How To Make Sure Your RV Hot Water Tank Is Full: Best Answer

So how do you know when your RV hot water tank is full? Unfortunately, there are no gauges and no clear way to tell. Most motorhomes and RVs have many gadgets and gauges, yet no clear way exists to know if the hot water tank is full. With just a few quick steps, you will learn how to have a full hot water tank in your camper.

In this post, we will review that the simplest way to check if your water tank is full , is by:

  • Checking for air pressure at the faucet

Knowing that air pressure is building up in your tank means that the tank is not full of water. This post will run you through what to check for if you are still getting air pressure in your tank.

Table of Contents

Water Pressure

The quickest and best way to tell if your hot water tank is full is if there is any air pressure coming out of the hot water faucet. Since your water heater is a “tank,” it is an area that will collect water and air pressure as your RV lines fill up with water. Once you start pushing water through your lines, either by turning on the water pump or being connected by city water, the air is replaced by water. As the water replaces the air, it becomes pressurized. That is why your RV faucets spit and push out air whenever you refill your water lines.

When it comes to your hot water tank, it will either have water or air in it. When your hot water tank is full, you will have consistent water pressure on the hot side of the faucet. If you are mainly getting pressured air and spitting water, your hot water tank still has air and is not full.

The best way to get that pressure out of the water lines and the tank is to keep that faucet open until there is consistent water pressure. I suggest you go to every faucet in your RV and turn on the hot water until all the pressure is gone. That will get rid of any air packets that may be scattered in other parts of your RV.

So what happens when you can’t get consistent pressure and your hot water is not full? Here is a list of things to check out.

Drain Plug

First, you want to ensure the drain plug is capped and not leaking. Any drain plug leaks will cause hot water to escape and will not allow your water lines to pressure. Whether you have a diode or diode-free hot water tank, check that the drain plug is tight and leak-free. Any leak in the drain will introduce air into the tank and not make the tank full.

Pressure Relief Valve

Check the drain plug and pressure relief valve.

Make sure the pressure relief is sealed and not leaking. If there is water at this valve, it could be that it is doing its job and letting out the over-pressured air. But it could also be a sign of a leaking valve.

Bypass Valve

If you are in a cold weather part of the country and need to winterize, you probably are very familiar with bypass valves. These valves bypass the heater tank, so you don’t need to fill will with antifreeze completely.

Check your valves to see if they are in the open portion and if fresh water is going into your heater tank.

Water Pump

If you get your fresh water from your RV holding tank and use the water pump, check that the pump is functioning properly. Once you turn on your water pump, you should hear the pump working. It usually runs for a few minutes as the water lines and the tank fill with water.

Check water pump

If it seems your pump is running excessively long (more than 3 minutes) to fill the tank, it could be a weak, clogged, or failing pump. With a weak pump, pushing out the air and filling the hot water tank with fresh water will be difficult.

Water Filter

At your water pump, you will have a water filter. This will take the cold water from your holding tank and remove debris before entering your tank’s heating element. Water lines often get filled with debris from the RV construction, and the filter can get clogged, causing weak water pressure. Check the filter and replace it if dirty or looks like it is causing a weakness in the water pressure.

Final Thoughts

There are no gauges to tell you when your hot water tank is full. But the good news is that you can determine your hot water tank is full by simply opening the hot water side of your faucet until a consistent flow of water comes out.