An automatic washing machine shutoff valve gives you an extra layer of protection against flooding and water damage. It detects when you’re actively washing clothes and only allows water to flow when the washer has a cycle running. Modern versions of the device can even detect leaks and shut off the water supply in advance. In the above video, This Old House plumbing and heating expert Richard Trethewey shows how to install one for added peace of mind—and potentially even lower insurance premiums. Learn more in our guide below.
Preparing for Installation of an Automatic Washing Machine
Before Trethewey begins, he gathers some materials and prepares the site for a safe installation.
Tools and Materials
Besides the valve itself, you’ll need the following tools and materials for a smooth installation:
- 1/2-inch polyvinyl chloride (PVC) pipe
- 90-degree PVC elbows
- Drill/driver
- Hollow-wall anchors and screws
- Pliers
- PVC primer and cement
- Rag (for potential water spills)
- Tubing cutter
Safety Precautions
Before starting the installation, take these safety measures:
- Have a rag handy to catch any residual water in the hoses.
- Turn off the hot and cold water supply valves to the washing machine.
- Unplug the washing machine from the electrical outlet.
Incorporating these precautions can prevent any accidents or damage during installation. It’s also beneficial to inform anyone in the household about the ongoing work to avoid disturbances.
Step-by-Step Washing Machine Installation Process
Most homeowners can complete the installation process in 30–45 minutes.
1. Disconnecting the Existing Hoses
First, Trethewey closes the hot and cold water shutoff valves that supply water to the washer and disconnects the supply hoses from the valves with pliers. It’s best to have a rag ready so you can catch any water that spills from the hoses.
2. Measuring for Cuts
Many automatic shutoff valves come in a kit that can connect to the existing valve with adapters. Trethewey temporarily installs the brass adapters on the existing shutoff valves and inserts 1/2-inch PVC piping into the ball swivels inside the adapters. Then, he attaches 1/2-inch PVC elbows to the brass connections on the underside of the automatic shutoff valve.
Trethewey can now hold the valve assembly against the wall and mark where to cut the straight piping so the valve fits just outside the outlet box.
3. Cutting and Assembling the Piping
Once Trethewey has the measurements and marks he needs, he uses a tubing cutter to trim the pipes to the correct length. Then, he cleans the cut ends and the inside of the elbows with PVC primer.
After everything’s primed, Trethewey uses PVC cement to join the pipe assemblies together, following the manufacturer’s instructions.
4. Mounting the Valve
Automatic shutoff valves can be bulky, so they commonly have space for fasteners. Trethewey makes two marks on the wall over the outlet box, predrills the holes, inserts hollow-wall anchors, and attaches mounting screws to secure the valve assembly in place.
5. Connecting the Water Supply
Now, it’s time to put the hoses back on. Trethewey uses pliers to tighten the two brass adapters, then reattaches the hot and cold water supply hoses to the threaded connections on the automatic shutoff valve.
6. Setting Up the Leak Sensor
The automatic valve Trethewey uses has a leak sensor that goes on the floor behind the washing machine to detect moisture. He plugs it into a designated port and places the sensor in a strategic spot, close enough to detect even minimal water presence.
7. Finalizing Electrical Connections
The automatic shutoff valve has both a power cord for the wall socket and its own receptacle on the front face. When Trethewey plugs the washer’s power cord into the valve, it ties the valve’s position to the washer’s power draw. A light on the valve lets him know the valve is ready to work.
Testing the Washing Machine Installation
Finally, Trethewey reopens the water supply and starts a test cycle for the washer. A light on the valve indicates that the washer is on. If the pressure on the hoses releases when he pauses the fill, the installation is complete.
