Good practice for exterior kitchen-waste pipework

[Chuck]

Hello UK Plumbers

I've sketched the current arrangement for handling my kitchen waste water on the attached diagram. The pipes have become brittle with age (>25 years AFAIK), I don't like the discharge end which tends to get blocked with leaves and wets the concrete before it gets to the gully. Also, it's just used 90° bends at the point the pipes come through the wall so a blockage would be a problem to deal with.

I've had a look at section H of the BR and have come up with a new 'improved' layout, which I hope complies and addresses the problems with the current arrangement. (The condensate is from a new WB 24i with a decent sized siphon so the risk of freezing is fairly low.)

Sketches, to scale, are attached. My specific questions are:

Does my design look okay and comply with good practice?

Is my reading of section H, which is that the discharge should be below the grid but above the water level the gully, correct?

Which brand of 40mm solvent-weld upvc pipe and fittings are best quality for this job? I'd rather spend a bit extra and get something that is likely to last well. I'm in Devon and the wall faces west so it gets quite a lot of sun (and rain!).

Thanks in advance for your advice/comments.

Chuck.

 

[ShaunCorbs]

looking ok to me i wouldn't put an access cap where it comes through the wall, just have it on the up stand for the sink

just below the grid or 1/2 below the grid top

and tbh there all about the same from a plumbing merchants

polypipe or terrain are good

 

[Best]

To be honest, there wasn't much wrong with the original layout if the ends of the pipes had been both put down into the gulley. Often 135degree bends needed to angle down.
I agree with Shaun that I wouldn't use an access cap as no need. Keep it tidy. Also use waste pipe that suits colour of other downpipes etc. If you do not paint the outside wastes then UV rays eventually damage them, although can last well.
Do be aware that someday when that gulley blocks, which it will unless you fairly regularity clean them, then the wastes ends will be into the water in the full gulley and washing machines will pump waste water out of any standpipe inside! Some of the ideas are not so clever in regs. IMO the wastes above the gulley a little and a leaf guard locked in place around it all is the best job.