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How to Prevent Flooding in an Upstairs Laundry Room

Ask This Old House plumbing and heating expert Richard Trethewey explains how and why to install an automatic shutoff valve for the washing machine supply hoses.

In this video, Richard Trethewey demonstrates what you can do to a washing machine to prevent a flooding catastrophe. In the United States, the average insurance claim for water damage due to plumbing failures is ten thousand dollars, and one of the worst culprits is your washing machine.

Washing machine hoses usually last about eight to nine years, and if it bursts, it can be disastrous. Now that many laundry machines are found on upper levels, rather than the basement, the risk of severe flooding from burst hoses has increased. The best way to prevent flooding is to depressurize the washing machine hoses when they’re not in use by simply closing the shutoff valves. The issue is nobody ever does that.

Steps to Prevent Washing Machine Floods

1. Shut off the water supply.
2. Cut the hot and cold water lines going into your current shutoff valves. Then, cut the drain.
3. You may need to cut your wall to fit the device.
4. Make the drain connection first, as the drain has less flexibility than the hot and cold lines.
a. Clean and glue PVC together.
5. Cut the existing hot and cold lines to the right length.
6. Connect water lines using stainless steel clamps and PEX couplings by using a PEX cinch tool.
7. The device will be plugged into the wall while the washing machine will be plugged into the device.


Richard replaced the standard hot and cold washing machine shutoff valves with an Automatic Washing Machine Shut Off, which is manufactured by Watts.

The other tools and materials Richard needed to remove the valves and make the new connections, including the braided, stainless steel hoses, the PEX piping and connections, and the PVC glue, can all be found at home centers.