Any talk of a home water main can be enough to send some homeowners into a tailspin. Where is it located? What size is it? How does it work? Should I call the plumber for this? Your water main is never far from your home and should be fairly easy to find, but regardless of whether you are interested in installing the Flo by Moen Smart Water Shutoff, it’s always better to know where the main is before leaks occur.

The Smart Water Shutoff will be installed on the main water supply line (water main) coming into the home, downstream of (after) the main shutoff valve (it is not intended to replace the existing shutoff valve). To find the appropriate Smart Water Shutoff size for your home, you'll need to know the size of your home’s main line. Watch the video below and read further in this article to learn how to find the main water supply line in your home and its size.

The size may be clearly marked on one side of the main shutoff valve or on one side of the pressure reducing valve (if your home has one). If the size is not stamped on either the main shutoff valve or the pressure reducing valve (if your home has one), you can also measure the circumference of the main water supply line. Circumference is the distance it takes to go around the pipe once. If you have a cloth tape measure, wrap the tape around the pipe once and measure to the nearest 1/8 of an inch. Alternatively, you can wrap a string (or paper) around the pipe once, mark the length, and lay it flat on a ruler to measure the length.

A PRV is ideal for most residential plumbing applications because it balances out the erroneous pressure dips and spikes to provide a more smooth and stable supply of pressure to the home at all times. It basically helps to preserve the entire plumbing system and its connected appliances. A PRV also allows the homeowner to fine tune the water supply pressure coming into the home and, with a Flo by Moen Smart Water Shutoff installed, you can adjust your own home's supply pressure easily using the real-time telemetry data in the Flo by Moen App. When installed, the Smart Water Shutoff should be downstream (after) the PRV.

In this section, we’ll explain common places in residential homes where the main water shutoff valve is located. Every home is different and the location of the valve may vary based on climate, but here’s how to find your water main and how to use them. And if you already know where your water meter is, the shut-off valve is never far off!

In colder climates, the main water shutoff valve is usually located in a warm area indoors to prevent freezing pipes. Check your basement, garage, crawl spaces, and water boilers for the largest pipe protruding through the ground or wall. Follow the pipe and you’ll find the shut-off valve.

Laws prohibit the installation of any device that can limit or prevent water flow from entering the fire suppression system. For homes where there is a fire suppression system, there will also be a shutoff after the fire suppression line splits. The Flo by Moen Smart Water Shutoff size should reflect the size of the plumbing AFTER the fire suppression system splits, and after the home's main water shutoff valve .

In warmer climates where there’s less risk of freezing pipes, the water main usually enters the house from the street level. The main water shutoff valve can likely be found outside of the home and accessed either above or below ground.

Above ground, attached to an exterior wall of the house.

Below ground, in the utility box (curbside) in front of the house.

At the ground level, there are circular or rectangular (with rounded edges) plates made of plastic or metal. The face of the plate may read, “WATER”. This plate is the lid to a utility box, typically 2 ft x 2 ft (circular plates may be slightly smaller). Lift the lid off of the box to find the main water shutoff valve (next to the water meter).

Note: The Flo by Moen Smart Water Shutoff is outdoor-rated for rain and irrigation, but it cannot be submerged or burried. It must be installed above ground to prevent flood/excess moisture damage to the unit.

The main water shutoff valve sits on the main water supply line, where water enters your home (residential) from the municipal water line (city). The main water shutoff valve is how you can turn your home’s water on and off and some types allow for controlling the flow amount. There isn’t a huge distinction between valve types, but there are different types of valves.

Here are some common ones:

Ball valve

Ball valves are typically seen in newer homes. They don’t regulate the amount of water flow but have lever handles to turn the water on or off. They’re easy to use and only require a short quarter-turn of the handle. These can be installed either horizontally or vertically on the main water supply line. Generally, the valve can either be fully opened or fully closed with a quarter turn of the lever.
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Gate valves are often seen in older homes and, similar to ball valves, only operate “on” or “off”. You might have to turn the wheel clockwise for a bit to turn off the water supply completely.
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Globe valves look similar to gate valves, but, unlike ball valves and gate valves, they can regulate the amount of water flow. Turn them clockwise to turn off the water supply.

​Send us a photo!

If you are unable to determine the size of your main water supply line using the Flo by Moen size guide, please send a picture to our Support Team at support@meetflo.com.