Don’t Use That Valve! - Know This Before Shutting Off The Water

There will actually be two main shut off valves at the typical suburban residence. One valve will be at the city water meter (usually located in a buried box near the street). This city valve is usually under a locked lid, but with commonly available tools it can be accessed and shut off in the event of an emergency.

This will shut off the water to the entire property – including any yard sprinkler system and fire suppression system. Although, some larger properties have a separate meter for the irrigation system.

By plumbing code, a main shut off valve is also required near where the main water supply comes into the house. This is the valve designed for the homeowner to use and have easy access to. By shutting off this valve, just the house water system will be turned off – not the separate irrigation system or conventional fire suppression system.

Most commonly in our area, this valve is located in the front flower bed where the water supply pipe (which is buried in the yard) goes underneath the slab foundation to the first “manifold”. Or, in newer homes, the main shut off valve may be located behind a wall panel in the garage or in a utility room.

In areas with higher pressure, a special valve called PRV (Pressure Reducing Valve) is installed next to the main shut off valve.

Know where this valve is, make sure it is in good working condition, and have all occupants of the home practice shutting off the water in the event of a plumbing emergency to prevent damage to the home. This valve will either be a lever-handle ball valve or a round-handle gate valve (more on these later). 

A shut off valve is required, by plumbing code, to be installed on the cold water supply pipe to the water heater (the top right-hand side when facing the water heater). Since this valve supplies water to the water heater, by shutting it off you will also be shutting off the water to all of the hot water pipes throughout the rest of the home.

This valve will also either be a ball valve or a gate valve. Typical practice in our area is for this valve to connect to a flexible supply pipe that attaches to the inlet pipe on top of the water heater.

Because the typical water heater has an average life-expectancy of about 10-12 years in our area, many people opt to install some sort of automatic shut off valve as well. This valve has a sensor which detects water if there is a leak and automatically turns the water off.

Another type of shut off valve that it is important to be aware of is the PEX manifold system.

Most newer homes (2010+) are plumbed with a type of flexible plastic pipe called PEX. One of the ways this piping is installed is by running a bunch of smaller pipes to the fixtures throughout the home from a single point called a manifold. Think about it like an electrical breaker panel for your water system. At this one central point there are a bunch of smaller shut off valves that you can operate to shut off the water to every bathroom/fixture in the house.

These can be a little touchy when they haven’t been used for a long time. Their all-plastic and o-ring construction doesn’t corrode, but o-rings have a tendency to become stiff and leaky over time. If these individual valves start to leak, they can often be rebuilt with new replacement parts from the manufacturer. The most common one in use around here is manufactured by Viega.

For typical residential toilets, there will just be one shut off valve for the cold water pipe supplying the toilet with water.

Typical practice for the “rough-in” dimensions is to locate this valve about 6” to the left of the centerline of the toilet (when facing the wall). It will come out of the wall about 6”-8” inches off of the floor.

This valve will either be a quarter-turn “stop” or a multi-turn “stop”. More about the differences between these two valve styles later.

Every bathroom sink will have two shut off valves – one for the hot water, one for the cold. You’ll see these small shut off valves right where the water pipes come out of the wall inside the sink cabinets.

These valves will connect to the underside of the faucet with flexible supply lines. These days, the supply lines are made out of rubber with a braided steel reinforcing sheath. Older valves often used ⅜” soft copper as the supply lines. These copper tubes were connected to the valves either with a compression nut and ferrule or soldered directly to the valves.

The “rough-in” dimensions vary quite a bit from one faucet to the next. But as a general rule, the hot valve will be 4”-6” to the left of the drain pipe, and the cold valve will be 4”-6” to the right of the drain pipe when facing the wall. Both of these valves will be slightly above or slightly below the drain pipe.

Under kitchen sinks, there will typically be three shut off valves. The two uppermost valves will be the hot and cold valves for the sink faucet. The lower valve is for the dishwasher.

Conventionally, these valves would connect to the faucet in the same way as bathroom valves/faucets with replaceable supply lines. Many newer kitchen faucets now come with integrated supply lines that connect directly to the ⅜” outlet of the valves.

In larger, newer homes, you may find an additional valve designed to feed an under-sink water filter or instant hot water tap.

The common rough-in dimensions are very similar to bathroom faucets with the hot valve ideally being on the left side of the drain pipe when facing the wall and the cold valve being on the right side. Of course, there is usually much more space under the kitchen sink, so you will often see these valves in various places.

The third and lowest valve under the kitchen sink is typically a hot water valve for the dishwasher located to either the right or left hand side of the kitchen cabinet.

You will frequently find this valve directly below the hot valve for the kitchen sink faucet. The supply line that connects to it (either ⅜” soft copper or braided steel sheathed rubber) will run horizontally along the bottom of the cabinet and go behind the dishwasher through a hole in the side of the cabinet.

If your refrigerator has an ice maker or filtered water spigot, then it will typically be supplied by a cold water shut off valve behind the refrigerator. This valve is traditionally located in a recessed, open-front plastic box.

When the valves have to be replaced, sometimes it can be done inside the box itself. Other times, some of the drywall directly below the valve has to be removed to access the pipe lower down.

In some larger homes with built-in refrigerators (like some of the Sub-Zero models), the shut off valve may be located in an adjacent cabinet or underneath the kitchen sink due to the refrigerator being too large to readily move by hand.

The clothes washing machine hot and cold water supply valves are typically located in a recessed box directly behind the washer. This box, commonly called a “washer box” also contains the indirect waste drain pipe for the washer’s wastewater discharge hose.

Some of these valves screw into threaded adapters that are located in the box itself. This means that the valves can be replaced without having to remove any sheetrock. Many of the newer boxes have valves that connect to the pipe below the box. This means that replacement required the removal of some sheetrock below the box.

The older style valves were multi-turn angle valves that shut off with a rubber washer. Newer style valves have a little lever handle that operates a ball-style valve instead.

Outdoor hose faucets typically won’t have a separate shut off valve just for them. They are screwed directly into a threaded fitting that is attached to the pipe in the wall. This means the water must be shut off to the house in order to make repairs or replace these faucets.

Newer hose faucets are called “frostproof faucets” because they are long in design and shut off back inside the wall where it is less likely to freeze. Older hose faucets would almost be identical to washing machine multi-turn valves and would operate with an internal rubber washer.

There is one interesting quirk/feature about common construction practices in this area. If there is a hose faucet located close to the main water shut off valve in the front flower bed, there may be a separate, smaller valve in the “water box” that controls just this hose faucet.

Like outdoor hose faucets, shower and tub valves generally have all of the plumbing hidden inside the wall.

Unless there is an access panel in the wall, there is typically no way to shut off the water for just these fixtures. In order to perform repairs like replacing the cartridge, the water will need to be shut off for the entire house. There is an exception to this, though.

Many of the newer shower valve designs do have built-in shut off valves for service. You can check for these by removing the handle and decorative trim plate to expose the valve body in the wall. If there are integral “stops”, then they will look like small slots on either side of the valve that can be turned with a flat-bladed screwdriver.