Moen Flo Smart Water Monitor and Shutoff review

Who should buy the Moen Flo

The Flo is for the homeowner who wants one device at the main to catch the two leaks that cause most of the water losses we dried out: a supply line or appliance that opens up and runs, and a slow drip inside a wall that no floor sensor will ever touch. It watches flow, pressure and temperature on the main, learns the household, and closes a motorized ball valve when something runs that should not. If your insurer has a program for it (Farmers names it on its own leak-detection page), if your main is 3/4, 1 or 1-1/4 in., and if there is an outlet and a 2.4 GHz signal within reach of the line, it is the one to buy.

Who should not

Do not buy it if you cannot have the main cut. Renters, most condo owners and anyone whose main is inaccessible should look at the strap-on Flume 2 or the bolt-on YoLink controller in our smart shutoff roundup. Do not buy it expecting protection in a blackout: there is no battery, and Moen's instructions say the device needs continuous power. Do not buy it if galvanized pipe sits upstream of the install point; Moen says it causes magnetic interference and tells installers not to proceed. And go in knowing that usage-based automatic shutoff is off for the first two to four weeks while the device learns your house.

What it is

The Flo Smart Water Monitor and Shutoff is a motorized ball valve with a flow meter, a pressure sensor and a temperature sensor in one body, installed in line on the cold-water main after the meter, the house shutoff and the pressure-reducing valve. Moen sells it in three valve sizes: 900-001 for 3/4-in. mains (reviewed here), 900-006 for 1-in. and 900-002 for 1-1/4-in. In the box: the device, two NPT threaded brass tailpieces, a wall-mount power supply on a 10-ft cord, O-rings with two spares, grease, an installation spacer and a hex key. Adapters for threaded, solder, press or push-fit pipe are not included.

The software side is FloSense, which learns the home's water-use patterns, and MicroLeak, which runs a daily pressure-decay health test on the closed system. Moen states the system can identify leaks as small as a drop per minute, flags fixtures left running and near-freezing temperatures, and turns the water off automatically if you do not respond to an alert. The app is free with no fees or subscriptions required. FloProtect is an optional monthly plan that extends the one-year warranty to five years and adds a water-damage deductible guarantee of up to $5,000.

Verified specs

Every figure below comes from Moen's product page, the Flo product specification sheet or installation sheet INS11955. Where Moen does not publish a number (maximum flow rate, for instance), we leave it out rather than borrow one from a retailer.

Additional figures from the installation sheet that the table does not carry: maximum continuous pressure 125 psi with 80 psi or lower recommended (a pressure-reducing valve upstream if you are above that); ambient temperature 32°F to 140°F for the device and its power supply; power supply 100 to 240 VAC on a 10-ft cord, with 25-ft low-voltage extension kits (part 920-003) that chain up to four deep; Wi-Fi 2.4 GHz, 802.11 b/g/n only; minimum clearances for the 3/4-in. and 1-in. bodies of 6 in. above, 3 in. at the sides and bottom, 4 in. of straight pipe on the inlet and 2 in. on the outlet.

Where it shines

It detects leaks the way losses actually happen. On the water losses we worked, the expensive ones were rarely dramatic: a supply line that let go while the family was at work, a toilet fill valve stuck open in an empty house, a pinhole in a copper line weeping into a wall cavity for months. A floor sensor catches the first one if it happens to be under that sink. The Flo catches all three from one point on the main, because it reads flow that never stops and pressure that will not hold. Moen's drop-per-minute claim is a manufacturer figure we cannot test, but the mechanism behind it, a closed-valve pressure-decay test run daily, is how a plumber finds a hidden leak with a gauge.

Shutoff is automatic and free. Once Learning Mode ends, the device closes the valve on its own when FloSense sees abnormal use and you have not answered the alert. That is what limits a loss when nobody is home, and it does not sit behind a paywall.

Alerts reach you several ways. Push, text, phone call and email. A phone call wakes a household at 3 a.m.; a push notification often does not. The app also reports flow rate, pressure and usage history.

Freeze and point-sensor coverage. The temperature sensor warns of near-freezing conditions at the main, and Moen's Smart Water Detectors pair with the valve so a wet pan under the water heater closes the main too. Our sensor placement guide covers where those pucks go.

Insurers know it. Farmers names the Flo on its leak-detection page and Moen puts an insurance verification letter in the app. Our insurer discount table lists the programs we could verify. It also integrates with Alexa, Google Home, Ring, Alarm.com and NICE.

Where it falls short

The learning period. Moen's help center says Learning Mode typically lasts 14 days with normal water use and can run to 28; a second Moen page puts it at approximately 28 days. During that window you get no water-related alerts, usage-based automatic shutoff does not occur, and the mode cannot be skipped. Shutoff triggered by a paired Moen detector still works, and you can still close the valve from the app. Install it when the house is occupied and used normally; a device installed the week before a long vacation protects nothing on that trip.

One-year warranty without the plan. FloProtect extends the base warranty to five years and adds the deductible guarantee, but it is a recurring charge for coverage that Phyn includes for two years at no cost. For a valve body that will sit in a pressurized supply line for a decade, one year is short, and we score it accordingly.

No battery, and it needs the internet. With the power out the valve stays where it was. With power but no internet, Moen's instructions say the device enters Local Mode and may shut off water frequently, which is the fail-safe direction but a nuisance. A small UPS at the main covers the device and the router through short outages.

Outlet and Wi-Fi at the main. The outlet must be within 10 ft unless you buy extension kits, and the network has to be 2.4 GHz with a usable signal where the main enters the house, usually a basement corner or utility closet. Check signal with a phone at that spot before anyone picks up a torch.

Install restrictions. No galvanized pipe upstream, no soldering with the device in the line, no thread sealant on the union nuts, adapters not included. None of these is a flaw, but each one can stop an install on the day.

Installation notes

Moen recommends a licensed plumber, and we agree; the main is cut and the device goes in with unions. What we would tell that plumber, from Moen's installation sheet:

1. Location. On the accessible cold-water main, above ground, after the meter, the main shutoff and the pressure-reducing valve, before the water heater and softener, and after any branch feeding irrigation. Never on a fire-sprinkler line. Horizontal or vertical is fine; the arrow points toward the house.
2. Clearances. For the 3/4-in. and 1-in. bodies: 6 in. above, 3 in. at the sides and bottom, 4 in. of straight pipe before the inlet and 2 in. after the outlet. The 1-1/4-in. body needs 8 in. above and 7-1/2 in. of straight inlet pipe.
3. Pressure. 125 psi maximum continuous, 80 psi or lower recommended. If a gauge on a hose bib reads above 80, fix the PRV first.
4. Pipe material. No galvanized steel upstream. Finish all soldering before the device goes in, lubricate the O-rings, no thread sealant on the spacers or union nuts, and leave the spacer in place until the device is ready to be powered up.
5. Power and network. A receptacle within 10 ft (GFCI recommended), the power supply mounted off the floor, and a 2.4 GHz network with a solid signal at the main. Outdoors, Moen wants a weatherproof receptacle enclosure at least 12 in. above grade and no exposure below 32°F or above 140°F.
6. After power-up. Expect two to four weeks of Learning Mode with no usage-based alerts or shutoffs. Pair any Moen detectors right away, since detector-triggered shutoff works during learning.

Know your manual shutoff too; our how to shut off water to the house guide walks through it.

Alternatives

Phyn Plus (2nd Gen). The other inline monitor we recommend: an ultrasonic flow sensor plus pressure-wave analysis, a Plumbing Check for pinholes, a two-year warranty and no subscription of any kind. It ships with 1-in. NPSM threads and needs adapters for other mains, and it also has no battery. Our Moen Flo vs Phyn Plus comparison goes line by line; our Phyn Plus review covers it on its own.

YoLink Smart Water Valve Controller. For a homeowner who will not cut the main: it clamps onto the existing quarter-turn ball valve, runs on batteries, and closes the valve when a YoLink leak sensor gets wet, even with the power and internet down. It does not watch flow or pressure, so it only knows about leaks a sensor can touch.

Flume 2. Not a shutoff: a strap-on meter reader that gives flow alerts without plumbing work. The right first step for a renter or a condo.

All four are compared in the best smart water shutoff valve roundup; point sensors to pair with any of them are in the best water leak detector guide.