Pouring RV antifreeze into drain to prevent trap from freezing.
Preventing Frozen & Burst Pipes:

The Plumbing System
So The Heat Can Be Turned Off

In This Article:
  • The water supply is shut off.
  • Water heater is drained while faucets are opened.
  • Fixtures and appliances are drained.
  • Using compressed air may be necessary.
  • RV antifreeze is added to all drain traps to prevent damage from freezing.
  • The furnace can hold water too.
  • Special requirements for well systems.
Related Articles:
Skill Level: 2 (Basic) Time Taken: About 2 Hours

By , Editor


Recently a friend asked me to winterize her house. She wanted to move closer to town, so she put her house up for sale. Here in Northern Michigan it's normal for houses to sell slowly in the middle of winter, but with our current housing market troubles there are even fewer potential buyers. To save money, she needed to turn off the heat for the rest of the winter.

In a cold winter climate like Michigan, you can't just leave a house or cottage all winter with no heat... the pipes will freeze and possibly burst. So we had to drain the water supply pipes and prevent the water in the drain traps from freezing.

If the temperature inside a house gets below 32 degrees Fahrenheit (0° Celsius) it's likely that the water supply pipes and the drain traps will freeze.

When water freezes it expands 9 percent, and if there is no room for expansion it's possible that the pipe will burst. When the ice thaws the pipe will leak, and in the supply system this leak could occur anywhere. Fixing a burst pipe can be expensive, but the damage from uncontrolled water leakage can easily reach into the thousands of dollars. Believe me, you do not want to experience the hassle and expense of having a pipe burst and spraying water all over your basement, or anywhere in your home.

A properly-insulated house built to current building codes will probably never experience this problem under normal conditions. What do I mean by normal conditions? The heating system runs properly, the electricity supply stays on, and the furnace fuel supply never runs out.


Basic Procedure For Draining Supply Pipes:

  1. Shut off the water supply.

  2. Open one or more faucets at the highest point in the system.

  3. Open a faucet or drain valve at the lowest point in the system.

Since this house had municipal water service, there was a pipe entering the basement with a water meter just above the entry point.

Note that there are red handles above and below the water meter. This is done so the water meter can be removed for service and the pipes do not need to be drained.


Step 1: Shut Off The Water

I turned off both valves. These are ball valves, which only require a quarter turn. Shutting off water supply.


Step 2: Let Air Into The System

Then I went upstairs and turned on the kitchen faucet. No water came out.

When I'm draining a water supply system, I always open the faucet at the highest point in the house, such as a second-floor bathroom. Since this was a one-story house, the kitchen faucet was the highest point in the system.


Step 3: Open A Valve At The Lowest Point

Water heater is often the lowest point in system. The water heater (in the basement) was the lowest point in the water supply system, so the water heater drain was the logical point to drain the water out.

This was a 38 gallon water heater, which is typical for a smaller house like this that has only one bathroom.


I turned off the water heater's gas supply by turning the gas valve to "OFF".

The off position is reached when the OFF marking is aligned with the metal tab in molded into the front of the valve body (green arrow). That large red button to the left of the valve dial may need to be pressed down or lifted up in order for the dial to be turned past the PILOT position. This button is designed to prevent the dial from turning directly from OFF to ON without first stopping at the PILOT position.

Shutting off gas supply to the water heater.


Water heater drain valve.

Water Heater Drain Valve:

This water heater drain valve doesn't have a normal handle... it had a short stem with a screwdriver slot (red arrow).

Many water heaters have a plastic drain valve with a normal handle.


I placed a small plastic bucket under the drain valve and opened the drain valve with a large flat-blade screwdriver.

Since I had opened up a faucet upstairs, the water flowed out vigorously.

Opening a faucet is important. If there was no opening to let air into the supply pipes, the water will drain slowly or flow out in surges followed by moments of trickling flow. Gurgling sounds will be heard as air tries to enter the system from the drain opening. And it will take f-o-r-e-v-e-r to drain the system.

Emptying the plumbing system via the water heater drain valve.

I let the water drain from the water heater until the bucket was nearly filled. Then I shut off the drain valve and carried the bucket upstairs and dumped the water down the toilet.

(Actually, I poured the water from this pail into a larger pail, started draining water again, and carried the larger pail upstairs. I brought two pails but the larger one didn't fit under the drain valve, so I couldn't just swap them while the water continued to drain.)

This smaller container must have been a 2-gallon pail, because I think I made about 19 trips. It took about 45 minutes for all the water to drain out. My advice: Use two pails that will fit under the drain valve.

Note About Electric Water Heaters:

Since gas water heaters have a burner beneath the water tank, the bottom of the tank (and therefore the drain valve) is usually about a foot above the floor. But... electric water heaters often have a drain valve that is very close to the bottom of the appliance, and since most plumbers install a water heater directly on the floor, the drain valve on an electric heater may be very close to the floor. This is a real pain-in-the-@ss to drain. I  usually connect a short piece of garden hose to the water heater drain valve and place the hose in a bucket. When water will no longer flow from the hose into a bucket I will place the end of the hose in something shallow, such as a dishpan or even a cake pan.


Walk Out Basements: If a house had a "walk-out" basement, then a garden hose could be connected to the water heater drain valve. The hose can be run out the door and the system will drain itself with minimal effort.

Pumping: I have used a cheap drill-powered pump (that connects to a couple of garden hoses) to push the water up and out of a basement window. It worked okay, but the pump leaked and sprayed a couple of gallons of water all over the basement.


Gravity Makes It Easy:

Draining the water in this house was easy because while standing in the basement I could see all of the horizontal plumbing runs. I traced the copper pipes from the water heater and wherever the lines turned vertical, they went up, never down. I could tell that all of the water would drain simply by opening the water heater drain. Good plumbing, but not all houses are so lucky. Often the pipes will turn down and then up, leaving a "trap" or "valley" that won't drain by gravity. To fully drain those pipes compressed air is the logical solution.

Forcing Out Water With Compressed Air:

If the plumbing can't be drained by gravity, then an air compressor can be used to blow the water from the supply pipes. The trick is getting air into the pipes.

Washing machine connections and outdoor faucets are the easiest because a garden hose can adapted to an air hose.

A kitchen or bath faucet isn't as easy. Perhaps the simplest way to force compressed air into these faucets is to remove the aerator and insert a simple blow gun, wrapping a rag around the nozzle to seal the connection.


Letting More Air Into The System:

Letting air into the pipes by opening the sillcock. When the water flow had slowed to a trickle, I went outside and opened up the outdoor faucet.


Then I set the clothes washer control to the beginning of a normal wash cycle and started it. No water came out (as expected) and I could hear a low hum from the solenoid-operated fill valves being held open.

I stopped the cycle after a few seconds.


Loosening a water meter fitting to drain a short section of vertical pipe. There was one minor problem area: the vertical pipe just above the water meter. With no opening to drain this short section of pipe, I used a large wrench to loosed one of the threaded fittings on the water meter.



In Hindsight...

I didn't think of this until later... there may have been a bleeder valve on one of those ball valves used to shut off the main incoming water line.

This picture shows a "Stop and Waste" ball valve.

This is different from a regular ball valve because it has a cap that covers a small opening. When the water is shut off, this cap can be unscrewed so the water downstream of the valve can be drained.

This valve is supposed to be installed with the bleeder downstream of the ball valve, otherwise it's useless.

Bleeder cap on a "stop and waste" ball valve.


Other Details:

Disconnecting washing machine hoses to drain the water. Since the washing machine water supply hoses ran down behind the appliance, they formed a trap. Unless forced out or drained out by gravity, water will stay in these hoses.

I removed the washing machine supply hoses (I needed a pair of Channel-Lock pliers to loosen the fittings) and drained each hose into a cup.


Even though I had already flushed the toilet once, the tank was still about half full.

These newer 1.6 gallon per flush toilets have the same size tanks as older units; the only change is that the flush valve closes sooner, thereby letting less water into the bowl.


To drain the remaining water from the toilet tank, I flushed again and held the flush lever down until the water level reached its lowest possible point.


There was still about ¼ inch of water left in the tank. I suppose I could remove this water with a sponge, some towels, or a turkey baster, but I didn't have any supplies because this house was vacant. Slight amount of water remaining in toilet tank after flushing.


Adding RV Antifreeze:

Adding RV antifreeze to toilet tank to prevent freeze damage. To prevent this small amount of water from freezing, I poured about a cup of RV antifreeze into the toilet tank.

Even if this water froze, it's unlikely to cause any damage because when the ice forms it would have room to expand.


I used a plunger to remove some of the water from the toilet bowl. Using a plunger to push water from the toilet bowl.


Pouring RV antifreeze into the toilet bowl. Then I poured about a quart of RV antifreeze into the bowl. It's important to make sure the liquid covers the opening, or else sewer gases could enter the building.


I poured about two cups of RV antifreeze into each sink drain. Pouring RV antifreeze into the sink drain to fill the trap.


Adding RV antifreeze to tub drain trap. I poured a similar amount into the bath tub drain.

I wiped up the excess antifreeze around the drain, just in case. I can't imagine how ethylene glycol and propylene glycol could damage any plumbing fixtures... but I didn't want to take chances with this tuff leaving a pink stain. Maybe I'm just paranoid.


I poured antifreeze into the kitchen sink. Antifreeze for the kitchen sink drain trap.

The point here is to try to replace the water in the sink trap with antifreeze... but the antifreeze won't displace the water, it will mix and displace some of the water. The only way to ensure that the antifreeze has its maximum protection (i.e. -50 degree freezing point) is to remove all of the water before adding antifreeze. I doubt that this house will get anywhere near that temperature, given that the coldest winter temperatures around here are about -20° F, and the house is sure to stay much warmer than that. I would be surprised if the temperature inside this house ever got below 10 degrees... but I'm certain that the temperature will get below freezing.


But Wait... Appliances Hold Water Too:

Putting RV antifreeze in the dishwasher to protect the pump from freeze damage. You may not see any water, but normally a dishwasher holds some water below below it's drain.

Underneath this point there is (normally) a pump that has water in it all the time. I poured about a quart of water into the dishwasher drain.


Then I ran the dishwasher until I could hear the pump run. If this dishwasher had a manual timer (a rotary dial with many positions) I would've turned it to a point in a rinse cycle, turned on the machine and manually advanced the timer until the pump ran.

Since this appliance had an electronic control, I selected a short cycle (rinse only) and pressed the ON button. I heard the fill valves open (they made a slight hum) but nothing else. When I pressed the CANCEL button, the pump ran for a short period. That's all I needed.

Running the dishwasher to push antifreeze through drain.


Adding RV antifreeze to a washing machine to protect the pump. I poured about a quart of antifreeze into the clothes washer...


...then I turned the control to the SPIN cycle and pulled the knob to start the machine. I let the washer run for about 30 seconds, until I could no longer hear any water going down the drain. Running the washing machine.


Washing machine drain hose, antifreeze needed in this drain. I suppose some antifreeze got into the washing machine drain, but I couldn't be sure. So I pulled the drain hose out and poured in a cup of antifreeze.


The Refrigerator Icemaker:

The other water-containing appliance in a typical house would be the refrigerator, if it was equipped with an icemaker. The frig in this house didn't have an icemaker. If it did, I would have pulled the refrigerator away from the wall and disconnected the icemaker water line and let the water flow out into a pail. Any water remaining in the appliance should be fine (it's meant to freeze).

Furnace-Mounted Humidifier: It may be necessary to manually open the humidifier float valve to let the water drain out. Many humidifiers have a basin of water that may need to be drained. Do not put antifreeze in a humidifier, it'll ruin it.


The Furnace:

You wouldn't think that a furnace would contain water, but some do. High-efficiency furnaces (also called condensing furnaces) generate a significant amount of condensation from the water vapor in the flue gases. These furnaces always have a condensate drain line. Sometimes the condensate drains into a floor drain, but if there's no drain available the condensate drains into a small pump which pumps the fluid uphill into the plumbing drain.

You can tell this is a high-efficiency furnace because the chimney is the white plastic pipe visible in the upper right of the picture.

High-efficiency gas forced-air furnace.


Furnace has condensate drain and pump. The condensate pump (1) was located just above the floor. This unit contains a small electric pump, a plastic basin for the water, a float device that turns the pump on and off.

Arrow 2 points to a gray plastic trap device on the side of the furnace. Two small white plastic tubes lead into this trap, and a larger plastic tube drains the trap into the condensate pump.

Arrow 3 points to the flexible plastic discharge tube that leads from the pump to the drain pipe.


I poured some RV antifreeze into the trap. As I poured, the pump kicked on. I continued to pour antifreeze into the drain until I saw some pink color in the discharge tube. Pouring RV antifreeze into furnace condensate drain.

Note that this discharge tube is always filled with water... at least up to the level where the tube turns downhill and goes into the drain. I suppose that if this flexible vinyl tubing were to freeze it might not rupture. And if it did rupture, it wouldn't be too difficult or expensive to replace it. My biggest concern was the pump itself, which could be damaged if water froze inside. The last time I bought one of these pumps it cost about $50.

Shutting off power to the furnace. When I was done putting antifreeze in the condensate drain system, I turned off the power to the furnace. A few days later the homeowner had the gas company turn off the natural gas. Even when no gas is consumed they still charge a service fee of $8.50 per month


Hot Water Heating Systems:

A hot water (or hydronic) heating system would also need to be drained if the heat was going to be shut off during the winter. Draining a hydronic heating system is slightly more complicated than draining the potable water system.

1. Shut off the power to the boiler.

2. The "make up" water supply needs to be shut off. All hydronic heating systems have a connection to the cold water supply, and there is always a shutoff valve on this line.

3. The system drain needs to be opened. There will be a drain valve at the lowest point in the system.

4. Air needs to be allowed in. Every radiator should have a bleeder valve, which is typically a small cap on the elbow at the end of a baseboard radiator. Old cast iron radiators have a bleeder valve near the top, which can be opened with a special key (available at a plumbing supply or hardware store). Needle-nose pliers work too.

All of the bleeder valves need to be opened while the water drains out. This can take a while, perhaps an hour.

Refilling: All of the bleeder valves need to be opened. The system drain needs to be closed, of course. The make-up water supply valve is opened. When water spurts out of a bleeder, close it. When all of the bleeders have been closed the system can be run. Odds are you will hear occasional gurgling sounds as air bubbles circulate through the system. Many systems have an automatic bleeder valve above the boiler that lets these bubbles escape. Otherwise it may be necessary to open a bleeder to let the air out. First try the highest bleeder in the system, because air will often accumulate at the highest point.


Well Water:

If a house has a well instead of municipal water, then the well pump needs to be shut off and the pressure tank drained.

To turn off the well pump, the breaker can be turned off, or look for a disconnect switch near the well tank.

A well system can be emptied at the pressure tank drain valve (red arrow).

This valve is often close to the floor, so a short garden hose is helpful. The last few gallons will need to be drained into a shallow container, such as a dishpan or cake pan.

Draining a well pressure tank with a garden hose and bucket.

If the entire system is drained through this valve, the water heater will still need to be drained.


More Info:

Tools Used:

  • Flat Blade Screwdriver
  • Plastic Pails (2)
  • Adjustable Wrenche
  • Channel-Lock Pliers
  • Toilet Plunger

Materials Used:

  • RV Antifreeze, 2 Gallons
Related Articles:


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Written February 7, 2008