe that is why I'm at 5.5 years on my Sureflo pump w/o problems. Anyway, to each his own. I always hesitate to post on this issue because there are so many experts around who will disagree.

Cheers from the healthy, happy crew of
Chateau de Mer
1981 48MY