How to Drain Your Home's Plumbing System

By
Bob Formisano
Bob Formisano
Bob Formisano is a licensed architect and builder with nearly 40 years of experience building new homes and restoring older homes. One of his specialties is repairing old systems dating back to the 1920s, including galvanized water pipes, knob-and-tube wiring, and more. His home repair articles for The Spruce span more than 10 years.
Learn more about The Spruce's Editorial Process
Updated on 06/02/22
Reviewed by
Richard Epstein
Richard Epstein
Reviewed by Richard Epstein
Richard Epstein is a licensed master plumber with over 40 years experience in residential and commercial plumbing. He specializes in estimating as well as design and engineering for plumbing systems, and he works for one of New York's largest union plumbing construction companies.
Learn more about The Spruce's Review Board
How to Drain Your Home's Plumbing System

The Spruce / Adriana Sanchez

Project Overview
  • Working Time: 20 - 30 mins
  • Total Time: 20 - 30 mins
  • Skill Level: Beginner

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. 

Featured Video

What You'll Need

Equipment / Tools

  • Tubs and faucets

Materials

  • Cloth or plastic wrap (optional)

Instructions

  1. Shut Off the Water Valve

    Shut off the main water valve at the water meter.

  2. Open the Sink Faucets

    Starting 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 Tub

    Go 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 Faucets

    Now, open all the tub or shower faucets.

  5. Flush All Toilets

    Flush all the toilets, emptying the tanks.

  6. Leave the Faucets in the Open Position

    If 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 Faucet

    Close the basement faucet or lowest level faucet in the house.

  2. Close the Upper Faucets

    Now 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.

    Tip

    It 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 Valve

    Open the main water valve to let the water back into your pipes.

  4. Turn on the Faucets

    One 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 Faucets

    Open the shower faucets to let water back into those pipes.

  6. Flush the Toilets

    Flush the toilets to refill the tanks. 

  7. Turn off the Faucets

    Once 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.