Washing Machine Plumbin

Postby Annie Twotoes » Tue Jul 08, 2008 5:07 pm


A few weeks ago I put in some new kitchen units and new taps etc. Ever since then my water has had a taste a bit like burnt cardboard. The waterboard chap asked me if I have a non-return valve where my washing machine inlet valve plumbs into the water supply to stop dirty washing machine water getting back into the water pipes and into the taps.

I'm pretty sure that I don't - I just have the one cold water inlet pipe plumbed onto the washing machine tap fitting under the sink. It has a filter/trap but I don't think there is any kind of a valve.

I have had a look around but I can't find anything that answers this kind of description - there are non-return valves for the washing machine waste, but not for the inlet.

Does anyone know anything about this? There is not much that has changed between the old plumbing and the new, just new taps, but the washing machine inlet pipe is at a higher level where it comes through the hole in the unit, than where it plumbs into the water supply, so I guess this could mean that water can back-flow into the pipes but I don't know enough about washing machines to know what effect this might have.

Any ideas?

Annie Twotoes
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Joined: Tue Jul 08, 2008 4:59 pm


Simply Build It

Postby Skids » Wed Jul 09, 2008 7:10 pm

Hi Annie Twotoes

All/most washing machines will have what’s called a 'backflow valve/divice fitted inside, therefore there is no requirement to fit a 'backflow device' (sometimes called a single or double check valve)

You would only require this on the pipe if you where fitting a commercial/industrial machine


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Postby Skids » Wed Jul 09, 2008 7:14 pm


You could try turning the isolation valve to the machine, it will have a blue tap on it, off for a bit and see if the water is still affected.
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Joined: Fri Dec 21, 2007 6:35 pm

Postby htg engineer » Fri Jul 11, 2008 8:41 am

I agree washing machines normally have non-return valves fitted internally.

But for the price of them, buy one or two. Fit them to the cold and hot feed if there is a hot feed. Easy to fit.

Get the waterboard back - say right I've done what you said - still no difference. They should sort the problem with the water. Or at least test it to prove there's no impurities.

htg engineer
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Joined: Tue May 22, 2007 5:22 pm

Postby Annie Twotoes » Wed Jul 16, 2008 7:08 pm


Sorry I have been away for a week but thanks for the replies.

The water board actually called me back about this and they said that they will send me a couple of non-return valves in the post, free. The chap that called me said that it was a fairly common problem and that is was something to do with a chlorine build up in the washing machine pipe.

I did try turning the tap to the washing machine off and it did make the water taste better. I also tried the water from the downstairs loo sink, which comes straight from the mains, and that tasted fine too, so maybe the water board chap is right.

I haven't received the valves yet but if there is anything else to report on this I will post it here.
Annie Twotoes
Posts: 2
Joined: Tue Jul 08, 2008 4:59 pm

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