Plumbing waste for washing machine and dishwasher

18 Nov 2005
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United Kingdom
Hopefully my diagram has uploaded correctly - it will make the explanation a lot easier.

I currently have a condensing boiler drain pipe and a washing machine waste pipe connected via separate spigots to the pipe which drains the sink. This arrangement is shown in the upper diagram.

I'm hoping to install a dishwasher and was wondering if the arrangement in the lower diagram would work. I've searched the web for a trap arrangement which has three spigots (i.e. so that I can connect boiler, washing machine and dishwasher), but there doesn't seem to be one out there.

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When I try to expand you picture I get a message saying I don’t have permission to view it :confused: ; but I think I get the jest of it.

The boiler connection is only a condensate drain & so should not cause any problems, cant you re-route that to outside? The problem I can see is that you may get siphoning when one or other appliance empties if you happen to be using both at the same time & if both try to drain at the same time, it probably won't cope.
Thanks Richard.

Fixed the link to the image so you should be able to view it now.

In understand your point regarding syphoning, but wouldn't the non-return in-line valves prevent this?

I also note your point on running the condensing pipe directly to the outside. However, as we live in a flat (not ground floor) I'd prefer to avoid this if at all possible as I'm not very good on ladders!
i cant tell from the pic the actual dimensions so i can offer 2 solutions that might work,
1 would be if possible get an washing machine T which has a spigot, remove the existing trap, cut the pipe and lower it and fit the washing machine T in the gap giving you 3 seperate outlets, if not possible to cut it down enough and you go for the option in your pic i would suggest you alter the pipes so that the boiler condense and dishwasher go into the double spigot as there wont be as much condensate volume so shouldn't cause a prob going down the single spigot with the dishwasher, and put the washing machine on its own as it empties via the pump, check McAlpine website for T and other trap options and you will find something
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, check McAlpine website for T and other trap options and you will find something

They wouldn't happen to sponsor you would they? :LOL: :LOL: :LOL:
i wish!! no such luck, but i have always found their gear very good quality, not like some other multifit fittings that dont seem to fit the pipe i'm trying to put it on, even if it is a bit more to buy i would stick with it cause it does what it says on the tin, and i have no qualms putting it in where it will be covered over, in saying that i done a job for a mates mum a few months ago, (stripped bath out to fit a shower) and the old waste pipe was Bartol push fit that i had fitted (we reckoned about 27 years ago when i put in a bathroom suite for them just after i got married) was still absolutely solid and looked as if it would have lasted a while yet
In understand your point regarding syphoning, but wouldn't the non-return in-line valves prevent this?
That was detail I couldn't read on your original link :rolleyes: . I'd go along with Kirkgas sugestions ;)
Thank you for the replies.

Don't think there is enough length in the vertical piece before the u-bend/trap to install another T-junction with spigot.

I'll give the second option a go, i.e. dishwasher and boiler condensing pipe via non-returns to y-connector to 1st spigot and washing machine on its own to the second spigot.

Thanks again.

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