Water Valves
 

In a municipal water system, the source of water is the water main that runs beneath the street. A corporation stop is located at the tap-in; it is usually made of brass and is installed using a special tool that doesn't require shutting off the water supply.
 

A second valve, the curb stop, is located at the property line; it controls the flow of water to the residence. The curb stop is similar to the corporation stop, but it is used to shut off the water for repairs, nonpayment of water bills, or flooded basements. Since the corporation stop is usually inaccessible, the curb stop is used as the isolation valve. The curb stop is in an access box, and a long-handled wrench or "key" is used to reach the valve.
 

In a typical installation, the water line then leads to a pit where the meter is installed. (In older homes, the meter may be located inside the house.) A meter stop is mounted on the street side of the water meter to isolate the meter for maintenance. Some locales call for a gate valve to be installed on the house side of the meter to shut off water for repairs. The curb and meter stops are not intended to be used frequently and can fail if used too often.
 

The water line then leads underground to where it enters the house. Two valves are usually installed at that point. First is the main shut-off valve, probably a gate valve or a ball valve, and next the pressure-reducing valve, which regulates the water pressure to the rest of the house.
 

The line then usually leads to the water heater, where it splits, one branch continuing as the cold water line and the other supplying the heater, but first it passes through a stop valve, which can shut off the water for maintenance. At the bottom of the heater is a boiler drain, which can be used to drain the heater. At the top of the heater is a pressure-relief valve.
 

If the laundry tub is located nearby, boiler drains may also be installed there to connect to the washer hoses. (If a washing machine box is used, a variety of valves may be used.) One or more pipes lead to the outside of the house where a hose bib or a sillcock will be found. These may be freezeless types.
 

Each fixture will have a supply stop where the supply tube connects to the water line. This allows for the repair or removal of the fixture without shutting off the water to the whole house. And each fixture will have some type of valve as well. Sinks and lavs will have faucets. Tubs and whirlpools will have control valves, as will showers. Toilets will have flush valves.
 

If the refrigerator has an icemaker, or if there is a hot water dispenser installed, there will be a saddle valve mounted on the cold water line nearby.
 

If a sump pump is installed, it will discharge through a check valve to prevent the discharged water from leaking back into the sump.
 

It should be remembered that any valve that allows for a discharge of water creates a potential risk of backflow into
the municipal water supply.
 

Vacuum breakers are required by most codes for dishwashers,
for water softeners, and for any faucet to which a hose
may be connected.
 

Without a vacuum breaker, there is always a chance (however slim) of siphoning contaminants into your drinking water system.
 

Types of Water Valves
 

    Ball Valves
    Check Valve
    Gate Valves
    Build-In Valve
    Floating Valves
    Angle Valves

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