How to Plumb In a Washing Machine: Step-by-Step Guide
A clear walkthrough for connecting a washing machine to existing supply and waste, with the checks that prevent leaks, plus when to call a plumber.
Connecting a washing machine to existing pipework is within reach of many confident DIYers. The job is mostly about doing each connection carefully and testing before you walk away. This guide covers a swap where the supply tap, waste outlet and socket are already there. For anything else, see the plumber section below.
Before you start
You will need an adjustable spanner, a bucket and towels, a spirit level, and possibly new hoses and a small tap valve. Check:
- The existing machine is switched off at the socket, and unplugged.
- The cold water isolation valve works and closes fully.
- The waste standpipe or trap spigot is clean and the right height.
- The floor is level and strong enough, because machines vibrate when spinning.
Measure the space and the appliance first, using our measuring guide, so the new machine fits with room for hoses.
Step by step
1. Remove the transit bolts
New machines have transit bolts or brackets at the rear that hold the drum for delivery. Remove them all and keep them, because you will need them if you move the machine again. Fill the holes with the plastic caps supplied. Running the machine with bolts in will damage it.
2. Turn off the water
Close the isolation valve on the cold supply. If there is no valve, you may need to turn off the water at the stopcock, and fitting a valve is a sensible upgrade.
3. Connect the inlet hose
Screw the hose onto the machine's cold inlet and the valve, hand tight plus a small turn with the spanner. Check that the washer is seated. Over-tightening can crack fittings. Use a new hose rather than reusing old ones, since rubber perishes. Modern machines are typically cold fill only, so do not connect to hot unless the model says it can.
4. Connect the waste hose
Push the waste hose onto the standpipe or spigot, secured with a clip. Keep the hose high enough that water does not siphon out, usually within the height range in the manual, and make a gentle loop rather than a kink. The waste connection should have an air gap or vent so wastewater cannot be sucked back.
5. Position and level
Slide the machine into place without trapping hoses. Adjust the feet until it is level in both directions and does not rock when you push the top corners. A machine that rocks will walk across the floor on spin.
6. Plug in and test
Open the isolation valve slowly and check every joint for drips. Plug in, then run a short cycle with no clothes. Check the connections again during the fill and drain phases, with a dry piece of kitchen roll under each joint.
Common mistakes
- Leaving the transit bolts in.
- Reusing perished hoses or a damaged washer.
- Kinked waste hose, causing poor draining.
- A waste hose set too low, so water flows straight out.
- Overtightening fittings and cracking them.
- Not testing under load, which is when leaks often show.
When to call a professional
Call a plumber if you need a new supply or waste connection, if the existing valve is seized or leaking, or if pipes are corroded. Call a registered electrician if there is no safe socket or you need to alter the electrics. Water and electricity should not be improvised. For costs, see how much washing machine installation costs. You can also use Compito to request offers from ID-verified local providers.
Preparing the space and the hoses
Before you start, move the old machine out gently and look at the hoses and valve. If hoses are cracked, bulging or discoloured, replace them. Some inlet hoses are a reinforced type with a stated pressure rating, and a mismatch is not worth the risk. Place a shallow tray or towels under the connections, and have a torch to hand to check behind.
A worked example
You replace a washing machine in a rented kitchen. The old machine was joined to a washing machine valve under the sink. You close the valve, remove the hoses, fit the new inlet hose on the valve and the waste hose over the spigot with a clip. When you open the valve, a bead of water appears at the valve nut. A small extra turn fixes it. During the first rinse, a damp patch shows at the waste clip, so you tighten the clip, then test again. A full test cycle with a dry bit of kitchen roll under each joint gives you real confidence.
Edge cases
- Rented homes: ask before drilling or changing the waste arrangement. Some tenancy agreements restrict alterations.
- Flats: a leak affects neighbours below, so test thoroughly and consider a drip tray or a leak-stop hose.
- Machines in garages or utility rooms: pipes can freeze in winter, so check pipework insulation.
- Moving from an under-counter to a taller machine: the standpipe or waste height may no longer suit.
Safety notes
Isolate the water before disconnecting anything and unplug the machine before moving it. If water has reached the socket or flex, switch off at the consumer unit and have the socket checked by a registered electrician before using it again.
Frequently asked questions
Can I connect a washing machine to the hot water supply?
Most modern machines are designed for cold feed and heat water internally. Check your manual. Some models accept hot, but cold is the common arrangement.
How long should the waste hose be?
Use the length supplied, and keep it within the manufacturer's recommended height. Extending it risks poor draining and strain on the pump.
Do I need a new isolation valve?
If the old one is leaking, sticky or absent, yes. A valve lets you disconnect the machine without shutting off the whole house supply.
Why does my new machine shake?
Usually it is the transit bolts, or the feet are not level. Check both, and make sure the floor is stable.
How can I tell if a slow leak has started after fitting?
Place a dry piece of kitchen roll under each connection and check it after a few cycles and again the next day. A damp patch means a joint needs attention, even if no puddle has formed.