Repair material for fibreglass (drinking) water tank?

[Geo]

A friend is looking for some sort of solution to mending the fibre glass water tank that serves a farm and cottage

The email message I received included:- "There seems to be a hairline split in the bottom. He is concerned that some 'fillers' may be poisonous if used in water tanks. Also there is the problem of how to cover the split. I think he also mentioned that originally there were metal braces holding the tank together but these have deteriorated to some extent thus increasing the load on the shell."

Any known safe product? - I understand it has to be an internal repair since the bottom of the tank is not accessible from the outside.

Geo

[Pete C]

If the tank can be drained and dried I'd try a few layers of aluminium tape first.

If the crack is liable to 'move' I'd cover with a strip of plastic or foam before taping over it.

If worried about aluminium I'd give it a few coats of bitumen paint that is OK for potable applications.

cheers. Pete.

[Onetap]

How big is it? Domestic sized plastic tanks are cheap and this sounds like major work. If you're determined to repair it, I'd get a GRP repair kit from a chandlers, glass mat and epoxy resin. The ali tape, duct tape, sellotape or any other bodge won't work

[The Natural Philosopher]

Juts use normal fibergalss stuff, but wait a while till the pong subsides.

You will need to rough up the gel coat a bit as its probably too slick and may have release agent left stuck to it.

[Andy Dingley]

Talk to a boat chandler or real GRP specialist. You can fix potable water tanks easily enough with GRP, but the resins are specialist to the task.

[Pete C]

Hi,

If it's a hairline crack, I'd try the ali tape as I recommended, though the fibreglass inside needs to be fairly smooth. I've had good results in a similar application.

It is after all a water tank, not an offshore GRP yacht :)))

If you tie up the ballcock/valve or isolate the tank inlet then much of the remaining water can be used instead of wasted.

cheers, Pete.