Fresh Water Tank Cleaning

[onestepcsy37]

also good to know that, according to the epa emergency water brochure, just boiling it for one minute kills the bad stuff. think i'll stick with the combination of bleach in the water tanks and boiling it for coffee and oatmeal...

[Pelagic]

Interesting Thread…
After about 18 months of neglect while living ashore (I know stupid/stupid/stupid

We are now back to getting SG into cruising shape…. And moving back on board
Found for the first time some rust in my 1000 litre steel tank. I will open and clean out-prep…. just wondering what type of “potable paint system” anyone can recommend for steel?

[delatbabel]

Originally Posted by Pelagic

just wondering what type of “potable paint system” anyone can recommend for steel?

2 pack epoxy.

give it plenty of curing time before refilling with water but it should be fine. Check the label and the manufacturer's spec. If you have rust then I'd scrub that back first, paint over with 2 coats of something like Altex 577 (*) and then two coats of primer. The normal recommendation for topsides is to put polyurethane over that but don't bother if it's a water tank.

(*) Not an ad for Altex -- there are many similar brands of paints, low viscosity, long setting time, ideal for coating rusty or flaky surfaces because they bind through whatever coating is already there. Check the Altex specs, check the specs of your particular favourite brand, if they match then that's the stuff I'm talking about.

I'm saying this after trying 4-5 other types of potable water coatings on steel over the years, and found the simple answer of 2 pack epoxy to be the best.

[D_e_n_n_i_s]

Don Lucas & Thinwater - Does even a brief exposure to bleach cause a reaction that roughens the surface of aluminum tanks significantly to increase the growth of bacteria? Would a 2-part epoxy coating be a better surface for taste and cleanliness?

Kinda reminds me of a "speech of demonstration" I did stuffing aluminum foil into a glass bottle. I was nervous while speaking in front of the class and put way too much aluminum foil in the bottle. I figured that I would compensate by just adding a little NaOH in the form of Draino crystals, but when I tried to dump just a little into the water, nervousness prevailed and I dumped a ton out ... Mixed it up and put it into the glass coke bottle. The idea was to cap the bottle with a balloon, let it fill with hydrogen, tie it to the end of a meter stick and put the balloon over a flame ...

I covered the bottle with the balloon and it very slowly started to fill, but then as the exothermic reaction heated up, the balloon suddenly filled completely, I pulled the balloon off the bottle and felt the glass getting very hot ... with hydrogen gas coming out, of course ... My speech teacher noticed my concern and asked if we should clear out the lecture hall. I advised so, since I could just picture shards of glass exploding into the room ... She never did let me finish that speech of demonstration ...

Delatbabel - Hey, I'm for what works ... does Altex work on aluminum as well as steel? I was thinking of using a 2-part epoxy for the seems of my aluminum water tanks since I have one leaking near the top and I believe it's a seem. Using a 2-part epoxy would be less dangerous than welding because if there is a gap, I'm thinking the fiberglass under it would get hot very quickly ... Besides, 2-part epoxy is some seriously hard stuff and they make certain mixes that stay flexible. I used a gallon of Gluvit to coat my shower sole and it worked great. You just have to make sure to seal up everything before you pour out that gallon ...

I'm glad that I missed the heated debate, but I will say that of the many posts I've silently scoured, Gord May has always been courteous and most respectful and if he went off the rails in any way, it was certainly an extremely rare event. I hope that he doesn't back away from posting like usual as his feedback is continually invaluable to so very many of us. Hec, he is usually the one helping to moderate feedback that gets too heated.

Thanks to everyone contributing to this thread - I keep learning more and more - Though I may have to consult my Handbook of Chemistry and Physics for some of these scientific responses - I love it !!!

[sailorboy1]

Originally Posted by D_e_n_n_i_s

Don Lucas & Thinwater - Does even a brief exposure to bleach cause a reaction that roughens the surface of aluminum tanks significantly to increase the growth of bacteria? Would a 2-part epoxy coating be a better surface for taste and cleanliness?

In my mind the roughening of aluminum surfaces wouldn't be my main concern with adding bleach, it would be corrosion in general. Yes in theory if you have rougher surface it is easier to form a biomass on them since bacterial like to be in a bio-film and not really floating free in the water. But forming a biomass means you have a bio problem to start with. Far as a biomass issue the corrosion products that would settle out on the tank bottom would probably be more likely to house the biomass than rough walls.

So yes even a short exposure would cause corrosion, but that isn't the issue. Corroding the tanks are!

So if I had alum tanks (and I did an my last boat) and I had concern that the tanks are really fouled I would be looking to: 1- physically clean them 2- do a peroxide add to get to 2-5% in the tanks for an hour (amount depends on what concentration of peroxide you can get), 3-drain and flush, 4 - fill with clean water.

if I didn't have the peroxide I would maybe consider vinegar, or go ahead and use the bleach understanding that the tanks would need to be well flushed afterward (I personally would use the bleach)

Someone asked about the safe drinking concentration for peroxide in the tanks. Far as I know there is not an established level of peroxide concentration that is considered safe/dangerous for drinking. I know when I looked for this a few years ago to do my tanks I could not find it. I think the "fuzzy" taste would be an issue before a health one.

[Pelagic]

Thanks delatbable... I can get Altex here in Subic

[D_e_n_n_i_s]

Aha, the evils of corrosion - Yep, that would be the killer ... I completely agree about the physical scraping and cleaning that will be needed. I'm going to have inspection ports cut into the top of both tanks and will need to cut something similar into the baffling to get to both sides of each tank. I had inspection ports cut into my diesel fuel tanks to clean them out and what a mess they were too, but great to have access into them ...

I think I'll do an initial scrub down with bleach and then use vinegar for ongoing treatments as needed to keep down carbonate build-up and clean things up. I'll not only run the water coming into the tanks through UV-lights, but will look at also buying the UV-lights that can drop down into the tank itself. I think UV light is ultimately a better option than bleach or vinegar - Use solar cells to charge up batteries, use a little electricity for the D/C UV lights and you have a renewable energy sterilization process ...

[sailorboy1]

Talk about overkill!!! Maybe this should be moved to the joke thread.

[D_e_n_n_i_s]

It does sound a bit extreme put like that, but some of it is unavoidable. I have to scrub out the tanks to get rid of the carbonate build-up over the past couple of decades. An initial bleach treatment makes sense. I haven't purchased any of the UV lights yet (still researching D/C units for treating water as it is collected and units that sit in the tank for periodic use) so I may have to use vinegar treatments until I'm fully set up. I guess just listing it all together that way does make it sound like I'm a germaphobe, which I'm not. Hmmmm, better set the story straight before folks start calling me "MonK" lol ... Well, I do want my drinking water to be safe

[scoundrel]

I have read before that way back when, sailors would put a few silver coins in the barrels of the drinking water to prevent algae from growing. I know silver is used in the medical field for the for its antibacterial properties. just wondering if anybody has tried this.

[sailing_jack]

have you ever used a Sterasil (sp?) water filter. It uses silver as the biocide. I dont know how you would use silver to decomtaminate a tank, but using these kinds of filters will give you safe drining water

[sailorboy1]

lets see:

bleach/peroxide = $
silver = $$$$$$

PS - I wouldn't drink any water that can dissolve enough silver from a silver coin to kill stuff in a water tank. But that's just me and I ain't no expert !

[sailing_jack]

I can't imagine that a lot of silver is needed. A single tap filter cartridge lasts a year and only costs ~ $30

I think the ceramic part is 5 micron, then there is charcoal, and then silver.
We use it for drinking water at our cottage where we take water from the lake.

[gts1544]

Killing Power Of Bleach Increased By Vinegar

Adding white vinegar to diluted household bleach greatly increases the disinfecting power of the solution, making it strong enough to kill even bacterial spores.

A convenient formula to produce a solution of acidified bleach is 1.0 cup (8.0 oz.) of concentrated bleach (approx. 5.25% NaOCl) added to 1.0 gallon (128 oz.) of tap water, and then add 1.0 cup of 5 % distilled white cooking vinegar. Follow the warning directions on the bleach label. Do not add cleaning solutions containing ammonia to bleach. After an exposure of 20.0 or 30.0 min, rinse the surfaces to remove the bleach. Use acidified bleach within about 8.0 hrs, and then discard to a sanitary drain.
➥ Biodefense work by MicroChem Laboratory[/QUOTE]

Folks, For years my wife and I had been keeping a gallon jug of water with 1 cup of bleach added under the sink for disinfecting purposes in our kitchen (counters, etc.). Then someone I trusted told me that it would be much more effective if I would add a 1 cup of vinegar to the solution, which I did, very carefully (1 cup of vinegar, add 1/2 gallon of water, then 1 cup of Clorox, fill with water)! I now use the same solution to sanitize my tanks aboard, though not in the same concentrations. Gordon, I am glad to see something in writing that verifies what I was told. Your contributions to these forums are invaluable. By the way, I grew up in Duluth, not too far from you. George

[thinwater]

^^ True enough. And a clear indication of why often less is more with sanitizing with bleach. If the users follow ANSI procedure, using the correct amound of bleach, the high pH situation does not occur. More is not better.

This one I need help with, feeling too lazy to do the research: if we mix vinegar with bleach, do we make haloacetic acids, and how efficient is the conversion under the stated conditions? The primary standard for these is 60 ppb (carcinogen), so I would say that we do NOT EVER want to add vinegar to bleach as a primary or secondary disinfection practice (other than annual sanitizing) and that we must be certain to rinse very well. Normally TOC is limitied to 2-4 ppm before disinfection to reduce DBP formation.

I know you were not suggesting this as for primary or secondary disinfection practice, but I thought it bore emphisis.