Air bubbles coming up downstairs toilet

22 Jan 2014
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United Kingdom
Have got air bubbles coming up in our downstairs toilet, and the toilet drains very slowly. The sink next to it is also draining slowly and can cause more bubbles in the toilet as it drains. They both drain out of the external wall separately, and then join into the same large waste pipe down into the ground outside. So they only join into the rest of the waste system under the ground.

No noises detected from the upstairs bathroom or kitchen, although I think flushing the upstairs toilet can trigger a few bubbles downstairs.

Google suggests it's either a medium blockage in the waste pipe, or blockage in the venting. If it is the venting - what is this, where is it, and is there anything I can check myself?

Any danger of the system flooding, or is it just an annoyance?
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You've got a blockage in the drain somewhere downstream of where the downstairs toilet joins the main sewer underground. Flushing the toilet or discharging any water is merely filling the pipework some more, the air that is displaced by the water is bubbling back as it is it's only means of escape.

Lift manhole covers and see if any of the chambers are full of effluent, if the drains are shared with the neighbours (or the neighbours are also having problems/have full chambers in the garden) then pass it onto your Water Company, blockages in a shared drain are now the Water Company's responsibility.
Thanks for that - what makes you think it's not a venting problem, as that's the first suggestion in most google searches? The toilet is actually draining fine now, but the bubbles are still coming, mainly when water is drained in other parts of the house (including upstairs).

I have a plumber coming for a few other things so will get him to check this. Is it worth trying some kind of drain unblocking chemical, or could that just make it worse?

And I assume that, even if downstream drains are the water company's responsibilty, they would still charge for unblocking?
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I wasn't questioning it, just wondering what it was that discounted a venting problem - I'm sure Hugh has a rational reason for his diagnosis, rather than being from the Derek Acorah School Of Plumbing. :)
A venting problem would be so much nicer to tackle than a drain full of sh*&^e, so I can't blame you for your wishful thinking. :LOL: ;)

But Huge knows what he's talking about.
You could ask yourself..

Have i changed anything in the property to make this happen?
Have i just moved into the property and just noticed it?
Have you got any inspection traps/manholes, or gullies?
Thank you Sooey, yes 25 years experience does lead me to that conclusion! :LOL:

Chemicals would probably be a waste of time, it'll be so dilute by the time it reaches where it's need it'll be useless. If you get anyone out to it though, TELL THEM if you have used anything chemical wise. That stuff takes no prisoners, and will blind if splashed into eyes! If the drain is blocked it needs rodding or jetting to clear it.

The law changed in October 2011 to bring all shared drains, and drains serving one property, from the point they pass into a neighbouring property, are now the Water Company's responsibility. This was done partly to avoid conflicts over who was paying for what when things went wrong, basically if it's your drain on your property then it's your problem. As soon as it leaves your property or someone else joins it then it's the Water Co's problem.

I suspect whilst numerous Environmental Health departments at local Council's are breathing a big sigh of relief about no longer having to get involved in drainage disputes, the Water Companies are trying to work out how much they can get away with increasing our bills by, to cover the additional costs of dealing with all these extra miles of drains! :rolleyes:
You had/have a blocked manhole, if it is running clear now then it has cleared it self. Sometimes this happens due to the pressure of water on the blockage.

A bit of bleach and hot water this morning, and no problem this evening, thanks for the help. :)

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