Water Tank Leaks

[Rogue Brit]

Does anybody know how to repair, in place, plastic (polyethylene?) water tanks? My leaking water tank is located in a virtually inaccessible place, and could never be removed without dismantling the boat.

I tried heating, and fusing together one spot, it changed the look, but it still leaks, and I suspect there may be more leaks where I can't see. Is there some magic goo that one could smear on? or perhaps a fiberglass layer would adhere to the plastic.

The boat is a Hunter 466, and the leaks are in tank 5 which is below the floor under the aft bathroom.

Desperately need advice … Trev

[wingssail]

Put a bladder in it

[Lepke]

I use a plastic welding tool - Bondic. About $30 on Amazon.
If it's a stress crack, I drill both ends (to relieve stress) and grind or scrape out the crack to make a larger bonding surface and apply the filler. The pen has a UV light that cures the filler in a few seconds. Afterwards you can sand or file the filler if necessary.
If neatness doesn't count, you can skip the grinding and just do a buildup on the surface.


There is a plastic welding process like gas welding, but it takes a skill that can't be quickly learned.

[CassidyNZ]

Most plastic tanks I’ve come across will not have anything sticking to it. I use similar plastic in mixing bowls for epoxy and it never sticks. Nothing sticks. Not epoxy, not PVC glue, not hot glue, not contact adhesive, nothing.

Needs to be welded.

If the tank can’t come out and you have more than one leak, you have a lot of frustration in your immediate destiny. If you can cut a biggish hole in the top, I reckon wingssail is onto it, squash a bladder into it. Then your only problem is connecting your plumbing to the bladder.