RV Water Pump Not Working When Winterizing: Best Quick Guide

Autumn is a wonderful time of year.  It brings up fond memories of beautiful leaves, pumpkins, and most of all, the time to winterize your RV.

As the cold weather approaches, the concern for your fresh water lines freezing is right around the corner.  It doesn’t take much for an RV water line to freeze and cause expensive damage. So, getting some RV antifreeze in your plumbing lines makes perfect sense before it’s too late.

You are far ahead of making this an easy annual choir when you have a water bypass system. You put the winterizing hose into the antifreeze jug and let the water pump do its thing. But what should you do when this doesn’t work?

The most common reason your RV water pump is not working when winterizing is an open valve or air in your plumbing lines. This post will review how you can determine the cause and fix the issue, including:

  • How your RV pump needs water pressure
  • Checking the water level in the fresh water tank
  • Getting rid of air in plumbing hoses
  • Checking valves are in the correct position
  • Checking valves are not leaking or need replacement

Whether you have an RV, travel trailer, or a fifth wheel, all these methods apply to your winterizing system.

Table of Contents

Water Pressure

As we dig into the issue, the first thing to know is how the water pump works.  A simple overview is that the pump takes water from the fresh water tank and distributes the water to your faucets, water heater and outdoor shower (no surprise there).

Your RV pump needs to create water pressure to get the water flow.  Similar to city water, they use massive pumps that carry that pressure throughout the town.  Your RV water pump, on the other hand, is small and only needs to create water pressure (around 35 psi) for your RV. 

As your RV pump operates, a pressure switch will turn on and off as needed.  When the faucet is used, the pressure sensor senses the reduced pressure and turns back on.  The pump turns off once the water pressure is back to where it should be.

However, the pump cannot create water pressure or operate properly if any valve is open or air in the line. This can also affect when you are trying to get antifreeze into your plumbing lines.

Fresh Water Tank

If you read any of my other posts, you will know I usually like to start with the simplest and easiest solution.  It seems that most times, that is what the common cause was.  Plus, since it’s the easiest, it takes less energy to try it and move on to the next solution.

Water in fresh water holding tank

For your pump to work, even when winterizing, it needs water pressure and no air in the lines. If your fresh water tank is low, it may be sucking up some air and causing a loss of water pressure.


If you suspect the water level is too low, fill it with water.  You don’t need a full tank, but at least a quarter-full tank will work. 

Next, you must get the air out from the plumbing lines. To do this, you need to go to every faucet and plumbing fixture.  Start with the farthest fixture, and this can be an outdoor shower.  Turn on the hot and cold water until all the air is out and you have a good water flow. 

Then go to the remaining faucets and toilet(s).  Operate them all until the sputtering air stops, and you have that consistent water flow. If all is working well, complete your winterizing process as usual and drain the remaining water from your fresh water tank.

Check Valves

If you have removed all the air out of your plumbing system and you are still not getting antifreeze flowing from the gallon jug, the next step is to check the valves to see if any are open or leaking.

Bypass Valve

Bypass valves are great! They make this annual task a simple process and avoid all that wasted antifreeze going into the water heater.  Even a small RV water heater is three gallons.  You can avoid three gallons of waste by simply using your bypass valve.

For the bypass, or winterizing valve to work, you need to turn off the valves to the hot water tank and open the valve at the water pump.  What this does is isolate the water heater or in other words, “bypass” it.  Then, turning on the valve at the water pump opens the winterizing hose and disconnects the line from the fresh water tank. 


If this sequence is incorrect or there is a leaking valve, the water heater will fill up with antifreeze, or the winterizing hose will not even take fluid from the antifreeze jug. 

Check your valves are in the correct position.  For more information, you can visit my post on hot water heater bypass valves.  There, you will get more information on the location and operation of your bypass system.

Low Point Drain Valve

Another potential source for air to get into the system and cause the RV pump not to work is the low point drain valves.  These valves are located at the outside of your RV and are there so you can easily get any water out of the plumbing system.

The Low point drain valves can be leaking.

Sometimes, these valves do leak and can cause air to enter the system.  Since they are outside, many RV owners may be unaware of this issue. 


Check to see if your drain valves are leaking.  If water is dripping, tighten the valve or the drain plug.  These valves should be dry, so if you touch them and there is water, you may have a slow leak.  If tightening does not fix the leak, you may need to replace the valves. 

Final Thoughts

As the cold weather approaches, so does the need to winterize your RV.  When your RV water pump is not working when winterizing, there are a few simple steps you can do to fix the problem.  The first step is to confirm you have enough water in your fresh water holding tank.  RV pumps cannot create the water pressure needed if there is air in the line. To remove air from your plumbing system line, open all faucets and plumbing fixtures until all air is removed and the water flows consistently.  Next, check that your bypass system is correct, with proper valves turned on and off.  Finally, inspect for any valve leaks where air can enter the system.  The low point drain valve is a common leaking point and is often overlooked due to its location outside the RV.