Wet cold water tank!

[stevedo]

My cold water tank in the loft is very wet on the outside at the bottom, ie the platform on which it sits is wet. I thought there may be a leak, but a week ago I removed the insulation from around the outside of the tank dried everything up and on checking last night noticed that all joints to the tank are completely dry but the area underneath the tank is if anything a bit wetter.

Any ideas where this water might be coming from. I thought maybe condensation but there is no loft insulation under the tank and the loft is well ventilated. The tank is plastic, do these things develop leaks after a period of time?

Thanks for any help

 

[GasAid]

I have never heard of a plastic tank developing a leak except on the connections; afterall it's plastic. All I can think of is hole in the roof or that the c/heating is pumping over; causing hot water to poor out of the open vent; creating a bit of steam and a splash which is then soaking your board.

 

[kevnurse]

Condensation occurs on a surface when the air touching that surface cools to the point that moisture can no longer be held in that air. You appear to have the ingredients for condensation. Let me explain:

The water in the tank is very cold and if you draw a lot of water from that tank it will always be topped up with more cold water, maintaining a very cold external surface. The colder water will sink to the bottom of the tank as well. Therefore, the air touching the bottom of the tank will be cooled down and, depending on its degree of humidity, it will condense an amount of water onto the surface. If that air doesn't move away, the initial amount of water is all that it will give up. However, a slight movement of air will provide a new amount of humid air for condensation to the point that it becomes visible. All air in the UK is humid; only the degree varies.

To prove my point, if in your house you wrap your fingers around a cold pipe that appears to be dry it will feel damp, although it is not leaking. A miniscule amount of water has condensed on the cold surface, but because the air doesn't move around the pipe, the condensation doesn't increase.

I once had a normal ceramic toilet cistern, that was persistently covered in drops of water, in a warmish, but draughty, bathroom. The house was a busy place and the toilet was flushed a lot more than normal. It was only when I switched the bathroom heating off while everyone was away on holiday that I noticed the "leak" stopped.

Thats my theory anyway.

 

[holty]

you should see my mums old rubber high flush cistern, since shes had c/h put in. the condense has ruined her bathroom carpet from it.ill have to sort that one soon

 

[Softus]

I have never heard of a plastic tank developing a leak except on the connections;

I have. It happens.