Kitchen waste plans

[DanGB]

Hi all,
Doing up my ktichen of my recently purchased house, and also taking the opportunity to move an appliance and possibly re-jig the waste pipes.

This is how the kitchen was currently:

Here are my plans:
-The washing machine is being moved
-Also, im planning to move some of the waste pipe inside the house rather than keep most of it outside like it is now, this is just to tidy the outside of the house.
Why would of they of run the pipe on the outside, due to easy access?

Its all currently 40mm pipe

Should I need any anti syphon traps?

What do people think of the plan, any possible issues? I think the only thing I would loose is the access trap at the top on the outside.

The run has a decent gradient, would it be an advantage to make it even steeper?

Thanks.

 

[Madrab]

Outside for ease of installation probably.

Can't see any issue with that, try and keep the fall to around 45mm per m. You are above recommended length of run but if you haven't had any issues with it up to now then it should be fine. If anything I'd maybe look at making the run in 50mm after the sink to minimise the chance of syphoning the sink trap, and put a rodding access at the 2nd elbow

 

[DanGB]

Outside for ease of installation probably.

Can't see any issue with that, try and keep the fall to around 45mm per m. You are above recommended length of run but if you haven't had any issues with it up to now then it should be fine. If anything I'd maybe look at making the run in 50mm after the sink to minimise the chance of syphoning the sink trap, and put a rodding access at the 2nd elbow

Great, many thanks for the reply.

I know there is a minimum recommend fall rate, but is too much fall bad, if I increase the fall rate?

 

[denso13]

I know there is a minimum recommend fall rate, but is too much fall bad, if I increase the fall rate?

It's worse if there are solids in the water but shouldn't be too much of a concern in a kitchen.

 

[Madrab]

As Denso mentions not too much an issue in a kitchen. The min/max fall is to ensure that the waste is self cleaning but not too many solids in a kitchen waste.

Only thing I might add is that if the water velocity is too high on a long run with a few elbows that it could create a vacuum in the run and can pull on the traps upstream making them gurgle.