Kitchen Waste Water

[Dave Liquorice]

I have a problem. Moving kitchen from one end of a long room to the other. Doorways in the center of both long sides. The move means that kitchen waste water will have to cross a doorway. How can this be achieved?

Thoughts so far:

A pump of some sort but that would be noisy. SWMBO'd doesn't like that, I don't like because it needs power just to empty the sink. We do get power cuts...

I quite like the idea of using swept bends to take the waste down below the (solid) floor level at the door and back up again the otherside in an extended U. Obviously water will remain in that section but that is no different to a trap. There might settlement of kitchen waste over time leading to blockage but I'm thinking that the sheer flow of water from a full sink will simply flush all but the really heaviest bits of crud through. We only use cooking oils, no solid fat goes down the sink. Fairly easy access to this section either for wire rodding or even removal for cleaning outside would be part of the design. The downstream side would have an air admitance valve to stop it being noisy, there would be about 7m of run from the outlet of the U to the stack.

Is this "extended trap" a non-starter? If so what other solutions can people come up with?

[Phil L]

Take it under the floor for it's whole length, and put a rodding eye where it protrudes from the wall outside

[Tim Watts]

It sounds like it might be a recipe for trouble -

but, if knowing that, you design bomb proof access in as you're clearly wanting to, you'll probably be OK.

I made a single mega-U bend out of 2 swept tees and 2 swept bends in 50mm to service 2 adjacent standpipes for washing machine and dishwasher. The tees are arranged so that the inflow and outflow swept in the sides and the tops of *both* tees had screw blanking caps on.

All solvent welded and works brilliantly.

Now your disadvantage is that yours will be a lot wider so possibly more likely to accumulate crud.

However, if you have top rodding access from both sides, and you do it in 40 or 50mm, even if you get the odd clag up, it will be very easy to attend to.

If there is really no other way, I'd favour it over an active system with a pump (which will go wrong at an inconvenient time).

[NT]

Its doable to run it under the doorway. It will surely block one day, but if you put good access in (3 points) and its easily accessible, and the owner knows what awaits one day, then no worries. Do it without good access, and with a house owner that has no clue where to even start, and there will be regrets all round. Very occasional chemical use can remove the main potential blockers: boiling caustic soda eats fat, conc sulphuric acid eats various organic materials. None of this is recommended practice obviously, but its runnable.

If you cant live with that, dont go up or down at all. Where the waste pipe reaches the door edge, fit a pump, aim its outlet at the right angle so the water reaches the other side at the same height, and fit a hopper there. Fit a small float switch in the waste pipe to run the pump, and to avoid trouble, wire a red traffic light to the pump so noone uses the doorway at the wrong moment. :)

NT

[Dave Liquorice]

I did say solid floor. Hacking 4" wide 4" deep trough across the doorway isn't a big deal doing the same for 5m+ and still having the pipe above floor level at the high end due to the required fall and the level of the stack conection seems a bit too much like hard work.

Nothing goes outside, the stack is internal. Though I didn't mention that.

[Dave Liquorice]

This is my house that I intend to only permenantly leave when I'm in a box. I like to think I have half a clue. B-)

I'm thinking of swept T's with the branch being the in/outlets and a stand pipe connected to the top of the outlet with an air admitance valve. Remove the valve to allow wire rodding down into the U from the less wet side should it ever become blocked. The top of the T on the inlet side would be capped but without the stand pipe. This allows access from that end if required and the whole U T's etc would be made from solvent weld as a complete removeable unit using "universal" compression onto stubs from the T branches to connect to the rest of the pipe work.

Not on mains drains, septic tank so a little cautious about the use of strong chemicals.

[Dave Liquorice]

It's sink waste so would be 40mm (1 1/2") to start with. I was actually thinking that reducing to 1 1/4" through the extended trap might encourage a higher water velocity thus carry heavier bits of crud but my fluid dynamics isn't good enough to know if that would actually apply. Or if it did would the smaller bore and thus less crud build required to block it negate the faster flow.

Aye, I like KISS and passive. If this extended trap did block big time and clearing it even after removal was going to take a while for some reason. I'd have a length of pipe that could fit between the two compression joints above floor level. OK we'd have to use another door to get out of the house but at least we could do the washing up etc as per normal.

[Grimly Curmudgeon]

I'd prefer a warning buzzer, flashing light or "Danger! Waste Water" on an LCD display and an electrical door latch. A tingling mat either side of the door is optional.

[Tim Watts]

Here's mine:

me know if you can't see that...

The branch on the left coming towards you is the outfall to the main stack. Going through the facing wall on the left side is the connection for the kitchen sink. Right of the trap are the two feeds to the standpipes.

I did it like that because it seemed like a good idea to have one trap for 2 appliances as it solves the trap-drying-out problem should only one water using appliance be present. I do have screw cap fittings welded on the top of each standpipe, so it is also possible to cap them off too.

I've checked that trap and it is a clean as a whistle - though it only gets dishwasher and washing machine output, which is probably quite good at flushing fat out.

The reason for being in 50mm was to prevent any chance of back pressure being a problem as the run to the stack is 5m away. In fact, it is overkill

- the 3 inlets combined can take a sum total of 50l/min sustained (I measured it). Being me, I also dry assembled it outside and did some hose tests. That explains the height imbalance on the trap and the little drop section - these mostly nullified backing up from either standpipe due to water going down the other at a high rate - which was showing as a problem without them.

Personally, I think I would stick to 40mm min for yours. You're right, 32mm might well force a higher velocity, but my gut feeling is it will offer too much resistance (how many machines and sinks are you dumping through this?) and be at greater risk of furring up.

I would definately solvent weld all the buried bits too.

With an arrnagement like the piccie above, if it does show signs of clagging, it would be very easy to dose it directly with either acid or bleach (or caustic) as suits the clag, overnight once every few months - that should keep it mint.

and if it doesn't perform, you still have the pump option...

One other thing: might be worth wrapping the buried section in something with give prior to concreting over as 1m buried uPVC will have significant expansion tendencies when hot. I see 1cm expansion in 5m (have to retro fit a sliding joint). I'm thinking it may get stressed if buried in concrete with not movement possible.

Cheers

Tim

[Grimly Curmudgeon]

just today when I had to fit a set. A Chesty Morgan, or a George Patton, perhaps.

[82045]

Aren't they 135s?

[Dave Liquorice]

One washing machine and a 1 1/2 bowl sink, though I might make provision for a dishwasher as well. SWMBO's wants the washing machine in the utilty room but isn't saying how one fits that into the space that doesn't exist...

It won't be permenantly buried or cast into concrete. There would be a removeable lid of some sort and compression joints to enable the whole thing to be removed if poking with a wire didn't clear it.

That thought had already occured to me.

I wonder what building control will think. I'd argue that it's better than a pumped solution as it is passive and has a manual bypass if required. Pump goes wrong or there is no power you have no waste drainage from the kitchen. Manual bypass wouldn't be very good as the ouput from a pump, AIUI, is a much narrower bore.

[TheOldFellow]

I think that I would cut the channel in the concrete at the door plus space for a pushfit swept T at each side, but leave the pipe laying in it with a steel cover. It could be done very neatly with an angle grinder, but it depends of course, on the planned floor treatment.

R.

[Grimly Curmudgeon]

Last time I asked for 135s I got a 'wha?' from the counter bod.