Thicky question - drain pipes

Are any of the joints going to be hidden or are they all accessable? If they are hidden use solvent weld, it won't push apart should you ever need to physically clean the pipe with a rod or springy thing.

At that point I'd use a dismantable joint assuming you have access. So you can get at and open the pipe at that point, again for cleaning blockage removal.

Is 40mm enough for a whole kitchen? We have a long 40mm from the kitchen and it only just copes with sink and washing machine and has blocked once but then one bit only just has enough fall. The Grand Scheme Of Things has this replaced with 50mm...

Dave Liquorice coughed up some electrons that declared:

Hi Dave,

Potentially all accessible (inside a long airing cupboard)

Aye - shouldn't be a problem - kitchen run is dead straight until it hits the wall under the shower room basin, and of course, the junction to the

The 110mm junction will already have access - the top cap will be removable for poking drain wire round the 90 deg bend under the floor (can be poked from the nearby manhole too). This pipe is grey water only - I asked the builder to make it 110 as several drains are running into it and it's hidden behind an under-basin cupboard anyway.

Rather than use an elbow where it comes out under the kitchen sink and up, I'll use a tee with a screw on blanking plug on the horizontal dead-end - this will give me simple and straight-line access to poke a rod right along its length towards the 110.

I'm likely to have a waste disposal unit, so I'm allowing for the fact the poor pipe will have all manner of gunk stuffed through it.

Fall *could* be easily upto 300mm in about 3000mm (1/10) but I'll use a bit less, maybe 1/20

No - I hadn't thought of going right upto 50mm - I must admit I thought 40mm was being generous. But as you've mentioned it I'll have look at that.

Only the run to the bath will be tortuous with limited fall (about 5m and height is whatever a bath trap disgourges at down to as close to the floor level as I can get) with 2 90deg bends - but that pipe will join separately into the 110mm and bath water should have less propensity to block pipes (hair notwithstanding).

Cheers

Tim

Hum, so any leak, even minor, would not be welcomed. Waste water on clean airing clothes, towels, bedding etc?

Very wise. Though kitchen sink waste is anything but grey IMHO, and the grey from a washing machine is full of the filler to bulk up the powders, it was mainly that which blocked our long run...

Yep, good move. See if you can get a cap with a locking screw. Thermal expansion/contraction might make something just screwed on work itself loose over time.

See, not grey. B-)

I'd have to go away and look up what is recomended. 1:10 has a gut feeling of too steep. Too steep the water runs away leaving bits behind, too shallow the water doesn't flow fast enough to caryy the bits. I'd expect the WDU instructions to say what fall the outlet should have.

Depends what is discharging into it just a sink would be fine but sink and something else washing machine and/or dishwasher and it starts to back up if both discharge at the same time. OK you could try not to pull the sink plug when the machines are pumping but you can't control the machines (they could pump together) and sods law will say both will pump just as you've pulled the plug and left the kitchen...

In this case, I would suggest not running it directly into the 110mm, but if you can, have it turn a corner and run down parallel for a metre or two. That fall will generate suction to overcome the long low drop section and speed up bath emptying. Actually, it works really well if you reduce the pipework to

I ended up with a situation like this once (not really by design, just by making use of what happened to be there before), and it works really well. You need an AAV U-trap on the bath and I put a removable rodding cap at the top of the 32mm vertical drop in case it ever blocked at the pipe narrowing, but it never has. When you pull the plug out, you can see the water starts trickling out very unenthusiastically along the long run, and then the suction kicks in when enough of it starts going down the vertical section, and it starts emptying out much faster.

Andrew Gabriel coughed up some electrons that declared:

Interesting idea Andrew. Wouldn't it suck the trap out though?

I wouldn't be able to do it though - I've only got about 10cm of fall total :(

Cheers

Tim

I've used HepVO - no water so no siphonage, no drying out, no need to raise a shower to get a trap under it...

PeterC coughed up some electrons that declared:

In a situation where you might need an air admittance valve as well, these would certainly kill two birds.

Cheers Peter - I'll keep this tucked away - I have possibly one place at least were these would make a lot of sense.

Ta

Tim

Hence the reference to the AAV U-trap (in the bit you trimmed off;-)