Why Your RV Black Tank Leaks When Full? (Here’s How to Fix It)

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Do you own an RV or do you intend to rent one when going on holiday? There are a few things you need to know about RV tanks before they mess up your trip.

There are three tanks in an RV:

  • The first one is a Freshwater tank that stores fresh water.
  • The second is a grey water tank that holds dirty water from your kitchen sink and shower.
  • The last one is the black water tank. It holds dirty water from your toilet.

Some RVs might lack a Grey tank, the black tank contain all the dirty water from the kitchen sink, toilet, and showers. 

In this article, we shall focus more on the black water tank.

How to Maintain Your Black Water Tank

Since the black water tank holds the wastewater that is coming from your toilet, you shouldn’t mess around with it. Here are a few ways you can maintain it.

1. You don’t want to risk clogging your toilet. Then avoid using two-ply toilet paper. You should strictly use single-ply toilet paper.

2. Flush regularly – It is advisable that before flashing, ensure that you first add some water to the bowl of your toilet; then flash.

3. After dumping the waste, you need to sanitize the tank. Sanitization requires special chemicals. They are available in any big box store in the RV section.

4. Ensure that your tank is always clean. Your garden hose can help you to flush the system and clear up any build-ups. You’re required to put it down the toilet.

In case you realize that your black water tank is leaking, you have to get the solution faster. It can cause severe health issues. You can either decide to replace it or repair it.

Replacing can be expensive. You can choose to fix it before you invest and replace it later. Here are the steps you need to take.

1. Assess the Damage

In most cases, a damaged valve is the one that causes water leakage. The leakage also could occur if the tank has a crack. Repairing the valve and the crack is easy.

The hardest part will be if the leak is a result of the ruptured tank.

A ruptured tank means that your tank has exploded and cut split into two. Repairing that would be tricky and almost impossible since the damage is severe.

2. Fix a Crack

If you realize that the damage is a result of the crack, you have to sock the waste in your tank using sawdust.

The sandpaper will help you to smoothen that side of the crack. At the edge of that crack, add acetone and clean it thoroughly.

Apply a specialized sealant and let it dry. You can quickly get the sealant in the local repair shops. Since there could be excess sealant, you can use a cloth to wipe it.

You will realize that some service centers will not encourage you to repair your tank. Instead, they would like you to replace it. Reasons are:

  • They will make more profit if they sell a new one to you than when they replace it.
  • In case the repair fails, you might have a negative image of their business.
  • Some don’t know how to repair the tank, or they don’t want to.

Why Do RV Black Tank Leaks When Full?) Replacing the Tank

You can decide to replace your tank. You have to know the kind of material that it

is made of. Then you have to go shopping for such a tank.

In most cases, you will find stocks of standard-size tanks.

You will be lucky if your tank falls into this category since it has a few days’ leads and shipment time.

If your tank does not fall into this category, you can get one that will fit, or you can give an order for one to be built.

If your tank is below three years, you can quickly get another one from the manufacturer.

Once you get a new tank, you will have to remove the old one. The whole process of replacing can be costly as compared to that of repairs.

How Often Do You Need To Empty The Black Water Tank?

empty RV black water tank

It is a question that disturbs many people. In case you have been wondering the same, relax. The number of times will depend on the number of people you are traveling with. If you carry many people, you have to empty the tank daily.

If you are just two of you, then once for a week is okay. You should never allow the tank to get filled.

When it fills and starts overflowing, the process becomes much more complex. Empty immediately it gets to two-thirds.

Some recreational vehicles have sensors that will keep on alerting you on the level of the wastewater. Unfortunately, some sensors become unreliable as time progresses.

They either stop reading or read incorrectly. Some have errors even when the tank is new. You can be confirming manually to ensure that the reading on the sensor is okay. 

Other than the black tank, you also have to know about the fresh water tank and the draw water tank.

1. Freshwater Tank

Apart from the black water tank, you have also to maintain the fresh water tank.

RV freshwater tank

You should always fill your tank using a portable water hose.

In case you are wondering how you will recognize it, worry less.

They have a white color, and that makes it easy to spot them.

Weather is vital in the maintenance of this tank. When the weather is freezing, it is the right time to insulate your hose.  To prevent stagnation, ensure that you only drain your water when the heat is extreme.

If you realize that there is a foul smell from your tank, you have to clean it using bleach immediately.

2. Gray Water Tank

Your RV could be having two gray tanks. Since it holds water from your kitchen

rv gray water tank

sink and shower, you have to be careful not to clog it.

Avoid any food particles getting through it. Don’t ever underestimate a pea.


Before going on holiday using your RV, ensure that you clearly understand how to maintain your tanks.

You don’t want to come back with life-threatening diseases caused by the leakage. You have to know how to keep a black water tank, gray and even the fresh one.

In case there is a leakage, you can decide to do repair to your tank or replace it.

The cost of replacing could be a bit high. Unless the tank ruptures, you should consider repairing it.

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