Plumb Washing Machine

If washday means lugging out the washing machine from under the worktop, connecting it up to taps and hooking the drain hose over the sink, consider plumbing it in permanently.

A fully plumbed-in washing machine not only means that you do not have to move it to use it but also leaves the sink entirely free for whatever else you want. With modern kits, plumbing in a washing machine is not complicated – you do generally not even need to turn the water off.

Washing Machine Connections

A plumbed-in washing machine normally has three connections:

  • One to the cold water supply to the kitchen sink
  • One to the hot water supply (some machines don’t have a hot water supply)
  • One to a waste pipe leading to the drains to take away the dirty water

Plumbing Washing Machine Near The Sink

Read the installation instructions for your new washing machine to check whether there are any special requirements.

Connecting a washing machine to the hot and cold water supplies depends on how close the sink is and, therefore, to the existing cold-water pipes.

You can use self-cutting valves for machines close to or under the sink. These clamp over the existing copper pipes leading to the sink, and, by turning the valve’s body, a hardened steel cutter cuts a hole in the side of the pipe.

Tighten the valve with a spanner. The valve has a threaded connection onto which the end of the washing machine’s water supply hose can be fixed. Water can flow down the hose to the washing machine when the valve handle is opened.

No special tools are needed to fit these kits, but you will have to drill a hole in the side of the cupboard to pass the hose through.

Ensure that the correct hose is connected to the right pipe (i.e. hot or cold) and that the hose is correctly secured to the washing machine before you open the self-cutting valve.

Washing Machine Plumbing When Further Away

For machines further away from the sink, you will have to cut into the pipework to insert a tee fitting, which will mean turning the water off. The cold water can be turned off at the mains stopcock and the hot water at the red or orange handwheel close to the hot-water cylinder.

In either case, run the cold water tap (and hot water tap) until the water stops before making any cuts.

You can cut through the pipe with a hacksaw, but a much neater result is achieved with pipe cutters. You will need a gap in the pipe, the same size as the distance apart of the shoulders in the tee fitting (around 25mm).

Unless the pipe has sufficient slack, this will mean making cuts. Clean up the end of the pipe with a file and wire wool before fitting the tee.

One of the next jobs is to run new pipes (branch pipes) around the wall to where your new machine is located.

Plumbing Fittings

The easiest tee fitting type is a push-fit one, which requires no tools. Put the tee in place, push onto the two ends of the cut pipe, and push a length of new pipe into the upright of the tee to take the washing machine fitting.

The easiest type of pipe to use is semi-flexible plastic pipe, which can be cut with secateurs. Support the pipe with plastic clips and at the washing machine position.

Fit a washing machine valve with a compression fitting to take the pipe and a screwed connection to take the washing machine hose. Connect the hose and turn on the water again.

The next easiest type of fitting to use is a brass compression fitting. You will need two spanners to do this – one to hold the fitting and one to tighten the nut, compressing the olive onto the pipe. If using compression fittings with plastic pipe, fit a metal pipe insert inside the pipe.


The best way to deal with washing machine waste is to fit a stand-pipe (a short, vertical length of waste pipe) to the wall behind the washing machine, into which the waste hose of the washing machine is hooked.

At the bottom of the stand-pipe is fitted a simple trap (U-bend). More waste pipe is taken from the trap through a hole in the wall to the outside drains or kitchen gully.

The waste pipe can be cut relatively simply with a hacksaw (use a file to smooth off the cut end) and is held to the wall with special clips secured with screws and wall plugs. The tricky part of the job is making the large hole in the wall to pass it through.

Short of getting a builder to do this, the easiest way is to use a long masonry drill to make a pilot hole and then enlarge this from either side with a club hammer and cold chisel. Wear safety glasses and stout gloves when doing this, and fill any gaps around the waste pipe with an expanding foam filler.

Make good the wall on the outside with mortar – buy a small pack of ready mix and apply it with a trowel.

An alternative for washing machines close to the sink is to connect the washing machine waste hose to the existing sink waste pipe – provided the washing machine instructions allow this.

This can be done by replacing the existing sink waste trap with one that has an extra connection with a nozzle onto which the waste hose can be pushed.

Washing Machine Electrical Supply

If a washing machine is under a continuous worktop (as many are), there can be a problem connecting its plug to a convenient socket outlet.

The permanent solution is to have a socket outlet below the work surface, wired to a double-pole switch above the work surface, with the cable buried in the wall.

Unless you are skilled in-home electrics, leave this job to a qualified electrician. You can use our free service to get electrician quotes.

Reducing Electricity Bills

Finally, if you have an Economy 7 meter providing cheap-rate electricity at night, fit a plug-in time switch between the washing machine plug and the socket outlet and set the machine to run at night.

You could save £25-£50 a year on electricity.

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