Sink waste to underground drainage?

[flanagaj]

when connecting an internal sink waste to soil pipe, do you have to have a bottle gulley outside or can it simply connect to a sweeping 90 degree bend out through the building and then connect to the main soil pipe with Y joint?  I am anticipating someone telling me that even though it's only a sink that feeds that section, it still needs to be rodable.

 

As we have an ACO drain running around the perimeter, the bottle gulley won't work as it will be pushed further out from the house.

[Nickfromwales]

32 minutes ago, flanagaj said:

when connecting an internal sink waste to soil pipe, do you have to have a bottle gulley outside or can it simply connect to a sweeping 90 degree bend out through the building and then connect to the main soil pipe with Y joint?  I am anticipating someone telling me that even though it's only a sink that feeds that section, it still needs to be rodable.

 

As we have an ACO drain running around the perimeter, the bottle gulley won't work as it will be pushed further out from the house.

It's supposed to be rodable outside, or inside, if solids are present (food waste), but if this is a basin, then you can likely get a deviation from the BCO (if there's one to pacify?).

[flanagaj]

41 minutes ago, Nickfromwales said:

It's supposed to be rodable outside, or inside, if solids are present (food waste), but if this is a basin, then you can likely get a deviation from the BCO (if there's one to pacify?).

It's a kitchen sink, so I guess that will be deemed food waste.  Looks like I'll have to have another IC on the drainage run.

[Gus Potter]

2 hours ago, flanagaj said:

It's a kitchen sink, so I guess that will be deemed food waste.  Looks like I'll have to have another IC on the drainage run.

Post a sketch of what you propose.. that is worth a thousand words. Draw it on a bit oif A4.. take a photo and post.  We won't test you on your drawing  skills!

 

I think you are getting yourself in a bind, the solution is probably simple. 

3 hours ago, Nickfromwales said:

It's supposed to be rodable outside, or inside, if solids are present (food waste), but if this is a basin, then you can likely get a deviation from the BCO (if there's one to pacify?).

This is confusing. Let's see a sketch first. 

 

[Mr Punter]

Tee off the below ground.  Come up to near finish level and use a 110 to 40mm reducer for your sink waste.

[flanagaj]

12 hours ago, Gus Potter said:

Post a sketch of what you propose

 

 

 I cannot propose anything as I am trying to understand how I'd have a back inlet gulley when I have an ACO in the same place.  TA obviously didn't consider this detail.
 

[Russell griffiths]

Easier to stick a 300mm chamber outside, straight from that under walls into a rest bend and then up to floor level under the cupboards. 

[Gus Potter]

 

 

 

On 05/03/2026 at 20:46, flanagaj said:

when connecting an internal sink waste to soil pipe, do you have to have a bottle gulley

Bottle gullies are generally frowned upon these days.

 

 

 

Ok you have posted a sketch but it's not enough detail. Think about how folk that have never seen this before can get their head around things. You can see it but we can't quite get our head around it all. 

 

I've, based on the sketch you have posted, over marked a suggestion for your soil drainage. Let's try and simplify that first. 

 

Here is the theory that lies behind my over marking.

 

When you flush a toilet a "plug of water" goes down the pipe. It causes a vacuum behind it that sucks out water traps, say a sink trap.  But that plug in a 110mm dia pipe rapidly flattens out and let's air pass backwards..reducing the suction. The stack balances all that out as the main thing. If you look at BS codes and the Eurocodes if gives minimum distances between the points of inlet between say a wash basin and a wc connection. This is generally between 150 and 300 mm depending on the type of connection (vertical / horizontal etc. @flanagaj. You have a much greater spacing between the connections. So that problem goes away. 

 

Next is to look at this from the other direction. Say you want to connect a kitchen sink waste into a 110 mm dia soil pipe. The sink pipe after the sink trap can be 40 mm dia or 50mm dia. Here if you chuck a bucket of water down the sink it causes this "plug effect" in the msaller pipe, that breaks the water seal in the trap. The codes say if a 40mm pipe run is more than 3.0 m it can cause this problem. But it looks like where you show an AAV (air admittance valve) the run of the pipe is nowhere near 3.0m thus a standard trap with a 75mm seal and a 40mm pipe at the sink trap should be fine. You have a pop up above the floor still in 110 mm dia and only then change from below ground drainage pipe to above ground pipe, 40 or 50mm dia. 

 

Thus here you can omit the AAV. 

 

If you introduce a rodding point at the end of the drain line you can then omit chambers with INV ( Invert level, the height of the bottom of the pipe called the invert) 122.09m and 122.0m. If you can, move chamber INV 121.69 beyond the corner of the building. This lets you rod in both directions. 

 

Go back and check your drain falls. See, if for the soil the fall is more than 1% ( about 1:50) and for the rain water no more than 1:80. If your workmanship is good then you should be good to go. 

 

Next plot this on a long section. If you set the soil pipes below the rain water pipes by the time you get to the corner the rain water pipe should be above the soil pipe and it can cross over the top of the soil pipe. 

 

Just a last couple of caveats. If the base of the gravel bed under the pipes is below the top of the foundation then check with your SE this is ok. If the top of you pipes are less than 600mm below the ground surface then check the regs in terms of how you protect the pipes. This can be by way of concrete paving slabs as it only looks like domestic foor traffic. 

 

Once you have done that then with a fair wind your Acco channel should sort itself out. You can take it past the main rain water drainage and then return it back and tie into the RWP drainage where it runs down the gable end. 

 

 

 

 

 

 

Edited yesterday at 21:23 by Gus Potter

[flanagaj]

1 hour ago, Gus Potter said:

 

 

 

Bottle gullies are generally frowned upon these days.

 

 

 

Ok you have posted a sketch but it's not enough detail. Think about how folk that have never seen this before can get their head around things. You can see it but we can't quite get our head around it all. 

 

I've, based on the sketch you have posted, over marked a suggestion for your soil drainage. Let's try and simplify that first. 

 

Here is the theory that lies behind my over marking.

 

When you flush a toilet a "plug of water" goes down the pipe. It causes a vacuum behind it that sucks out water traps, say a sink trap.  But that plug in a 110mm dia pipe rapidly flattens out and let's air pass backwards..reducing the suction. The stack balances all that out as the main thing. If you look at BS codes and the Eurocodes if gives minimum distances between the points of inlet between say a wash basin and a wc connection. This is generally between 150 and 300 mm depending on the type of connection (vertical / horizontal etc. @flanagaj. You have a much greater spacing between the connections. So that problem goes away. 

 

Next is to look at this from the other direction. Say you want to connect a kitchen sink waste into a 110 mm dia soil pipe. The sink pipe after the sink trap can be 40 mm dia or 50mm dia. Here if you chuck a bucket of water down the sink it causes this "plug effect" in the msaller pipe, that breaks the water seal in the trap. The codes say if a 40mm pipe run is more than 3.0 m it can cause this problem. But it looks like where you show an AAV (air admittance valve) the run of the pipe is nowhere near 3.0m thus a standard trap with a 75mm seal and a 40mm pipe at the sink trap should be fine. You have a pop up above the floor still in 110 mm dia and only then change from below ground drainage pipe to above ground pipe, 40 or 50mm dia. 

 

Thus here you can omit the AAV. 

 

If you introduce a rodding point at the end of the drain line you can then omit chambers with INV ( Invert level, the height of the bottom of the pipe called the invert) 122.09m and 122.0m. If you can, move chamber INV 121.69 beyond the corner of the building. This lets you rod in both directions. 

 

Go back and check your drain falls. See, if for the soil the fall is more than 1% ( about 1:50) and for the rain water no more than 1:80. If your workmanship is good then you should be good to go. 

 

Next plot this on a long section. If you set the soil pipes below the rain water pipes by the time you get to the corner the rain water pipe should be above the soil pipe and it can cross over the top of the soil pipe. 

 

Just a last couple of caveats. If the base of the gravel bed under the pipes is below the top of the foundation then check with your SE this is ok. If the top of you pipes are less than 600mm below the ground surface then check the regs in terms of how you protect the pipes. This can be by way of concrete paving slabs as it only looks like domestic foor traffic. 

 

Once you have done that then with a fair wind your Acco channel should sort itself out. You can take it past the main rain water drainage and then return it back and tie into the RWP drainage where it runs down the gable end. 

I am slightly confused.  I thought an IC is used for rodding the main drain run, but to also be able to rod the branch line pipework that connects in to the IC.  If I remove the two IC to the West of the building, how would you rod the branches?

[Gus Potter]

29 minutes ago, flanagaj said:

I am slightly confused.  I thought an IC is used for rodding the main drain run, but to also be able to rod the branch line pipework that connects in to the IC.  If I remove the two IC to the West of the building, how would you rod the branches?

I can see where you are coming from. 

 

The main drain run needs a rodding point at the top end. Where it changes direction, down the side of the house at the corner you may want to select a chamber of 600mm dia. Set this a bit away from the wall so you can rod back along the rear and down the side. There is no requirement to have a chamber at each branch line unless the drain line is long, yours is not. 

 

Take your AAV postion, I assume that is your kitchen sink. Now the sink has a grill, then a 40mm trap, then say 50mm ABS pipe that runs into the 110mm dia pop up. Any blockage is going to happen at the trap. 

 

Have you had a look at the regs and the diagrams yet? 

 

 

Edited 23 hours ago by Gus Potter

[flanagaj]

8 hours ago, Gus Potter said:

 

Have you had a look at the regs and the diagrams yet? 

Yes, but they are not very clear.