Using Holding tank as a water Tank?

[squarpeg]

So we have been considering switching to a composting head. That would leave our holding tank empty. This tank is built into the boat under a bunk. It is fiberglass. It also does not have great access to cleaning as there is a single "port" in it. Probably 40-50 gallons. I'd love to use it for fresh water but thinking if that would ever be possible? What do others think?

[Allied39]

I think it'll be fine, whats the worst that could happen......get the man made bat virus?

[rslifkin]

Unless you have good enough access to scrub the inside thoroughly and make sure it's spotlessly clean before shocking it with a strong bleach solution, I wouldn't even consider it. If you can't get it completely clean inside, it doesn't matter what you do, you'll never get it sanitary. Plus, the tank isn't necessarily made with drinking water safe resin or gelcoat, so you'd probably want to coat the inside after cleaning anyway.



That said, if it's a fiberglass tank, you can probably cut the top off it, clean, coat, etc. as needed and then rebuild the top.

[squarpeg]

Originally Posted by rslifkin

Unless you have good enough access to scrub the inside thoroughly and make sure it's spotlessly clean before shocking it with a strong bleach solution, I wouldn't even consider it. If you can't get it completely clean inside, it doesn't matter what you do, you'll never get it sanitary. Plus, the tank isn't necessarily made with drinking water safe resin or gelcoat, so you'd probably want to coat the inside after cleaning anyway.



That said, if it's a fiberglass tank, you can probably cut the top off it, clean, coat, etc. as needed and then rebuild the top.

I had considered taking a sawzall to the top to get better access.

[Jim Cate]

Could cut off the top, clean well and then use a bladder inside the topless tank. Safe and reasonably easy to accomplish.

Jim

PS There could be a lingering smell associated...

[rosatte]

Hell dogs drink outta toilets what’s the big deal

[ilanortho]

Pull tank out and insert new tank. Even if I could scrub my toilet till it gleamed I would never drink out of it. Is why we use autoclaves for surgical instruments or ultrasonic chemical sterilizer baths (heated).
Don't think I could ever wrap my head around drinking out of such a tank. Don't think Peggy Hall would add such a chapter to her book either!

[boatpoker]

Unfortunately Sharon and I won't be able to make it for tea next week.

[GB32]

Originally Posted by boatpoker

Unfortunately Sharon and I won't be able to make it for tea next week.

:

[Kiwi.]

Originally Posted by Jim Cate

Could cut off the top, clean well and then use a bladder inside the topless tank. Safe and reasonably easy to accomplish.

Jim

PS There could be a lingering smell associated...

The best advice. I owned a water treatment company for a number of years, it didn't make me much money, but I learnt a lot. It's extremely easy to sterilise the inside of a tank with bleach (you're not doing open heart surgery here, and nobody puts their cutlery in an autoclave!). But if the finish in the tank isn't potable water standard than you can slowly poison yourself. A very experianced solo circumnavigator I know painted the inside of his holding tank with leftover antifouling! So a potable water bladder shoved inside after cutting out a manhole is a great idea. Bleach the tank and scrub it to stop smells but unless you can get a full specification on the tank coating I'd use a bladder.
Bladders are actually great in any tank. The breather stays connected to the tank not the bladder so there is no outside polution entering your fluid. Modern plastic bladders can only be killed by sunshine (UV) and there's not a lot of that inside a tank, so they last extremely well.

[gonesail]

you can never get a built in tank like that clean .. even if you cut the top off. the insides are rough not gel coat. not worth it

[Fore and Aft]

That new water tank might even start a new strain of boatvid. Similar to Covid except for the shortness of breath or coughing is caused by receiving a boatyard bill or marina bill. Death might even happen if the wife receives the bill first.
Cheers

[jen1722terry]

Hi, and congrats on your new composter. We love ours, but you will miss the incomparable joy of cleaning out head clogs.

We've written on composters and holding tanks several times over the years.

So, again, you may want to consider plumbing the liquids tank of your composter to your holding tank. Why?

1. The liquids tank can fill up quickly when you're sleeping on board or have guests.

2. It may not always be legal to dump your liquids overboard.

3. At the very least, it may be rude to dump your liquids near other boats.

4. If you're just using the holding tank for liquids, pumpouts are infrequent, particularly if your tank is in the 40-50 gallon range. Our tank is only 18 gallons and we pumpout every 2-3 weeks. We're full-time live aboards all summer.

5. You minimize the risk of liquids seepage or spillage when you forget to emtpy the small liquids tank. Also, we can attest that folks sometimes drop their liquids tank when emptying it either in the cabin (spillage) or overboard in rough weather (TOB emergency), unfortunate in either case.

6. You'll enjoy your composter even more with this setup.

Just some thoughts. PM us should you like more info on our 9 years of composter experience.

Cheers

[Kd9truck]

I would not use the tank for anything as designed except fuel, reguardless of the cleaning process, and there would still be work to get that space right to hold fuel. I have seen large volume bladders in many sizes for water, I do not have a link to share unfortunately, but it should not take long to find it on line. They make them in V shapes for say under the bow birth or in sizes to fit in the soul between bilge bays.
Usually if you need water storage you need fuel storage, have you though about making it a back up to your fuel tank? You would still have a good deal of work to make that happen,…. butt it’s better than thoughts of gost odors, or your crew $#!+ talking your water quality, or needing an extensive arsenal of dysentery meds.

Cheers

[KenKo]

I don't know if this is a plausible solution given the plumbing system on your boat, but could you isolate the plumbing from the tank so it only supplies a shower and/or boat washdown system and also possibly the freshwater toilet flush on your boat and not the drinking water? Just an idea--I never tried it myself or encountered a situation where I needed to.