How to Drain Your Home’s Plumbing System

Although not a common task, draining your home’s plumbing pipes is occasionally necessary. Some common reasons for doing this include fixing a water hammer problem, shutting down a seasonal property for the winter, or making major plumbing repairs, such as replacing or extending the main plumbing lines. Fortunately, though draining a home’s plumbing pipes might seem like a daunting task, it’s actually very easy. Let’s take a closer look at the reasons you might want to do this.

Water Hammer

A water hammer (also called hydraulic shock) is a situation in which plumbing pipes bang loudly when faucets are turned on and off or when an appliance suddenly starts or stops the flow of water. The problem occurs because of air in the plumbing lines, which allows the water to oscillate back and forth and bang the pipes against one another or against the wood framing. Even if your system has air chambers to absorb this shock, too much air trapped in the system will make the problem persist. The answer is to drain the system and refill it, so the air gaps are confined to the designated air chambers.

Seasonal Shutdown

Draining the plumbing pipes is one of many items on a winter preparation checklist. These are especially important when a property in a cold climate will be left unattended for the winter. Frozen pipes that burst can fill an empty home with thousands of gallons of water and cause many thousands of dollars in damages. 

Major Plumbing Repairs

Although draining the entire system is not part of every major repair or addition to the home plumbing system, it can sometimes be necessary, such as when a basement bathroom is being installed and the plumbing pipes lying above the installation need to be drained when the new pipes are connected to the existing system. There can be a substantial amount of water in the supply pipes within the home. And at the moment the pipes are cut to connect the new supply pipes, this water can flow out unless they have first been drained. 

Draining your home’s water supply pipes, and refilling them when the work is done, is a very easy process. 

What You’ll Need

Equipment / Tools

• Tubs and faucets

Materials

• Cloth or plastic wrap (optional)

Instructions

1. Shut Off the Water ValveShut off the main water valve at the water meter.
2. Open the Sink FaucetsStarting at the top floor, open all the sink faucets. This will allow air into the system, which will help the flow of water as you drain the system. 
3. Open the Faucet in the Laundry TubGo to the basement or the lowest level in your home, and open the faucet in your laundry tub or lowest sink. Let all the water from the above floors drain out.
4. Open the Tub or Shower FaucetsNow, open all the tub or shower faucets.
5. Flush All ToiletsFlush all the toilets, emptying the tanks.
6. Leave the Faucets in the Open PositionIf you are leaving the property unattended (such as when leaving a vacation home for the winter), leave the faucets in an open position. There should be no water coming out of any faucets, except a possible slight residual drip from the lowest faucet as any remaining water in the pipes dribbles out.

Tip

When a home is left unattended for a long period, standing water in toilets, sink traps, tub drain traps, and floor drains can evaporate, removing the drain seal that keeps sewer gases from rising up into the home. Some experts recommend blocking drains and toilet bowls with wadded-up cloths or plastic wrap to keep the sewer system sealed off from the house during long absences.  If you are winterizing, it is imperative that you soak up all the water from toilets, toilet tanks, traps, and anywhere where you would have standing water. When water freezes it expands. This can crack porcelain fixtures, traps, or appliance fittings. If the house is heated to a minimum this may not be required. If the heat will be turned off, you may additionally have to wrap the incoming water service with heat trace & insulation.

How to Charge the Pipes With Water

Reversing the water flow and filling all the pipes up again is an easy matter of reversing what you did to drain the pipes.

1. Close the Basement FaucetClose the basement faucet or lowest level faucet in the house.
2. Close the Upper FaucetsNow close all the upper faucets. Closing the faucets allows air to remain in the pipes to recharge the air chambers you may have in your home’s plumbing system.TipIt is good practice to close all faucets except the lowest level, for example, the laundry faucet in this case. When you open or re-energize the system it is good practice to open the main valve slowly & only half way. When you get a steady flow of water from the laundry faucet, close it and listen for the system to fill & become fully pressurized. This can be done by listening to water flow. When the flow is no longer heard you can then fully open the valve. If it is a gate valve (round handle), when you get fully opened back off a 1/4 turn. The reason for this is that old valves under pressure can fail when re-energizing. Backing off on the valve will help to keep the valve from freezing (getting stuck) for future use.
3. Open the Main Water ValveOpen the main water valve to let the water back into your pipes.
4. Turn on the FaucetsOne by one, starting with the highest level faucets, turn on the faucets and let the air/water sputter out until only clear water flows from the faucet. You may see discolored water come out at first, but this is normal.
5. Open Other FaucetsOpen the shower faucets to let water back into those pipes.
6. Flush the ToiletsFlush the toilets to refill the tanks. 
7. Turn off the FaucetsOnce the water is running clear, turn off the faucets. Start at the highest floor level and work your way down through the house. You may have an occasional sputter the next time you use a faucet, but the pipes will quickly purge any remaining air.