A water leak sensor is a small battery device that sounds an alert when it touches water. It is one of the simplest checks you can add to a house you are watching from far away, but only if placement, alerts, and response are set up together. This walk-through goes from the first look to the final test.

Local option: New Plan Care gives families in the St. Louis area in-home help so a parent can stay home: companionship, help with bathing and dressing, meals, and overnight care. Call (314) 405-0887.

Step one: find where water starts

Walk the house with a flashlight and look for the low spots: under the kitchen sink, behind the toilet, beside the water heater, at the base of the washing machine, and under the dishwasher. Choose the two or three spots where a slow leak would reach the floor first. Note any spot where a pet's water bowl or a mop bucket might set off false alarms.

Step two: prepare the surface

Wipe each spot dry and clean. The sensor needs flat contact with the floor, so move any rug edge or tray that would lift it. Check that any cable from a probe-style sensor will not be pinched by a cabinet door or drawer.

Step three: pair and name it

Set up each sensor on its hub or app and name it by place, such as under kitchen sink, so an alert tells the responder where to go. Check that the battery reads full before you leave the spot.

Step four: test it on purpose

Place a damp cloth on the sensor and watch for the alert. Confirm the alert reaches every phone on the list, including the phone of the person in St. Louis who will respond. Then dry the cloth and confirm the alert clears when the sensor dries.

Step five: set who responds

Name the person who gets the first alert, the second person who gets it if the first does not reply, and the local person who can shut off the water if needed. Write the shutoff valve location on the same page so no one has to search for it during an alert.

Step six: keep the test on a schedule

Set a monthly reminder to test each sensor and check its battery. Write the test date in the house folder. A sensor that has not been tested in a year is not doing its job.

Check these tonight

Count your sensors and the spots they cover. Confirm the alert list includes a phone you can answer from an airport. Ask the St. Louis helper to show you where the main water valve is and to photograph it.

What to take to the doctor

Nothing here needs a doctor's visit. If your parent has had a fall near a wet spot or uses a walker on damp floors, mention it at the next visit so the care team knows about the setting.