The short answer
Smart water leak detectors come in three kinds, and they do very different jobs. A sensor on the floor beeps and texts you when it gets wet, but can’t stop anything. An actuator clamps onto your main shutoff valve and closes it when a sensor goes off. An inline monitor is plumbed into the main line, watches every gallon, and shuts the water off on its own when something bursts. For a Northern Virginia house with a finished basement, or anyone away for a week at a time, the shutoff is the one that saves the floor.
Is it worth it? The things that flood houses here are mostly a washer hose, a toilet supply line, a water heater or a pipe that froze (the parts that flood houses), and every one of them does the most damage when nobody’s home. A shutoff is a warning light that also acts, which most of the warning lights and error codes in a house can’t.
The three kinds
Swipe to see all columns →
Swipe to see all columns →
| Kind | What it does | Catches | Misses |
|---|---|---|---|
| Spot sensor | Sits on the floor and alerts your phone when water touches it | Water in that one spot | Anything a few feet away. It can’t stop the water. |
| Valve actuator | A motor that clamps onto the handle of your main shutoff and turns it closed when a sensor trips | Whatever its sensors catch, and it stops it | Leaks where there’s no sensor |
| Inline monitor and shutoff | Plumbed into the main line. Measures flow and pressure, learns your normal use, and closes its own valve | Bursts, flows that run too long, and small drips through a pressure test | Drain leaks, groundwater and roof leaks |
The inline kind is the only one that catches a leak nobody put a sensor next to. Most run a test about once a day: with nothing running, the valve closes for a few minutes and the monitor watches the pressure. If the pressure drops, water is getting out somewhere, even a drip inside a wall.
$29 Water Test and Plumbing Safety Check
A licensed plumber tests your water's hardness at your kitchen table, in grains per gallon, checks your water heater's age and health and walks the plumbing with photos. Book the $29 test
What it won’t catch
- Drain leaks. A leaking shower drain or toilet seal only leaks while water is in use, which looks like a normal shower to the monitor (ceiling leak under a bathroom).
- Groundwater and the sump. Water coming in from outside never went through the meter. A sensor next to the sump pit is what warns you (sump pump not working).
- Rain. Roof and window leaks, for the same reason.
- A sensor in the wrong place. A spot sensor only feels what’s under it.
Where the sensors go
- Under the water heater, in the pan or on the floor beside it (water heater leaking from the bottom)
- Behind the washer
- Under the kitchen sink and the dishwasher
- Behind the fridge if it has an ice maker
- Beside every toilet and under every bathroom sink
- Next to the sump pit
- By the furnace, where a humidifier or a condensate pump drains
What a shutoff needs
An actuator needs a quarter-turn ball valve on the main, the kind with a lever handle. If yours is an old gate valve with a round wheel handle, it has to be replaced first, and it probably should be anyway, since old gate valves often don’t close all the way (finding your shutoff valves).
An inline monitor gets cut into the main line inside the house, right after the main shutoff, sized to your pipe. Most houses here are 3/4 inch or 1 inch. It needs an outlet nearby and Wi-Fi that reaches the basement or the utility room. Ask whether it can still close the valve when the power or the Wi-Fi is out, and how it reaches you if it can’t. If an irrigation system runs off the same line, the monitor has to be set to expect that flow. And ask your insurer: some give a discount for an automatic water shutoff.
Having one put in
SwiftPro’s plumbers install the Moen Flo inline shutoff, in 3/4, 1 and 1-1/4 inch, and the Resideo L5, a Wi-Fi actuator that comes on its own new ball valve, cut into the main. The price depends on your pipe and which one fits, and it’s in writing before we start. If the main valve is an old gate valve, we replace it in the same visit. Our Water Test and Plumbing Safety Check is $29: a licensed plumber walks your plumbing with photos, checks the water heater and tests your water’s hardness at the kitchen table. It’s a good way to find out what your main valve and lines look like first. Booking a plumbing repair? The whole-house plumbing inspection is included, so the next drip gets caught too.
Get a plumber on it
Book a plumber online, call (703) 997-9757, or book the $29 plumbing safety check. We answer day or night. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Questions people ask
Do smart water leak detectors work?
The sensors work well at the spot they sit on, and alert your phone. They can’t stop water on their own. A shutoff, either an actuator on your main valve or an inline monitor, is what turns the water off.
What’s the difference between a leak sensor and an automatic shutoff valve?
A sensor only warns you. An automatic shutoff closes the main water line, either when a sensor trips or, for an inline monitor, when it sees a flow or a pressure drop that isn’t normal.
Can a smart shutoff catch a leak inside a wall?
An inline monitor can, if the leaking pipe is a supply pipe under pressure. Its pressure test sees water escaping with everything off. It won’t catch a drain leak, which only leaks while water is running.
Does a smart water shutoff need Wi-Fi?
For alerts and the app, yes. Before you buy, ask whether it can still close the valve during a power or Wi-Fi outage, since a burst during a storm is when you need it.
