The best smart water shutoff valves

Who this is for

A smart shutoff is the one device that turns a water loss from a $20,000 rebuild into a wet floor. We say that as the crew that gets the call after the fact. On the losses we work, the difference between a two-day dry-out and a gutted first floor is almost never the size of the leak. It is how many hours the water ran before someone turned the handle.

This guide is for three kinds of homeowner:

• You leave the house. Second homes, long work trips, snowbirds. Nobody is there to hear a sensor, so the valve has to close on its own.
• You have old plumbing or a finished basement. Galvanized supply lines, 1970s copper with pinholes, a slab home, or a basement with drywall and carpet over the sump. One pinhole at 60 psi puts out a few gallons an hour, around the clock, inside a wall.
• Your insurer asked for one. Farmers says that in some locations a leak detection system is required when it insures homes with older plumbing, and Nationwide, Mercury and others run discount programs. The device can pay for part of itself.

If you only want a loud beeper under the sink, you want our water leak detector guide instead. If you want the valve, read on.

Compared at a glance

Four devices, two completely different ideas. Flo and Phyn go in line on the main and watch every drop. Flume watches the meter from the outside. YoLink does not watch water at all; it watches sensors and cranks your existing valve.

How to choose

Flow-based detection catches the leaks sensors never see

A point sensor needs a puddle. Most expensive water losses never make one where a sensor sits: supply lines inside walls, a slab leak under the kitchen, an irrigation break at the side of the house, a toilet fill valve that runs all night. Flow monitoring on the main catches those because it does not care where the water goes. It only cares that water is moving when nothing should be on.

This is the core difference between an inline monitor and a sensor-triggered valve. Moen states Flo runs a daily microleak test and identifies leaks as small as a drop per minute. Phyn pairs an ultrasonic flow sensor with pressure-wave analysis that recognizes fixture signatures. Flume watches the meter register itself, which is the same flow the utility bills you for. YoLink and Resideo cannot do this; they only know a leak exists when a sensor touches it.

A practical test: a running toilet wastes roughly 200 gallons a day. On a Flo or Flume you see a flat continuous draw on the usage graph within hours. With sensors alone you find out on the water bill.

Pressure micro-leak tests find pinholes before they are leaks

Flo and Phyn can close the valve briefly, usually overnight, and watch the pressure in the house side of the plumbing. If pressure decays with every fixture off, water is leaving the system somewhere. Moen calls it a microleak test; Phyn calls it a Plumbing Check and says it finds hidden flaws like poor seals and pinhole leaks. A weeping compression fitting under a vanity, a seep at a water heater nipple or a pinhole still small enough to self-seal with mineral deposits will all show up as a pressure drop long before they show up as a stain.

Flume cannot do this because it never touches the pipe, and YoLink and Resideo have no pressure sensor. If you own an older home with original copper or galvanized, we weight this feature heavily: it is the closest thing to an annual plumbing inspection you can automate.

Install: pro vs DIY, pipe sizes, power and Wi-Fi

Inline monitors (Flo, Phyn, Resideo L5) are a plumber job. The main line gets cut after the meter, the shutoff and the pressure-reducing valve, and the device goes in with unions so it can come out later. Moen recommends a licensed plumber; Phyn does too and quotes one to two hours. In the Puget Sound market we see plumbers charge in the range of a few hundred dollars for the install when the main is accessible and copper or PEX. Galvanized, a buried main or a cramped crawl space costs more. Get a quote before you buy the device.

Measure your main before you order. Most single-family homes are on 3/4-in; larger homes and newer builds are often 1-in; some are 1-1/4-in. Moen sells Flo in 3/4-in (900-001), 1-in (900-006) and 1-1/4-in (900-002). Phyn ships 1-in NPSM ends and you buy adapters for anything else, up to 1-1/4-in. Resideo's L5 comes in 1/2, 3/4, 1 and 1-1/4-in NPT. YoLink's manipulator fits 1/2, 3/4 and 1-in quarter-turn ball valves only; a gate valve or a T-handle will not work and you would need the motorized valve option instead.

Power and battery backup. Flo needs an AC outlet within its 10-ft cord and Wi-Fi at the main; Moen does not list a battery backup. Phyn ships a 12-ft cord and states the valve remains in whatever state it was in when power is lost, with a manual shutoff tool on the bracket for outages. If your main is in a crawl space with no outlet, add an electrician to the budget or put the device in on a UPS. The YoLink controller runs on four AA batteries and the device-to-device pairing works locally, so YoLink states the valve still closes with the power and internet out. That is the only battery-backed shutoff in this group.

Wi-Fi reach in basements. Every inline unit here needs 2.4 GHz Wi-Fi where the main enters the house, which is usually the worst corner of the basement or the crawl space. Phyn's own FAQ tells you to add a repeater or extender if the signal is weak. Check signal at the meter with your phone before you schedule the plumber. Flume splits the problem: the sensor at the meter talks 915 MHz RF to a Bridge you plug in indoors near the router. YoLink uses LoRa between sensors, controller and hub, rated at a quarter mile open air, so the hub can sit upstairs.

Subscriptions

None of the four picks require a subscription for automatic shutoff. Moen says the Flo app is free with no fees or subscriptions required; FloProtect is optional at around $5 a month and buys a five-year extended warranty and a deductible guarantee of up to $5,000. Phyn offers no plan at all. Flume states there are no monthly fees for devices bought direct. YoLink automations run in the free app. Where you will see a monthly cost is in bundles sold through utilities or insurers, such as the FPL Home WaterShield program in Florida that packages a Flo with monitoring for a monthly fee. Read what the fee covers before you sign.

Insurance discounts

We only name programs the insurer or the manufacturer documents in public. As of October 2026:

• Farmers names the Moen Flo Smart Water Monitor and Shutoff on its leak-detection page, says installing one may earn a significant discount, and notes that discounts and eligibility vary by state.
• Nationwide runs a smart home program with a free LeakBot leak detector and a policy discount (10% on water and theft coverages in California, 5% across perils in Washington per its own footnote; not available in every state), and Phyn runs a Nationwide bundle page with 15% off Phyn Plus installed at the policy address.
• Mercury Insurance gives policyholders 25% off a Flume and a homeowners discount after install in nine states, on HO-3 policies.
• Chubb clients get 15% off Phyn products through Phyn's Chubb page; Chubb states the offer is not an indication that coverage is available.
• Amica has announced programs with Flume and Phyn.
• American Family says a smart water leak detector could qualify you for a policy discount and sends you to an agent.

Moen puts an insurance verification letter in the Flo app for you to send to your carrier. For the full table, state notes and how to document your install, see our insurer discount database.

Pairing with point sensors

The strongest setup is both: a flow-based valve on the main plus sensors at the appliances that fail fastest. Moen's Smart Water Detector pairs with Flo so a wet pan under the water heater closes the main. Phyn's help center walks through configuring the Phyn Smart Water Sensor to have Phyn Plus shut off the water. YoLink is sensors-first by design. Flume has no sensor integration; it is a monitor only. Put sensors at the water heater pan, washing machine, under the kitchen sink, behind the refrigerator, in the HVAC drain pan and at the sump pit high-water line. Our leak detector guide covers placement in detail.

What we skipped and why

Resideo L5 Wi-Fi Water Leak Shutoff Valve. A proper NPT ball valve with a Wi-Fi actuator in 1/2 to 1-1/4-in sizes and a sensing cable extendable to 500 ft. It is a good trade product, but it has no flow or pressure monitoring, and Resideo's own pages did not publish a warranty, power or backup details, so it scores low on coverage. We list it in the database for homes already being serviced by a Resideo installer.

Guardian by Elexa. Another bolt-on valve controller with its own leak detectors and an optional battery backup. Documentation on the manufacturer side was thinner than YoLink's and the sensors are proprietary with no low-power long-range radio, so YoLink took the value slot.

Moen Flo 1-in and 1-1/4-in. Same device, different valve body. Order 900-006 for a 1-in main and 900-002 for 1-1/4-in; everything on this page applies.

Devices sold only with a monthly monitoring contract. Some utility and insurer bundles lock the hardware to a plan. The hardware is usually one of the devices above; compare the plan cost against buying outright.

How we test and score

We have not run these valves on a lab bench and we do not claim to. We install and see them on water losses, we read the manufacturer specification sheets and manuals, and we score each device against the published rubric for this class: flow-based detection (20%), automatic shutoff (15%), warranty (15%), pressure micro-leak testing (10%), no subscription for core protection (10%), battery backup (10%), insurer discounts (10%), no extra hub (5%) and point-sensor support (5%). Every spec comes from the manufacturer; where a manufacturer did not publish a value we left it blank and the coverage figure next to each score tells you how much of the rubric had data. Prices are approximate ranges and change often, so we do not score on price.