Mould on Loft water tanks

by **bluenun** » Tue Nov 11, 2008 9:50 am

When I moved into my home last year the big water tank anf the little water tank which I think is called the header tank both had black plastic insulation tied around the sides bit it had fallen in the tanks.

Whoever had done work up there had left it in a mess and htere was some straw from a birdnest in the tank too.

I took out as much rubbish as I could and them made 2 plywood covers which I undercoated and glossed and fitted them over the 2 tanks.

It has been a few months since I did that, today I looked up there and the bottom of the glossed wood had condensation on and had a small amout of black mould on it which I assume could drip into the tanks.

Is this dangerous in any way?
I do not drink tap water but I do use it when brushing my teeth.

by **nitro23456** » Wed Nov 12, 2008 10:30 am

buy a proper plastic lid from screw fix. you are always going to get atleast some condesation from there. The small tank is central heating F&E tank so if its this one (which is the more likely to have condesation) I wouldnt worry too much.

The insulation is to prevent the water from freezing and bursting pipes in the winter, so replace it dont discard it.

by **bluenun** » Thu Nov 13, 2008 12:51 pm

Thanks for the reply.

I did not know plastic lids for tanks were sold so I will take a look on screwfix and see if I can find them.

I have lagged all the pipework in the loft.

What do you mean by "F&E" tank?

Both tanks had condensation, it is the big tank I am concerned about as I think that is where the drinking water comes from and I expect some mould will drip inot the tank.

by **nitro23456** » Thu Nov 13, 2008 5:49 pm

im sure screwfix used to sell the lids separatley but i cant find them online now! Im sure you can pick one up at B&Q or wickes.

F&E = feed & expansion

The tanks themselves still need to be insulated to prevent the water freezing.

by **bluenun** » Sat Nov 15, 2008 1:25 pm

B&Q do sell water tank lids but I measured my tank and the sides are not straight, they are bowed so the width at either end is 59cm and in the middle 70cm.

So the lid B&Q sell does not fit.
Wickes only had 4 and 25 gallon tanks and lids.

Plumb Centre had lids but were straight again.

I managed to find out mine is a 50 gallon tank "Osmaflow PC50 50.KC.227G"

I have searched online but cannot find anyone that stockes this.
Do you or anyone else have any idea where I can get one of these?

If not I will have to put the wood cover back on or cover the tank with some sort or breathable membrane which should stop mould growing.

by **nitro23456** » Sat Nov 15, 2008 7:22 pm

I dont like the sound of a bowed tank and I would question its integrity.......... I'm sure its probably fine, but it certainly wasnt originally designed to bowed.

Whats your homemade lid made of? How about a new one - unpainted marine grade plywood.

Personally, longterm I would be looking at replacing a bowing tank and you would be able to get a perfectly matching lid.

Someone else may be of more help.

by **bluenun** » Mon Nov 17, 2008 4:06 pm

It was made with bowed sides, that is the design of the Osmaflow tank.
I telephoned the company that supplied it, they were very helpful but they stopped supplying these back in the 1980's so I wont be able to get a lid for that one.

The lid I made is made from MDF and sawn batten, undercoated and glossed twice.It fits very well but condensation forms on the underside of the lid and this is where black mould is starting to form.

Marine ply is a good suggestion.