Washing Machine and Dishwasher Combined Waste

[sajid.umerji]

I've got a washing maching machine connected to a waste pipe via a standpipe and p-trap.

I've now purchased a dishwasher and would like to connect the waste from the dishwasher to the existing arrangement by replacing the p-trap with an appliance nozzle trap.

Here's a link to a picture of an appliance nozzle trap:

'll connect the waste hose from the dishwasher to the spigot on the appliance nozzle trap.

But I'm a complete novice when it comes to plumbing, so my my question is: can you think of any reason why this arrangement might be a bad idea ?

I would appreciate any comments.

[Peter Andrews]

When I had a washing machine and a dishwasher using the same standpipe they occasionally pumped out at the same time and the s/pipe overflowed :-(. Twice was enough they are now on separate standpipes, it's probably not a problem if using both on a sink waste though as the sink itself could act as a sump, not ideal but a least it dosn't go on the floor!

Peter

[The Medway Handyman]

Do you mean like this?

I've now purchased a dishwasher and would like to connect the waste

The appliance trap is really designed to replace the trap under the kitchen sink, never heard of them being used to replace the trap on a washing machine trap.

You can get a double appliance trap.

[sajid.umerji]

Thanks guys.

I guess the consensus is that it's a bad idea.

I'll attempt to replace the trap under the kitchen sink with the appliance trap like you suggest, though that's the very thing I was trying to avoid in the first place (due to space restrictions).

Thanks again.

[David Hansen]

On 24 Oct 2006 15:43:57 -0700 someone who may be [e-mail] wrote this:-

That particular fitting won't connect to the existing standpipe, as it is designed to connect to the outlet of a sink.

That transfers the potential problem to the sink drain, where you might be emptying a sink when the machine decides to empty.

Provided the standpipe drains away properly I would fit a tee to the bottom of the standpipe, an elbow and some pipe, to make two standpipes close together. As long as these are tall enough both machines should drain together without problems.

If the existing standpipe doesn't drain too well then I would consider another standpipe running to the stack, as well as sorting out the existing one. Whether this is easier than squashing an appliance trap into under your sink depends on your plumbing.

If you are determined to fiddle under the sink then an alternative to the fitting you are looking at is to fit just an adapter above it like

as with the fitting you outlined you need to be able to lower the pipe that emerges from the trap. If you can't do this then the alternative is either a double sink trap with an adapter like in the second outlet or something like of which lower the outlet pipe from the trap. These are available with one or two hose inlets, either from a plumber's merchant or a handyman shop.

You may find that you end up with several different fittings in your "might be useful sometime" box as you play with the different options. You will then become known in the family as someone who can do plumbing and they will come in useful elsewhere:-)

[sajid.umerji]

Thanks David, I think I'll attempt what you suggest rather than fiddling under the sink.

And as a precaution, I'll try (!) not to run the washing machine and dishwasher at the same time. I think I can be fairly confident that there won't be any problems since the existing standpipe drains perfectly well.

[David Hansen]

On 25 Oct 2006 06:33:51 -0700 someone who may be [e-mail] wrote this:-

I would test it, as it is better to find out under controlled conditions.

By the way a 40mm pipe conveys the waste from my washing machine, dishwasher and sink at the same time without problems. I tested it to make sure:-) However, the various outlets enter this pipe at several places and it has a drop of around 50cm at one point. With anti-vacuum inserts the traps are not emptied by this drop. (from Wickes as it happens)