Constant blocked toilet

[craigap]

We live in a relatively new build (<10yr) house and the downstairs toilet appears to be blocked most of the time. Once the toilet is flushed it can take anything from 10seconds to a couple of minutes for it to empty away from the bowl, often leaving remnants in the bowl due to not having a 'flow'. The toilet and sink are the only things on this soil pipe, which goes straight put the front of the house.
Not sure if the following has anything to do with it or is just a red herring but the sink is plumbed in to the toilet just after the U bend. When I tried a toilet plunger some water shot back up in to the sink.
Also in the unit behind the toilet where the main stop cock is, there is a section of upright pipe with a cap pushed on it. When I remove this can the toilet clears freely and very quickly. As soon as I put it back on, we are back to the same issue again. Is this all correct and the problem lies further down the pipe?

 

[Elsa TLC]

Check in loft to see if it's been vented correctly

 

[Mottie]

Also in the unit behind the toilet where the main stop cock is, there is a section of upright pipe with a cap pushed on it. When I remove this can the toilet clears freely and very quickly.

I assume you mean cap? If so, does that contain a one-way valve that lets air in but keeps smells out? Check to see if the valve is working.

 

[craigap]

Check in loft to see if it's been vented correctly

It's ground floor and goes straight outside, so doesn't go via the loft.

 

[craigap]

I assume you mean cap? If so, does that contain a one-way valve that lets air in but keeps smells out? Check to see if the valve is working.

It's a Polyvent cap which does appear to have a valve that should lift up but when monitoring it whilst flushing, it doesn't seem to move or do anything.

 

[Mottie]

It's a Polyvent cap which does appear to have a valve that should lift up but when monitoring it whilst flushing, it doesn't seem to move or do anything.

Well if everything is okay with it removed, it could suggest that it is faulty.

 

[Wayners]

Cap?

air admittance valve required or do you have one and it's faulty?

 

[freddiemercurystwin]

It's a Polyvent cap which does appear to have a valve that should lift up but when monitoring it whilst flushing, it doesn't seem to move or do anything.

Do you have access to it? Has it always been like this? Have you lifted any manholes etc to see what's what?

 

[Nige F]

AS above - lift a manhole cover - chances are it'll be ful

 

[Mottie]

No pictures though - not at tea time…….

 

[Jurassicspark]

Lol

 

[oldbuffer]

It is likely that the cap is for an air admittance valve (AAV). When the valve detects a slight vacuum (such as when water goes down a pipe) it opens to let air in. When the vacuum is gone, the valve closes again, stopping any smells getting in. If it is an AAV then:
1. It is possible the AAV is faulty. If so, replace it.
2. If it is enclosed within boxing in, that boxing in must not be fully sealed but have some air entry. If sealed, provide some ventilation.

 

[craigap]

Well, I found a covered over man hole and lets just say it was brimming! Somehow it seems that tissue built up at the bottom where it goes into the neighbours drain. Took some hard (and smelly) work to sort it but managed to clear it all away and the toilet seems to be working as expected now.
My only concern is that it will build up again in time as the run off to the other drain seems very slow and even leave about a 10mm water puddle in the bottom so assume the gradient isn't what it should be. Also, the pipe leading to the other manhole is a smaller diameter than what's coming from the toilet. Either way at least I know what to look out for now as soon as I have any further issues.

 

[freddiemercurystwin]

Tissues? Bog roll? The dreaded wet wipes? Cotton wool pads? From your house or upstream?

 

[craigap]

Tissues? Bog roll? The dreaded wet wipes? Cotton wool pads? From your house or upstream?

Toilet roll, no wet wipes and the adjoining drain didn't seem to back in to ours, so just must have built up over time once the initial part blockage had started. It took some work to it all so must have been months. Drain rods and lots of hot water!