RV Shower Not Draining? Here’s Why & Fixes

So, you step into your RV shower to get clean, but the shower just won’t drain. Having that water buildup around your feet and realizing there is a problem is a frustrating situation and a quick way to ruin your day.

I have personally experienced problems with my shower draining twice before so don’t panic if you have found yourself in the same frustrating situation, in most cases, it’s something that you can fix by yourself fairly quickly.

I am going to cover all the common causes, and most importantly how to fix your shower drainage problems so you can get your shower back up and running as quickly as possible.

So why is my RV shower not draining?

Common causes of an RV shower not draining include a full gray water tank, a closed drain line valve, the RV’s air admittance valve not working properly, blocked plumbing, and a shower that drains into the black water tank.

Let’s take a closer look at all of the common causes as well as the solutions.

RV shower not draining

7 Reasons Why Your RV Shower Won’t Drain + How To Unclog

Let’s get right to it and take a look at exactly why the shower in your RV might not be draining. There are seven main reasons, and we’re going to start with the most common one and tell you what you need to do.

1. A Full Grey Water Tank

The grey water tank in your RV is the tank that holds the water that comes from the showers and sinks. If the grey water tank is full, it is the simplest explanation as to why the shower isn’t draining. The bathtub or shower drain is usually going to be the lowest drain in your RV. 

Therefore, the shower or tub is going to be the first place where the water backs up if the grey tank is full. Simply put, it’s going to overflow. 

If the indicator lights for the grey water tank indicate that it is full, then you know what the problem is. However, these gauges can sometimes be inaccurate. If the water is coming up through the shower drain, this might just be the problem.

Solution

First, you do want to check the indicator gauge. If you see that the tank is around 3/4 of the way full, then you will need to go empty it.

Even if the gauges show that there is a bit of space left, you still want to try draining it anyway. If draining the tank solves the problem, then you are good to go. 

If the gauge is not working properly, you will also need to take the appropriate steps to solve the issue. You may have to troubleshoot the gauge, or it may have to be replaced.

You do want to check water tank levels on a regular basis to prevent this problem from occurring. If this does not solve the issue, move on to the next section. 

Related: Guide on draining your fresh water tank.

2. A Closed Grey Water Tank Drain Line

Although this is a very simple problem, not opening up the drain line from the grey water tank to the sewer hose is something that does happen. 

Simply put, you might just have forgotten to open the valve that leads from the grey water tank. This could mean that your grey water tank is full, but not draining into the sewer line that you have it connected to.

Solution

To solve this issue, you do first want to make sure that the grey water tank valve is connected securely to the sewer hose. You then just have to pull the lever to open the valve. 

If the valve is open, but your shower still isn’t draining, and the grey water tank is not full, then it is a different problem that is to blame. 

Something that you do not want to do however is to leave the grey tank valve open at all times. You do not want it continuously draining into your sewer, as this can cause sewer smells to come up in your RV.

3. The Air Admittance Valve Is Malfunctioning

The air admittance valve in your RV is a component that helps to ensure that the drain system is vented properly. You will usually find this air admittance valve somewhere under the sink or shower between the drain line and the P-trap. 

This allows enough air to get into the system to balance the pressure to allow water to flow down into the waste pipe. 

It also helps prevent sewer gas from getting in your RV through all of the drains. If air cannot get in, then water will not flow properly. If it is damaged or clogged, then it won’t be able to open up to allow air in.

Solution

You need to check the air admittance valve to make sure that it is properly attached by securing all of the fittings. Make sure that if it is installed vertically, that it’s not blocked by anything. If the valve itself is installed properly but is not working, then it most likely will need to be replaced. 

These things can break down, and they are extremely hard to repair, so will most likely need to be replaced. You first may try removing it and then draining your grey water tank and then reattaching it.

This can sometimes solve the problem, although not very often. If this doesn’t work, a replacement valve is called for. 

Camper shower

4. A Clogged Shower Drain

If your shower is not draining, perhaps the most obvious cause is that it is simply clogged. If the tank is not full, the tank valve is working, and the airflow is right, then a clogged shower drain is the next possible explanation.  Things like hair, grease, and food can all build up in the shower drain.

Solution

Of course, there are a number of solutions to a clogged shower drain. The first thing you can try doing is to flush some boiling hot water down it along with some dish soap. Make sure that the water is extremely hot, and that you use at least a gallon of it. 

If hot water does not work, a more hands-on approach is to use a sink plunger. Simply plunge the shower drain to try to force any obstacle out the other end. If this does not work, then the next solution is to use a drain snake or drain auger. Place the auger in the drain, extend it, and twist. If there is a blockage, you should feel it. 

If the drain auger does not work, you may have to use some kind of enzymatic base to drain unclogger. Be aware that for RV’s, you need extremely special drain unclogging liquids and cannot use something like Drano.

Things like Drano will cause damage to your pipes and RV’s grey water tank system. If none of these solutions work, you will probably have to call in a professional for help.

On a side note, beware that the hose that is attached from the valve to the sewer may also be clogged. You can listen to see if it is flowing, or you can even look inside of it. This hose can be easily detached and rinsed out.

5. Clogged Plumbing Roof Vents

All RVs are going to have roof vents for the plumbing. These roof vents allow for proper air pressure regulation. This also allows gases to vent away from the RV. These vents are required proper drainage. 

These vents go all the way from the drains up to the roof of the RV. All kinds of debris, dirt, and even animals, as well as animal nests, can get into these air vents. Moreover, if the vent is damaged, it may also cause an airflow and water flow disruption. If air cannot vent, then water cannot flow. 

Keep in mind that if this is the problem, you will most likely also hear your toilet gurgling, and there may also be sewage smells that are coming out of all of the drains.

Solution

To check for this problem, you are first going to have to climb up onto the roof of your RV. You are then going to have to check the vent opening to see if there is any debris inside of it. You are going to want to use a water hose and put some water into the main vent. 

If running some water through the vents does not solve the problem, you may have to clean out the vent pipe. You may have to use your hands or other tools to clean that vent pipe out of any obstacles. You can always reach in and pull out whatever you can get hold of. 

You may also use a drain auger or drain snake to go deeper down into the pipe if you need to. Once you have done this, run some more water into it to see if it works. If this does not solve the issue, unfortunately, you will most likely have to call a professional for help.

6. A Clogged P-Trap

Showers usually always come with P traps. The P-trap is a U-shaped pipe that you will see under a sink or a shower. This P-trap is designed to hold a very small amount of water that helps to prevent sewer gases from coming up through the pipes. 

You could see an extension pipe attached to the J pipe or one solid pipe right below the drain hole of the shower. Just like with P-traps in sinks, the P-trap under an RV shower can also get clogged. If your P- trap is clogged, water is going to sit right at the shower drain.

Solution

The solution here is of course to clear that trap of any obstacles. You can first try using a good old plunger to see if you could force the clog through the P-trap. If this does not work, you can always pour some boiling hot water along with some vinegar and dish detergent down the drain. 

If you have a bristle brush, you can try shoving it down there to see if you can clear up the clog. If this does not work, you can then use a plumber snake or drain auger to try and clear out the issue.  Just put the auger in the drain twisted and see if it gets hold of anything. 

If this does not work, then you might want to use a special type of drain cleaner design for RV’s. Remember that these need to be enzymatic drain cleaners, not something like Drano, as Drano can cause damage to your pipes and to the greywater system. 

If this does not work, you may want to remove the drain trap and the P-trap to see if you can manually clear it out. If all else fails, and the P-trap is still clogged, you will need to get a professional to solve the issue for you.

7. A Shower That Drains Into The Blackwater Tank

Although this is extremely unlikely, it could be the case that you have a special type of RV where the shower actually drains straight into the black water tank instead of the grey water tank. In most cases, this will mean that your RV does not have a grey water tank at all. 

There are RV’s where all water drains into the same tank, which would be a black water tank. If your shower is backing up with black water, you’re definitely going to be able to tell, as this is generally just water mixed with raw sewage. 

Solution

The first thing that you want to do is to drain all possible tanks, whether the grey water or the black water tank or both. If you only have one tank, drain it. 

Besides the fact that you only have a black water tank, this backup could also be caused by any of the other above problems. 

However, instead of the backup being caused by a clogged or faulty valve between the shower and the grey water tank, the issue is going to be caused somewhere along the connection between the shower and the black water tank.

Conclusion

If you have made it this far then we hope you have been able to successfully unclog your RV shower drain, the 7 issues we have covered are the most common reasons why an RV shower won’t drain.

If you have tried all of the solutions and are still experiencing problems then you will have to resort to calling in a professional.

Madeline Cooper
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