Water Coming Up BathWaste into Bath

[Georgie73]

Hello

My nephew is putting in a bathroom for me. Originally there was never a toilet in the bathroom but with modern designs, it was possible to get one in the room.

It is work in progress at the moment. But I am thinking that nephew hasn't got the pipe-work running at the correct angle. When you flush the toilet, a small amount of water is backing up and bubbles out into the bath.

 

[polesapart]

Replace the AAV above the soil branch with an open vent.

 

[Georgie73]

Replace the AAV above the soil branch with an open vent.

Sorry, can you say that again in Laymans? I just want to know what I'm talking about when I speak to my nephew. He told me he needs to 'adjust' something but wasn't specific.

 

[muggles]

The big pipe with the cap on outside needs to be extended up above the soffit (normally by going straight up through the soffit and tiles), and leaving as an open end with a bird guard on it

While you're at it, make him takle that hideous flexible waste pipe out from under the bath and do it properly with rigid connections. That's a massive bodge as it is now, and will cause you problems forever more

 

[Georgie73]

OK. The big pipe on the outside. I didn't want to go up above the soffit so I was told this solution was OK with building regs.

The roof is being rebuilt and the angle increased which will hide the flexible pipe but I will get him to change to rigid connections. The top of the big pipe is vented and that will pop out slightly above the new roof.

 

[Hugh Jaleak]

+1 for Muggles instructions. Bath waste is a blockage waiting to happen. I'm also a little concerned about how that waste has been connected to the stack. There doesn't look to be a boss at that level on the junction, and fitting a strap boss there would be awkward. Please tell me he hasn't just cut a hole in the pipe, pushed the waste in and sealed the gap?

The AAV is a one way valve, will allow air in, but wont vent stale air from the system. Already causing a bit of a problem, or you wouldn't be posting here, whilst it maybe fine with regs, they don't work in every situation. I would also be checking the drain has been laid correctly, for it to be bubbling back through the bath when the WC is flushed indicates to me pressure in being created in the system. Even with an AAV fitted, that shouldn't happen.

 

[bernardgreen]

The bath waste is bodged into the soil pipe exactly where the pressure wave from the flushing toilet hits the walls of the stack pipe. Hence water will be pushed into the waste pipe from the bath. The socket on the side of the soil pipe are above the entry from the toilet.

Re-route the soil pipe as shown in green and join the bath waste to it as far from the toilet pipe as possible.

The pressure wave will be less effective and the slope on the bath waste will add more resistance to water getting to the bath.

 

[Hugh Jaleak]

Looking at it again, it would be far better to bring that stack straight up, and take the WC connection across horizontally to meet it. Will allow you to take it to vent at roof level, missing the airbrick by the window, and also allow you to get the bath waste connected properly at a slightly lower level.

 

[Georgie73]

Looking at it again, it would be far better to bring that stack straight up, and take the WC connection across horizontally to meet it. Will allow you to take it to vent at roof level, missing the airbrick by the window, and also allow you to get the bath waste connected properly at a slightly lower level.

Thank you.

I really don't want the stack going straight up at the front of the house. I can get my nephew to sort out the rest. The airbrick has gone from inside the bathroom. The bathroom has an extractor fan which vents straight out of the roof.

 

[SandyLyon]

Not good practice to install an AAV externally as they can stick Closed in freezing conditions.

+1 with the flexible waste, a problem waiting to happen.

You could replace the shallow seal bath trap with a HepVo valve and 90 deg knuckle Adaptor this would act like an AAV plus would help prevent the back flow problem, but the external stack needs sorting and the dry vent section extending

 

[Hugh Jaleak]

I work for a water company, and on occasions have need to use a truck mounted jetting unit for sewer cleaning. We carry out a lot of PPM, (Planned preventative Maintenance), in areas where problems have manifested before, and/or there is an ongoing issue with silt or particularly, fat, building up. By cleaning it on a regular basis we hope to prevent further problems occurring.

However, we are increasingly finding we are having problems with blowing toilets, and believe me, the bathroom is redecorated in a split second! (Any colour you like as long as its brown!), for the simple reason, folks are replacing or repairing soil stacks, and doing away with open vents in favour of AAV's, and removing the drains ability to breathe.

Vents are and were provided for a reason, if the sewer cannot 'breathe' it will find a way to vent excess pressure or gas. Small amounts of pressure cause bubbling back in traps and toilets, (as with the OP), a large amount, (as in our case when jetting), can be quite catastrophic....

 

[Georgie73]

I work for a water company, and on occasions have need to use a truck mounted jetting unit for sewer cleaning. We carry out a lot of PPM, (Planned preventative Maintenance), in areas where problems have manifested before, and/or there is an ongoing issue with silt or particularly, fat, building up. By cleaning it on a regular basis we hope to prevent further problems occurring.

However, we are increasingly finding we are having problems with blowing toilets, and believe me, the bathroom is redecorated in a split second! (Any colour you like as long as its brown!), for the simple reason, folks are replacing or repairing soil stacks, and doing away with open vents in favour of AAV's, and removing the drains ability to breathe.

Vents are and were provided for a reason, if the sewer cannot 'breathe' it will find a way to vent excess pressure or gas. Small amounts of pressure cause bubbling back in traps and toilets, (as with the OP), a large amount, (as in our case when jetting), can be quite catastrophic....

I think the sewer can breathe. There is another stack soil at the back of the house - the traditional style all the way up past the roof.

 

[Hugh Jaleak]

Fair comment, as long as there's one vent on the property. I'm still concerned though about why flushing the WC would cause back pressure in the bath, this usually indicates a problem elsewhere.

 

[muggles]

There doesn't look to be a boss at that level on the junction, and fitting a strap boss there would be awkward. Please tell me he hasn't just cut a hole in the pipe, pushed the waste in and sealed the gap?

Oh wow, hadn't noticed that on my phone screen. That's really very special indeed. What a bodge. No clips on the waste pipe wither, so it'll sag over time

 

[Georgie73]

Fair comment, as long as there's one vent on the property. I'm still concerned though about why flushing the WC would cause back pressure in the bath, this usually indicates a problem elsewhere.

Could it be air intake? It is a very tiny amount of water that comes back up - realistically, it is nothing more than air bubbles. We think water must be sitting in the bath waste and not draining out properly.