Can I use CH cold water pipe to feed a washing machine?

15 Apr 2024
Reaction score
United Kingdom
I recently replaced my old tank bolier to a combi. This left a space that could fit my washing machine. (means I can finally have a dishwasher in the kitchen!)
There is an electrical socket in reach and fellas that fitted the boiler were kind enough to over size and graduate the waste pipe to accommodate the washer waste.

Is there any reason why this would not work? Thank you for advice.


  • 20240409_094439.jpg
    263.3 KB · Views: 105
  • 20240409_094458.jpg
    334.3 KB · Views: 94
Sponsored Links
What on earth is a central heating cold water pipe?

Are you meaning the mains water pipe which feeds the boiler? If so, probably yes but it will affect the boilers output when the washing machine is filling.
Is the photo the proposed location for the dishwasher? If so it looks like there are pipes in the way.
If its a mains cold water pipe, you can T into it to feed the washing machine. Will it affect hot water supply from the combi boiler? Probably but only occasionally and briefly if the the washing machine fills when someone is using hot water but this will likely be the case wherever the washing machine supply is taken from.
Sponsored Links
Are you sure you have the right pipe?

The cold feed to the boiler is the top one in the first picture, entering the boiler second right.
Yup, +1 the pipe you are indicating as cold water in pic 2 looks like it is the HW outlet, the cold supply looks to be the one you can just see the elbow of, top left, in the under counter space.
Yes, I did mean cold water main.
Yes , I did point to the wrong pipe.
And no, the pipes coming out of the floor still leave plenty room for the washer.

Thank you for your replies and confirmation that it will work. Now just need to find a good plumber.
Who on earth ty-raps a waste pipe to gas and water pipes rather than installing suitable proper pipe clips and spacers (i.e. do the job properly)? (Especially important once a washing machine waste standpipe is added into that pipework, I'd say).

What is/was that capped off copper pipe in the second pic for?
Honestly, I've no idea... As I am someone with no plumbing knowledge, hence my original question, can you please explain why what you said would be important for the washer? So I can ensure the plumber I get does it properly? Thanks
Waste pipes must be properly supported, as water is heavy, and unsupported pipes will move and leak if they are not fixed properly.
If the smaller white plastic pipe from the boiler leaks, what's inside is corrosive and will damage anything it leaks onto.

Washing machine waste hoses usually hang into the appropriate waste pipe, which will add yet more weight, causing anything not fixed to fall to the floor.
Your washing machine will then fill continuously while all of the water flows out on the floor.
Thank you for your advice... I will ensure the waste pipe is supported.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links