How Far from a Soil Pipe can you locate your Kitchen Sink

[Knightswood]

I've just had a re-think in the design of my house and find that most books indicate that the maximum distance with a 38mm PVC waste is 2.5 m from the Soil Pipe

I'd like to locate the sink 8m from the nearest soil pipe. What should I do?

Run 100mm Pipe under the house through to the kitchen, or is there a much better way?


All ideas will be considered.

 

[masona]

I've just had a re-think in the design of my house and find that most books indicate that the maximum distance with a 38mm PVC waste is 2.5 m from the Soil Pipe

I've seen many waste pipe up to 10m run !! As long you got the fall,I can't see a problem. Did the book explain why ?

 

[DAZB]

How Far from a Soil Pipe can you locate your Kitchen Sink ?

As long as it's in the same street !

 

[penrymmj]

The distance is based upon the need to maintain a level of liquid in the trap. If the pipe is full of water for too long whilst draining it will siphon the water out of the trap, resulting in foul smells coming up from the drains . Bigger diameter pipes will flow will less speed so are not as likely to create suction.

The design of wastes is covered by the dreaded building regs which allow a maximum distance of 1.7m for 32mm pipe, 3m for 40mm pipe and 4m for 50mm pipe without additional venting but depending on the gradient of the pipe (flatter the better). I guess that strictly speaking it should be covered by a building control inspection

You could increase the distance by venting the waste pipe with a separate pipe which must be at a higher level than the water level in the sink. This would break any suction trying to pull water from the trap. The vent should be run to outside or could be terminated inside with an air admittance valve.

An alternative could be an "anti-syphon"/"anti-vac" trap, which is designed to ensure that a liquid seal is always present. I have used one in my bathroom. It is more noisy than a conventional trap but no smells so far. I am not sure how an anti-syphon trap would cope with kitchen waste.

For such a long run you may want to consider using 50mm waste pipe.

Hope this helps

 

[Knightswood]

Thank you all for your help.


I'll speak to the Building Control Office.

But 50mm with the special trap will do the trick.