Washing machine hot water dead leg

YorkshireMidge · 1 Apr 2020

I've just stumbled across an old hot water pipe coming out the wall behind the kitchen units which due to its position, must have been an old washing machine outlet from the days when you tended to have both hot and cold.

It's very difficult to be certain without ripping holes in the plaster, but it's looking like it could be a dead leg about 20 inches horizontally from the kitchen hot tap, and a further 3 inches out the wall and down to a cap, where the washing machine valve would have been.

My assumption is even in a hot water pipe, the temperature might not rise enough in a dead leg to kill off any bugs.

It's going to be a pain to cut it out and I wondered about sticking a drain point on it and just drawing the water off from time to time, but I wasn't sure how frequently that would need to be done.

Thanks.

sircerebus666 · 1 Apr 2020

Have you found where it connects into the hot feed pipework (I'm assuming it tees off somewhere) ?

I would disconnect it there if you are worried.

How long has that dead leg been there do you know?

YorkshireMidge · 2 Apr 2020

sircerebus666 said:
Have you found where it connects into the hot feed pipework (I'm assuming it tees off somewhere) ?

I would disconnect it there if you are worried.

How long has that dead leg been there do you know?

Thanks for the reply. As I mentioned, I'm going to have to cut out plaster to be certain as the pipe run is buried but its looking like it tees into where the pipe for the kitchen tap emerges from the wall. Access to the kitchen tap pipe is really tight. I reckon I might just be able to get an oscillating tool in to cut the dead leg and cap it close enough to the tee not to be a problem but I just don't know yet, hence the question. As for how long, we must be talking many years with no ill effects - but now I've found it, it is the sort of thing I'd want to sort one way or the other.

Mottie · 2 Apr 2020

That’s made me have a look at mine - I’ve never really thought about stagnant water in there. I have a hot dead leg too with a washing machine connector on it. It’s about a 6” branch off of the pipe that goes to the hot tap. Been like that for at least 15 years. Worth removing or just leave alone? Something to do would be great!

terryplumb · 2 Apr 2020

Cut it out then forget about it is the short answer.

YorkshireMidge · 2 Apr 2020

After a bit more cutting and digging, it's definitely a dead leg and measures in at 2ft. Having another look at where any valve would end up, even the idea of drawing water off isn't going to be feasible - so am going to have to fight my way through the other plumbing and cut it out. Thanks for the replies.

Madrab · 2 Apr 2020

Don't worry yourself about a 2ft dead leg, especially on the hot water side of things. If you can easily remove it then do but I wouldn't get overly worried about it if you can't.

Harry Bloomfield · 2 Apr 2020

YorkshireMidge said:
After a bit more cutting and digging, it's definitely a dead leg and measures in at 2ft.

A 2foot dead leg in a pipe, especially a hot pipe isn't something to be worried about. There will be some circulation through it anyway, as water is drawn past it. You shouldn't be drinking or brushing your teeth in water from the hot taps.

Mottie · 2 Apr 2020

Harry Bloomfield said:
You shouldn't be drinking or brushing your teeth in water from the hot taps.

Whoops! I thought when I went from gravity hot water to unvented, it was safe to do so as it’s effectively sealed mains water and not water from a tank in the loft. I’ve been filling the kettle and pans to cook food in from the hot water tap.

YorkshireMidge · 2 Apr 2020

Harry Bloomfield said:
A 2foot dead leg in a pipe, especially a hot pipe isn't something to be worried about. There will be some circulation through it anyway, as water is drawn past it. You shouldn't be drinking or brushing your teeth in water from the hot taps.

Fair point - esp. as ours is gravity fed still so I don't consider it as potable anyway.

Harry Bloomfield · 2 Apr 2020

Mottie said:
Whoops! I thought when I went from gravity hot water to unvented, it was safe to do so as it’s effectively sealed mains water and not water from a tank in the loft. I’ve been filling the kettle and pans to cook food in from the hot water tap.

In that case, it should be OK, but seems a bit of a waste to be firing up your boiler for such a tiny amount of warm water.

Mottie · 2 Apr 2020

Harry Bloomfield said:
In that case, it should be OK, but seems a bit of a waste to be firing up your boiler for such a tiny amount of warm water.

It’s stored hot water, not a combi.

Madrab · 2 Apr 2020

Mottie said:
Whoops! I thought when I went from gravity hot water to unvented, it was safe to do so as it’s effectively sealed mains water and not water from a tank in the loft. I’ve been filling the kettle and pans to cook food in from the hot water tap.

Don't worry too much about it, if you use the hot water regularly and it's held at at least 60deg then it shouldn't really be an issue (I do it too), especially if the water is getting boiled by the kettle/cooking.

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Washing machine hot water dead leg

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