How to Winterize Your Plumbing

When you are going to be away from home for an extended time during the winter be careful about how much you lower the heat. That strategy makes a lot of sense in terms of energy savings but can be disastrous if a cold spell causes a pipe that would normally be protected freezes and bursts.

If turning off the heat is your preference, then the best way to protect the pipes is to drain the water system. With no water in the system, freezing is not a problem. It’s always a good idea to create a checklist when draining the water system, to be sure that no step is forgotten.

Tools Needed

A garden hose to drain the hot water heater.
A shutoff key tool (to turn off the valve at the street).

Draining the Plumbing System

Close the water supply at the street using the shut off key tool. Open the sliding cover at the water supply curb box and locate the valve inside. This will look like a hexagonal nut. The key tool end will fit right over it. Turn the tool using the horizontal handle. It may take some force to turn it, but don't overdo it! Some valves, particularly older valves, are also a little touchy about what position they need to be in to completely cut off the water. You may have to play with valves like that to find the exact spot where the water is completely shut off.
After the curb valve has been closed, close the main shut-off valve inside the house. This valve should be fitted with a small drain cock (rather than a knob). Do not open this again until all the water has been drained from the system.
Drain the hot water system.
Drain the cold water system.

Drain the Hot Water System

The first thing to drain in the hot water system is the water heater itself. You must turn it off before draining it. If it's an electric water heater, you will need to flip the water heater breaker in the power panel. If it's a gas water heater, there should be a "pilot" temperature setting on the heater. Failing to turn the water heater off before draining it will cause it to fail.

Inside your house, open the hot-water faucet in a sink or tub. This will prevent a vacuum from forming in the lines and preventing the heater from draining. Go back to the water-heater, attatch a garden hose to the water heater drain valve, and open the drain valve to drain the hot water out of the tank. Make sure the far end of the hose is draining somewhere that won't be harmed by hot water. A driveway is ideal. Finally, open all faucets. This will drain the water out of the pipes to the level of the lowest fixture.

Drain the Cold Water System

With the hot water system drained, move on to the cold water supply. If the shut-off valve inside the house is a drain cock, the system is easily drained. Open all the faucets and let them drain until the water stops flowing.

Remember that water in a perfectly horizontal pipe will not completely drain, nor will water flow uphill without pressure behind it or suction in front of it. So to drain the system completely dry you will have to disconnect a section of pipe and force water out of the line with air pressure on both hot and cold water lines. If you have a summer house and need to completely drain the system for winter it’s a good idea to install a utility faucet at the lowest level to allow water to drain without having to take pipes apart. You’ll have to use buckets or a hose depending on how the system is designed.

Turning Water Back On

When the time comes to turn the water back on, refer to your checklist again.

Close all the branch valves and open the main inside valve and then the curb valve. You should open at least one faucet's hot and cold valves open if they wereclosed after winterization.
If the system appears to be in good condition, open one branch valve at a time.
Now you can start opening the other branch lines that feed various faucets in your home. Make sure that each branch line is in good working order before opening another valve.
Expect some air escape from faucets until the system is full and flowing. This can be noisy and you might see some sediment escape at first.
Open the valve to fill the hot water tank. After the tank has filled with water, turn the power-supply to the water heater back on at the breaker box (or the thermostat). Once the water temperature has been brought back up, test the pressure-relief valve according to the manufacturer's instructions. This safety device is designed to prevent excess pressure build-up or overheating inside the tank. If it's faulty, you may need to have it replaced by a licensed plumber.

Credits and Suggested Reading:
University of Illinois, Building Research Council: An Investigation into Freezing and Bursting Water Pipes in Residential Construction Crawl Spaces in the Home

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