Forums, Internal Fixtures and Fittings, Keel water tank, off-taste...?

Tazling at 15/07/2013 02:08:37
Love my CO32 but her integral water tank (in-keel, below the cabin sole) seems to impart a funny taste to the water — not really potable, even with a filter inline. It is crystal clear, just tastes strange.

Inspecting I see a couple of things: there’s stuff growing on the tank walls; the gelcoat is cracked in many places; and the inspection port lid (a 6.5 inch diam threaded plastic dealie in about an 8 inch dia plastic flange) is not watertight - when I overfill the tank, water comes seeping out around the allegedly secured port. I also see that there’s a baffle between the fore and aft portions of the tank, making it (ahem) “challenging” to clean more than a tiny portion of it.

Other than dumping some bleach in and living with chlorine taste in addition to strange off taste :) does anyone have suggestions for cleaning out a tired old integral water tank?

cheers

de

admin at 15/07/2013 10:57:11
If the tank is GRP there is a reasonable chance if has osmotic blistering and this will make the water taste “off"; even after a short period of storage, no amount of cleaning will fix this, trust me I tried and tried again. The only option was to replace the tank with a new one in stainless steel. Clean and fresh water ever since now, even if stored for some time. I think some people have lined their existing tank but I’m not sure of the cost of ease of doing this. Sorry this is probably not the answer you are after.

James Chew at 15/07/2013 18:15:13
Is there anything to be said for steam cleaning it to kill the living stuff?

Tazling at 16/07/2013 06:53:35
Hmmm, “replace”? as far as I can tell the tank is a void in the keel; I’m not sure how it could be replaced — my impression is that outside the tank walls it’s all ballast. Could be wrong about that though! at any rate it spans quite a section of the cabin sole, major boat surgery to get at it… I was thinking maybe a pressure wash. In the meantime I’m carrying drinking water in bottles, and using the tank water for washing-up (of dishes and persons). This will get me through local summer cruising all right.

I’m trying to come up with a description of the off taste and all I can say is it is as if there were a bit of bicarb of soda mixed in. Not very palatable! Is that typical of osmosis?

George Isted at 16/07/2013 09:36:21
Unfortunately, changing the tank is a significant undertaking, the floor has to some up and then the tank removed where it is bonded into the gap between the hull sides just above the lead ballast. I’ll email you a couple of pics but also see the technical section of the website that has a paper on replacing the tank and floor. Just a thought but have you tried a shock-treatment of the tank and it’s pipework with chlorine bleach, you can later neutralise of most of the chlorine taste with a vinegar solution. As well as a clean tank have you checking/replacing the pipes as they can also contain lots of nasties. Does the inside of the tank have any blisters or pimples as this is a sure sign of osmosis and is quite common on the old water tanks.

nardus at 16/07/2013 09:46:28
Same problem here, no need to replace the tank with a rvs one. The rond hatch gives good acces for someone with a long arms. Dry out the tank a few weeks , sand down the blisters and give it few coats of special food grade epoxy. Very important to mix the epoxy thoroughly using a double pot method discribed in :
http://www.epoxyworks.com/18/pdf/tanks.pdf