Water storage tank leak

[Bill Haines]

I have this tank in the roof space. Not sure if it's plastic or fibre-glass, because it's texture in parts is very uneven, not what I imagine a moulded PVC tank would usually be like. There's an obsolete 15mm outlet that used to supply a shower unit. For some reason, maybe to maximise the pressure, the hole for this outlet is very close to the bottom edge of the tank, leaving little room for any flanged fittings that might be used to seal the hole. The current union with the tank is a male threaded fitting that's just screwed into the wall of the tank after being wrapped in PTFE tape. I could try renewing this with fresh tape but I'd prefer to make a more solid repair. Can anyone suggest an effective method? Thanks,

-- Bill Haines

[Andrew Gabriel]

It's close to the bottom, so if the tank runs empty, the hot water cuts off first so you don't get burned in the shower. Doesn't make any difference to the pressure.

Difficult. If there's really no room for a flange, then you are restricted to sealing it on the cut edge of the hole. I wonder if you can get tubeless tyre repairs that big (the conical rubber things they pull though punctures to reseal tyres)? There's a French method of fixing suspended ceiling lights which works by having a short length of very thick- walled rubber tube which you push into a close fitting hole in the ceiling, and then compress lengthwise with a screw and washers on each side so it swells and grips the hole. Something along these lines might work, with some sealant to seal around the screwholes in the washers. Make sure any sealant you use is suitable for water tanks (i.e. not a silicone sealant with fungicide).

[David Hansen]

On Sun, 27 Aug 2006 09:58:35 +0100 someone who may be Bill Haines wrote this:-

The reason is safety of people using the shower.

How little room? Is the problem that the flange would strike the bottom of the tank, or that the radius of the tank wall at the corner would prevent the flange fitting flush to the wall?

[Bookworm]

not what I

If the tank is Black it is probabably a rotationally moulded Polyethelene (or Polypropelene)Tank. If it is GRP it will probably be grey and very hard.

This leads me to believe that it is a Polyeth or Polyprop tank as you couldnt do this with GRP.

I could

I should leave well alone or replace the tank. It is a bodge that is holding. As an ex tech consultant to a tank manufacturer I have seen hundreds of such bodges. The mind boggles at some of the corners that are cut when fitting such tanks.

[Bill Haines]

A little of both I think. I got the proper fitting and cut some off one edge to compensate. Now it's sealed. Thanks to both you and A G for the revelation about the reason for the location of the outlet and other useful tips.

-- Bill Haines

[noelogara]

If its an obsolete outlet why not just drain the tank and clean the hole, let it dry and fill that threaded hole with a bung of araldite. that will stop any water coming through there. If you try to repair it you might not succeed. Incidentally putting the hole low in the tank is done to maximise the water storage. Many plumbers put the outlets well up the wall of the tank and you have a much more limited capacity than you imagine if there was a mains failure. If you had a poor main feed a decent capacity tank is vital especially if there are others drawing on it at the same time.

[Bookworm]

Do not try and try to fill the hole with Araldite if it is a black poly tank. It wont adhere.