Combined waste drain system - leaking water from the top??

Question

I have this waste pipe to the back of the house which carries away the toilet waste. However, today I noticed there is small water trickle eminating from the top of the pipe (remember the actual waste pipe from the toilet is connected half way down this big pipe). I cannot seem to figure out where this leak is originating from. It can't be from the toilet waste as that pipe is connected further down. There is nothing else that is going into this pipe from the top. Could it be that the water is pushing its way up the pipe somehow and then leaking out from the top somewhere? Just doesn't make any sense?! Cheers!

Thanks for the first reply..but the pipe is outside as it is found in most old properties. You are right there is that vent at the very top (I think to allow waste smell to leave from the very top of the house). It hasn't rained today so it can't be rainwater simply trickiling down this pipe...just very odd not knowing how water can be coming from the top when there is no waste water pipe connected up there?!

It appears that I may have a partial blockage somewhere either in the soil pipe or in the manhole. Either way, I think it's going to need clearing by rodding etc...has anyone ever attempted this themsleves or would you reccomend a professional drain clearer as it could get messy!

The reply concerning steam going up the pipe might be just the answer! I've noticed that the toilet flushes just fine, there is a manhole cover near the waste pipe and there is no sign of it leaking or smells coming from it, so perhaps there is no block and it is just that in cold weather (which has just started here in the UK) could be causing this steam to rise and condense at the top. I have to say I only noticed this recently and perhaps its no coincidence that the cold weather has just started. Thanks!!

Answer 1

In cold weather, with dishwasher, washing machine, people having baths, hot showers etc the water entering the cold pipe produces steam which goes up the pipe and condenses at the top and trickles down as water.
Water is similar to electricity in that it will take the path of least resistance., therefore if the sewer was backing- up it would flow out of the toilet bowl as toilets don't have non- return valves.
Toilets on boats have non-return valves.

Answer 2

If this pipe is inside the house - then it could be a leak from the roof. as their is a vent in the top. The best thing to do is go nito the loft and see if the leak is visiable there. Try and pin point what is above the leak. It could be that the "leak" is no associated with that pipe at all, just running down it. If you have carpets in the bath room lift them to see if there is evidence of water on the floor. Whatever you do don't leave it as it could get much worse - if you have no luck finding the problem then get help.

Answer 3

You might have a partial plug in your sewer line somewhere after this vent connection. The plug would cause the sewer to back up and it's going up the vent line. Since the vent line should not normally see and liquid, it has a small leak that then shows itself. Try having your sewer rotor rooted.

Answer 4

have a professional clean your line. i rented one myself before and usually they don't come with long enough coils. it needs to be cleaned all the way out to the main sewer line. I have had good luck with Roto Rooter. Good Luck.

Answer 5

you could suck out the excess water that is trickling down the pipe

Answer 6

cold night when it warms up during the day the dampness trick ells down