Dripping External Overflow Pipe

5 Jul 2012
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United Kingdom
Hi all. This is my first post so go easy on me. I've tried searching other posts for answers but nothing really seems to fit.

I have two external overflow pipes. One at low level and one higher up. i'm assuming these are related to my upstairs and downstairs toilets. A while ago the lower pipe started dripping. It turned out that the downstairs toilet was overfilling after flushing and I have since remedied this.

In the last couple of days the higher of the two overflow pipes has started dripping outside. I assumed this would be down to the upstairs toiled overflowing. Having checked though, the water level in the upstairs toilet is no where near the overflow pipe. I'm now at a loss as to where this dripping is coming from.

I have a condensing boiler on the first floor of the house and the condensing pipe rises to the loft and out into the soil stack. I'm not sure if this is causing the drip or if it could possibly be anything else?

I'm very much a diy novice so any help or advise would be much appreciated!

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Is the over flow from the upstairs toilet run internally before it exits?

Did you check the upstairs toilet cistern?
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Sorry should have read your post better.

Have you checked the cistern while it's dripping, as the valve may be letting by intermittently, or have a slow drip so that it overflows if not flushed for a a day or two and then looks normsl
It's a white plastic pipe to outside the front of the house. I'll take a closer look at the cistern upstairs later but just wondered if there were any other possible sources?
Sometimes on a combi, they leave some of the cold water on tank, but If your defo sure you havnt, would put my money on the toilet
Ok so I've checked the cistern again in the upstairs loo. After flushing there is a very slow drip but the water level is a good 3cm below the overflow pipe. The toilet rarely goes more than 12 hours without flushing and I just can't see that drip filling it to the point where it does overflow. I could of course be wrong!

Daft suggestion but is the overflow connected to the guttering in any way?
How about you fill your upstairs cistern up with water till it goes down the overflow and see if water comes out the same external pipe.
If it does, then your toilet (float valve) is at fault. If not, the problem is elsewhere.
Check to see if the pressure is dropping on the boiler pressure guage.
Thanks for the ideas. I've checked the pressure on the boiler. It doesn't seen to be dropping but I will monitor it over the next few days to be sure. The boiler is only 15months old so I will be extremely annoyed if the problem originates from there....
Did you try pushing the ball valve down in the toilet to make it over flo and then checking the pipe out side as suggested above.

That's a pretty good idea for eliminating it

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