Toilet trouble

hampshirebabe

I've had trouble with my toilet for a few weeks now, but I can't work out the problem, or how to fix it. I'm in a downstairs flat, one flat above, but her toilet waste pipe is separate. The toilet starts draining slowly, like there's a blockage, but then sucks the water out to leave the toilet empty, gradually the blockage get worse till it won't drain at all. A plunger, (even a super-duper one that people say clears anything) makes it a bit better, but won't cure it. Then eventually there is a big noise and the water suddenly gushes away and everything seems to be working fine. But then it all stars again, slowly becoming blocked and getting worse. It's happened 3 times now.
What's causing it to get slowly blocked so frequently, and how can I solve it? 

Jeepers_Creepers

Hmm, almost certainly a blockage as you suspect.

What causes the strange behaviour is that (I'm guessing) something like the soil pipe up to the blockage point, or possibly in the inspection manhole, is backing-up (filling up) with your toilet water until it reaches a pressure point where it blows away the blockage, at least to some degree. The built-up column of water - which is completely filling the soil pipe like a piston in a cylinder - then gushes away much faster than it would normally and 'sucks' a column of air down behind it - this is what empties your bowl's U-bend.  In theory, your soil vent pipe - which continues up to roof level - should allow air in to prevent this from happening, but I guess it cannot cope.

Basic things to check - can you see the top of your vent pipe outside the house? Anything - a nest - blocking it? Are you sure there is a vent pipe, or could you possibly have an air-admittance valve instead? 

Finally - the horror - you need to lift the manhole cover...

It does appear that there is a blockage, and this is simply not fully cleared each time. It could be something like tree roots which create a 'web' inside the soil pipe, and this catches passing, er, stuff now and then; it stops its passage, it builds up, it breaks free, and then another thingie comes along.

Homer_home

Does your neighbour have kids by any chance?

Apodemus

Since it sometimes sucks all the water out, you might want to check that the vent pipe (could be external or an internal valve) is functioning properly.  Potentially that could lead to the soil pipe filling with water until there is sufficient weight for it all to overcome the suction, giving rise to the slow flow followed by sudden complete draining.

FreeBear

Flat - Leasehold or rented ?

If rented, write to the landlord at the address given on your tenancy agreement.

For a leasehold property, contact the leaseholder (or management company) and get them to sort out the drains - Again, do it it writing.

hampshirebabe

Thank you for your help so far, from what I've read I think it is a problem with the vent pipe, but I'm not sure where it is. These are the external pipes, there's a small plastic pipe just behind the toilet, or there are several covered ventilation pipes, I'm guessing it's the top one, but nit sure how to get up to it. I've read running a hose pipe into it can clear the blockage quickly, but if I'm nit sure it's the right vent pipe that sounds risky. These are the 2 bathroom windows, the toilet is to the left of the window, and the boiler is next to it in a cupboard. 

[Deleted User]

 I get the exact same thing at least twice a year and the water board has to come out and clear the communal sewer that runs through our gardens. They use a huge suction hose and poke around a bit. Have blamed baby wipes and nappies, could be anyone in the street. 

Silvertabby

_shel said:

 I get the exact same thing at least twice a year and the water board has to come out and clear the communal sewer that runs through our gardens. They use a huge suction hose and poke around a bit. Have blamed baby wipes and nappies, could be anyone in the street. 

We had this a few years ago (but luckily not as bad - houses rather than flats?).  Turned out the new parents a couple of doors down assumed that disposable nappies = flushable.  The whole street heard granddad casting doubt on offspring's common sense and waste of uni fees and it never happened again.

Apodemus

hampshirebabe said:

Thank you for your help so far, from what I've read I think it is a problem with the vent pipe, but I'm not sure where it is. These are the external pipes, there's a small plastic pipe just behind the toilet, or there are several covered ventilation pipes, I'm guessing it's the top one, but nit sure how to get up to it.

I'm not sure any of these will be the vent. It is quite possible that you have an internal valve that is stuck shut (Google durgo valve). Normally it would open when you flush, allowing air to enter the pipe and allowing everything to fall away under gravity. With the valve jammed open you would get smells in the house, with it jammed shut you would get the symptoms you are seeing. It may be in a shared loft space or a wall cavity.

Jeepers_Creepers

Yup, none of these 'pipes' is a 4" soil vent pipe. I guess it must be internal - where does the toiler soil pipe go? In to a boxed-in wall section?

Can you get further away from the house and take a phot showing the roof slope? Any pipes sticking out from there?

Rosa_Damascena

If it's a leasehold property I would leave it to the LL / freeholder.