Condensation on Toilet Cistern!

14 Mar 2006
Reaction score
West Glamorgan
United Kingdom
I have got a real problem with condensation on the outside (obviously :D ) of the toilet cistern in the bathroom. I do not remember ever having this problem in any of the other houses I have ever lived in.

In itself not a real problem, but it drips onto the wooden floor and is starting to cause rotten floor boards (so it must have been happening for a good few years) and I was thinking of putting down laminate soon, but it would ruin it.

I have checked that there are no leaks, and everything is fine. I checked where the water supply comes from and I always thought it was supposed to come from the cold tank in the attic? but it definietly comes straight off the rising main.

Could this be the problem?? The water being really cold because it comes straight from outside the house.

Any help is appreciated!

Is there any good ways to stop this??
Sponsored Links
I have a similar problem, though with a tiled floor it is not causing any rotting. I only experienced it when I moved to a house with no cold water tank, and so also have put it down to the temperature of the rising main water in the cistern

Condensation only appears where warm air is suddenly cooled, and without wanting to heat the water going into my toilet cistern, the only definite way I can think to reduce it is to increase ventilation in my bathroom

Ceramic cisterns may be worse than plastic cisterns for attracting condensation, is yours ceramic?

Is your boiler in the bathroom? Mine is, and I wonder if that increases the moisture content in the room.

Boxing the cistern in may help, as there will be a layer of trapped air (doesn't need to be airtight) that will not change temperature as dramatically as the rest of the room, and so will not condensate on the cistern, and the boxing in (MDF or something) will not cool to the temperature of the cistern water, so will not attract condensation itself. It will be similar effect to having double glazing, and as DannyFlash's article says that condensation only occurs on single glazing.
Sponsored Links
Same boring question time and time again, what a trial living in the modern world has become, when the mammoth problem of the day is dew drops in the bog. :rolleyes:
oilman said:
Same boring question time and time again, what a trial living in the modern world has become, when the mammoth problem of the day is dew drops in the bog. :rolleyes:

Same boring reply to the boring questions time and time again. ;)
Ye surely, if the question is sooooooooooooooooo boring, dont bother wasting your time replying too it then!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :rolleyes:
Rotten floorboards and (maybe) the joists underneath would this not be a mammouth problem???????? Perhaps not to some people!

I dont know if this would work moby_wan but could you not supply the cistern from your cold water tank in the attic instead of directly off the mains?? Just a thought!
Thank everyone :D !!!

I am having an extractor fan put in the bathroom soon, so like some of you said, hopefully the extra ventilation will solve the problem.

Thanks again for all your help! I will remember not to post such boring questions in the future lol :D
All that will do is move the problem somewhere else.

The only way is to remove the humid air with proper ventilation.
or have victorian sash windows like fitted........

draughty city !
feed it from a cistern in the loft ?

it will normally be warmer
One cause of this is cold water continully dripping internally does'nt need to be a fast drip either.

Looked at the Yank link and its correct.

But what I would recommend is foil backed bubble wrap ( This is for Insulating wall roofs and floors and wont breck up after time) stuck on to the inside of the tank which helps prevent contact of hot and cold.
Stick this on with sticks like sh*t, comes in a tube from most hardware stores.
Were are the smillys with am so cool? :D

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links