I first noticed a wet patch on the floor around the base of the toilet on the wood floor (thought it was a mishap or two by the men of the house!). I then noticed the tiled boxing was wet and the tiles were lifting - a plumber called and could not trace the problem - think he was a cowboy, he said it was condensation!

Nikki, August 2008

Yes in some instances you get condensation on a toilet cistern (eg after shower or bath particularly in bathrooms not fitted with an extractor fan to take away steametc).
However if you have a close coupled toilet & cistern (tank sits on top of back of toilet) check between the two it could be the rubber seal gone. Or if you have a toilet with a pipe between the two parts check where the pipe goes into the back of the toilet.
To see if water is condensation or not try putting a 'blue loo' block in the cistern. Ensure you cover anything you want to protect from staining & flush the loo a few times. If the water is from a leak you will be able to trace the blue water trail back to where it is coming from.

Robin S, September 2008