Can kitchen sink & dishwasher waste feed to main sewerag

[JP_]

Or should it be totally separate to prevent risk of blockage / backflow?


Builder has suggested running new kitchen waste to the sewerage downpipe that is in the room rather than digging up the front garden and tarmac drive to access the sewer direct. But my plumber questioned this - he admitted that he was not sure, but was concerned that if for some reason the sewer got blocked then poo would come un in the kitchen sink when we flush the loo.


What would be the correct thing to do?


Builder quoted £150 for the drainage works, said it would cost about £1000 to go outside, dig trenches through drive and put everything back. Maybe an investment worth making?

The kitchen sink and dishwasher are about 6 metres from the main soil pipe. It will be a long run.

Here is the plan the architect drew up - it shoes the sink connected to the soil pipe, which suggests it is OK. However, the sink is now going to be at the bottom of that image in the window area:

 

[denso13]

Connect to the SVP, no issue with that, could be 50mm if a long run.

 

[Nige F]

Builder has suggested running new kitchen waste to the sewerage downpipe that is in the room rather than digging up the front garden and tarmac drive to access the sewer direct. But my plumber questioned this - he admitted that he was not sure, ]

Your plumber is not sure How much plumbing has he done - that`s 1st. year apprentice stuff

 

[JP_]

He's been plumbing for 20 years, but does mostly gas and water pipes on new builds I think. He said he thought it was OK, but worth double checking what the builder is planning!

 

[Hugh Jaleak]

No issue with connecting sink to soil pipe, it's a common practice. Without knowing the drainage runs for the property it's difficult to suggest an alternative, but if sink is being moved it may be closer to the ground floor W.C. than the soil pipe, is draining the sink to there an option?

 

[newbuildinstaller]

I would specify the following

A NEW "plumber"

yes its fine

 

[Nige F]

He's been plumbing for 20 years, but does mostly gas and water pipes on new builds I think. He said he thought it was OK, but worth double checking what the builder is planning!

A Gas Man : No worries - I like to wind them up . Thing is you`ll need a 50mm waste, as stated here before - and I would check the gap behind the floor units backs to the wall because it might be tight In fact I would carcass the waste in with it clipped to the block wall before it`s plastered . Also fit a small diameter Air Admit. Valve on the head of the run , and put in some access tees ( and have them coming through the cupboard backs ) for cleaning with a sani snake if needed in future

 

[chirpychippy]

A certain German kitchen manufacturer I fit kitchens for always insist we batten the walls off for base units for 50mm to overcome problems like this where the service gap is to small. But, you would need an absolute minimum of 650mm worktop (laminate) unless you having granite or corian then the worktop will be templated anyway for whatever depth.