How can I Patch a Hole in Cold Water Storage Tank lid? All aspects of plumbing questions and answers, help, tips and information

[Diy3r]

Hello!

Looking for some advice please. Just noticed that my cw tank in the loft has quite a big hole in the lid. What looks like has happened is a hole was made for the vent pipe from the hot water cylinder, and for whatever reason the hole was in slightly the wrong place, so a second hole has been made, which is where the vent now sits. The two holes over lap to some degree, so it looks a bit like a figure of 8 which the two holes side by side, overlapping a little.

I am wondering what a safe way to cover the unused hole would be? I am a little concerned about moisture / steam escaping into the loft from this hole, and also the potential for vermin to get into the tank. The tank does have an insulation jacket across the top. I appreciate this water is not drinking water, however as its used to feed the hot water cylinder, bath in, brush teeth etc, I don't want to use anything 'toxic' or dangerous or something that might get mouldy (wood etc), equally I want something quite sturdy to patch the hole (to keep vermin out and moisture in). I measured the dimensions of the lid and I cannot get a new lid through the loft hatch, hence the patch. I notice the underside of the lid has lots of water droplets, not sure if that's from steam from the vent or just a natural thing when you have a lid over a large amount of water (hence my moisture concern).

Is there a particular plastic I can buy, or a water-safe tape etc I use to patch the hole please?

Any advice gratefully welcomed!

[proptech]

Hi Diy3r

I wouldn't worry too much, the water on the under side is quite normal, and will always be there.
As far as the oversize hole is concerned, OK, it should be sealed, but the simplest thing that comes to mind is duct tape.

[Diy3r]

Thanks for the reply / advice proptech - much simpler than I thought, for some reason I had in my head that duct tape might get mouldy from the moisture. Shows what I know!! Thanks again

[Diy3r]

Just an idea - would does anyone have an opinion on whether I would be able to cover the hole with plastic, just wondering if indeed under the humid / damp conditions of the underside of the tank lid that duct tape, or any tape for that matter might end up getting moldy.

[proptech]

I could think of all sorts of things. Go to the pound shop and get some plastic object that could be cut down, and the rest discarded. Cut to the shape required, and drill a 22mm hole for the pipe. Fix in position on the underside, and secure with 4mm brass screws and nuts.
Or just use a bit of duct tape !