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RV Hot Water Tank Not Filling Up

Are you facing the frustrating issue of your RV hot water tank not filling up?

Don’t worry, you’re not alone!

Many RV owners encounter this problem at some point during their travels.

In this comprehensive troubleshooting guide, we’ll explore the common reasons behind this issue and provide you with practical solutions to get your hot water flowing again.

So, let’s dive in and discover what could be causing your RV hot water tank not to fill up and how you can fix it!

RV Hot Water Tank Not Filling Up: Possible Causes

1. Insufficient Water Pressure

Have you checked the water pressure in your RV?

Insufficient water pressure can prevent the hot water tank from filling up properly.

To test the pressure, connect a pressure gauge to an available water source in your RV and measure the reading.

Ideally, the pressure should be around 40 to 60 psi (pounds per square inch).

If the pressure is too low, it may be due to a clogged water filter, a faulty water pump, or an issue with the campground’s water supply.

To address this issue, try the following steps:

  1. Clean or replace the water filter: A clogged water filter can restrict water flow, causing low pressure. Consult your RV’s manual for instructions on how to clean or replace the filter.
  2. Check the water pump: Inspect the water pump for any signs of damage or malfunction. If necessary, replace the pump or consult a professional for assistance.
  3. Contact the campground: If you’re at a campground, inform the management about the low water pressure issue. They may be able to address the problem or provide an alternative water source.

2. Faulty Check Valve

A faulty check valve can also lead to a hot water tank not filling up.

The check valve prevents backflow and ensures water flows in one direction.

If the check valve becomes stuck or damaged, it can obstruct water flow into the tank.

To troubleshoot this issue:

  1. Locate the check valve: Consult your RV’s manual to find the location of the check valve. It is typically located near the water heater.
  2. Inspect the check valve: Check for any visible signs of damage or debris. If you notice any issues, you may need to replace the check valve.
  3. Replace the check valve: Remove the faulty check valve and install a new one. Refer to your RV’s manual for specific instructions or seek professional help if needed.

3. Airlock in the Water System

An airlock in the water system can prevent the hot water tank from filling up.

Air can get trapped in the plumbing lines, hindering the flow of water.

To eliminate an airlock:

  1. Open all faucets: Turn on all faucets in your RV, both hot and cold, and let the water run for a few minutes. This will help release any trapped air in the system.
  2. Bleed the lines: Locate the water lines and look for bleeder valves or air release valves. Open these valves to release any trapped air. Be sure to close them once water starts flowing consistently.
  3. Check the water heater bypass valve: Some RVs have a bypass valve that diverts water flow around the water heater. Make sure it is set correctly to allow water into the tank.

4. Defective Water Heater Element or Thermostat

A defective heating element or thermostat can cause the hot water tank not to fill up or heat the water properly.

Over time, these components may wear out or malfunction, requiring replacement.

To troubleshoot this issue:

  1. Test the heating element: Use a multimeter to test the continuity of the heating element. If it doesn’t show continuity, it is likely faulty and needs to be replaced.
  2. Check the thermostat: Test the thermostat in a similar manner. If it’s not functioning correctly, replacing it may solve the problem.
  3. Replace the faulty components: If either the heating element or thermostat is defective, follow the manufacturer’s instructions to replace them. If you’re unsure, consult a professional to ensure proper installation.


Why is my RV hot water tank not filling up even though the water pump is running?

If the water pump is running but the tank is not filling up, it could be due to a clogged water line, a faulty check valve, or an airlock in the system. Refer to the respective sections above for troubleshooting steps.

Can a low RV battery cause the hot water tank not to fill up?

Yes, a low RV battery can impact the performance of the water pump, which may result in the hot water tank not filling up properly. Ensure that your RV’s battery is charged and in good condition.

What should I do if none of the troubleshooting steps work?

If you’ve tried all the troubleshooting steps mentioned above and your hot water tank still doesn’t fill up, it’s best to consult a professional RV technician. They have the expertise and tools to diagnose and repair complex issues.

Is it possible to repair the water heater element or thermostat myself?

Repairing the water heater element or thermostat requires technical knowledge and expertise. It’s recommended to consult a professional for repairs to ensure proper installation and safety.

Can hard water affect the hot water tank filling up?

Yes, hard water can cause mineral buildup in the hot water tank and plumbing lines, leading to reduced water flow. Regularly flushing and descaling your RV’s hot water system can help prevent such issues.

How often should I maintain my RV’s hot water system?

Regular maintenance of your RV’s hot water system is essential to ensure its proper functioning. Follow the manufacturer’s guidelines for maintenance intervals and perform routine inspections to catch any issues early on.


Experiencing an RV hot water tank not filling up can put a damper on your camping adventures.

However, armed with the knowledge and troubleshooting steps outlined in this guide, you’re now equipped to tackle this issue head-on.

Remember to check water pressure, inspect the check valve, release airlocks, and test the heating element and thermostat.

In case of persistent problems, seek assistance from a professional RV technician.

Now that you’re well-prepared to handle the hot water tank not filling up issue, get back to enjoying your RV travels with the comfort and convenience of a fully functional hot water system.