Why Is My RV leaking Water Underneath? 10 Possible Causes

You woke up, opened the door, and stepped in a puddle of water. Oh no, your RV has sprung a leak from the underbelly and you are trying to figure out why, and most importantly how to identify and fix the leak.

Common causes for your RV leaking water underneath include a cracked water tank, a broken hose, a broken valve seal on the water filter, a broken grey or black water tank, or an overfilled water tank.

Here is a complete guide on each cause, locating the leak, fixing it, and lastly how to dry out the underbelly of your RV.

RV leaking water underneath

Why Your Camper Is Leaking Water From The Underbelly

As mentioned above, there are as many as 10 possible causes as to why your camper could be leaking;

1. Cracked Water Tank

The water tank that your RV has to hold fresh water for drinking, showering, and the toilet, may have a crack in it. If this has a crack in it, you are probably going to see a very large water puddle, as these tanks hold plenty of water.

2. A Broken Hose

Your RV is going to have a few different hoses, including the one that leads from the water spigot to your water tank, as well as the one that leads from the water tank to the various amenities inside of the RV.

These hoses aren’t the most durable, and they can crack or even totally break. It’s not uncommon for one of these hoses to have a hole in it.

3. A Broken Valve Seal

The water pump in your RV has a special valve seal to keep it closed when it is not in use. These valve seals do get old, and it may be broken. If this is the issue, you might also have trouble pumping water.

4. Issues with the Water Filter

Your RV most likely has a water filter to help clean the water before it comes out of the shower, into the toilet, or even out of the sink.

These water filters do have special seals to ensure that they are watertight. If one of these seals breaks or malfunctions, your RV will spring a leak from the bottom.

5. Water Heater Issues

The water heater in your RV is a large tank that holds water and heats it up. If one of the valves or seals on this hot water heating tank is broken, your RV will spring a leak.

Moreover, these hot water tanks themselves can also crack or break, which would result in a massive leak.

6. Issues with the Water Faucets

Water faucets, especially in the pipes underneath, have a variety of components including washers. If these washers are no longer good, then your kitchen faucet and the RV may leak and cause water to pool underneath it. This may also be the case for the sink in your bathroom.

7. A Cracked Shower

Showers use a whole lot of water, and that water goes down the pipes into the grey water tank. However, if the basin of the shower, or in other words the shower tray or floor of the shower is cracked, that water isn’t going to make it into the pipes, but rather leak down through the floor of the RV.

8. Broken Grey Water Tank

The grey water tank in your RV is the tank that holds relatively clean water that comes from your sinks and showers. If this grey water holding tank is cracked or broken, it is going to cause a massive leak to occur.

Related: How to drain a grey water tank.

9. Broken Black Water Tank

The black water tank in your RV is the tank that holds your sewage waste, or in other words, whatever comes out of your toilet.

If this tank is cracked or broken, not only will you have a massive leak, but you’re definitely going to be able to smell it as well.

10. Overflowing Tanks

The other possible cause of a leak happening below your RV is if you have overfilled the fresh water tank. As well, failing to empty either the black water or the grey water tanks can also result in leaks and water buildup to occur.

How To Locate And Fix A Water Leak Underneath Your RV

OK, so you know that your RV has sprung a leak underneath, but where is it coming from? It could of course be due to any one of those issues that we have discussed above. However, to remedy the situation and stop the leak, you first need to identify where that water is coming from.

The first thing that you want to do here is to get your RV’s owner’s manual, so you can examine exactly what the water system in your RV looks like. Once you have done this, you are going to follow the steps listed below in order to find that leak.

  1. The first thing you want to do here is a pressure test. Therefore, you want to drain all of the water from the system and keep all of the faucets closed. You will also want to empty the toilet.
  2. You will now attach the air compressor complete with a pressure gauge to the inlet valve where your RV takes in water. You are now going to inject a lot of air into the system at around 100 pounds per square inch.
  3. Wait for about 10 minutes at once having injected the air. If the pressure on the pressure gauge has dropped, then you have a leak.
  4. What you are going to do now is to listen for a hissing sound. This is where all of that air is going to be coming out, and also therefore where the water will leak out. If this doesn’t produce any results, move on to the following step.
  5. You are going to use the necessary tools to unscrew the rubber underbelly from the frame of the camper. If any insulation material is waterlogged, get rid of it.
  6. You’re now going to use a good flashlight and take a closer look at all of the hoses coming from the black water, grey water, and fresh water holding tanks.
  7. You are now going to get your air compressor out again and inject around 100 PSI of air into the system. You are going to listen for a hissing sound and look for a spray of water coming out from the underbelly.
  8. If this doesn’t work, you’re going to refill the whole system with water and visually see where the leak is coming from.

Tips For Drying Out Your RV Underbelly

Once you have located and repaired the source of the leak, you will have to dry out the underbelly of your RV. You don’t want to leave it wet, as this can cause corrosion to occur. 

Leaving the underbelly of your RV wet may also cause mold to start to build up. Follow the tips and steps as listed below to dry out the underbelly of your RV as quickly and as efficiently as possible.

  1. Start physically removing any and all water buildups as well as you can. You might want to use something like a wet-dry shop vacuum for this purpose. Towels and other such things will all come in handy here. The point is that you want to suck up any excess moisture you can.
  2. If there is water in some of the crevices, the next thing you will want to do is to blow it out with air. The best thing you could use here is some kind of leaf blower, and this will physically drive water out as well as dry the area at the same time.
  3. If a leaf blower is not an option, using some powerful air fans is your next best bet. These might not drive the water out per se, but they will cause it to evaporate and dry much faster.
  4. Of course, having good airflow is essential, so you should park your RV in an area that is quite windy.
  5. In order to dry out the underbelly of your RV, you should also park your RV in an area where the ground is very dry and hot. So, on a summer day, park the RV on black pavement, as this will be very hot, and cause that water to dry up fairly quickly.
  6. Some people may also recommend poking extremely small holes in the underbelly of the RV, as this will allow water to flow out and air to flow in. However, you do have to be careful because you don’t want to make the holes large enough so that rodents and other pests can make their way in.

How Do I Stop My RV From Leaking?

If we are talking about a leak from the underbelly due to any of the reasons we have discussed today, then the simple solution to stop this from occurring is to engage in regular maintenance. 

Whether we are talking about cracked water tanks, broken pipes, or broken valves or seals, regular maintenance will help prevent this from occurring. Barring some kind of physical damage or extreme accident on the road, these things don’t just break on their own. 

They take a while to break down, so if you engage in regular monthly maintenance and inspections, you should be able to prevent the RV from leaking from underneath. Take your time about once per month to inspect all of the elements that we discussed in the first part of this article.


You should now be aware of all of the possible causes of your camper leaking. You should also know exactly how to find that leak. Of course, when it comes to fixing the leak, this might be something that you cannot do on your own and may require professional assistance.

Madeline Cooper