How to Unclog An RV Black Tank

How to Unclog An RV Black Tank


George Cummings
November 23, 2021

As disgusting as the thought may be, you will come across problems with your RV’s black tank from time to time.

One of the most common and unpleasant problems that RVers face is a clog in their black tank, and if this has happened to you, you’ll no doubt be looking for a simple fix.

How do you unclog an RV black tank?

There are a few methods you can use to unclog a black water tank including using additional chemicals in the tank and cleaning it out with a plumbing snake.

You may even need to utilize a couple of these together to solve the problem if the clog is bad.

One of the downsides of the RV lifestyle is dealing with potentially gross issues like this, but it doesn’t have to be as bad as you imagined.

We’ve got some helpful tips and the steps to take to get it unclogged, so read on to make your life (and black tank) a little better.

Why Does the RV Black Tank Get Clogged?

Why Does the RV Black Tank Get Clogged?

As your traveling sewer system, it’s natural that you’ll run across problems with your RV’s black tank, just like you do with the toilet at home.

However, because there’s no real sewer system connected to the RV, the black tank is responsible for storing all of the waste on board until you’re able to empty it.

Not only does this tank hold old water from the toilet but also human waste and toilet paper, and it arrives there after traveling through a pipe.

We add a simple chemical to the tank that helps to break all of this down so that it’s easy to dump when it’s time, but all sorts of issues can arise that cause clogs, including:

  • Emptying it too often: If you empty the tank too often, its interior will dry out which causes toilet paper and other things to stick to the wall. When too much of this build up, you’ll clog the black tank and cause obstructions.
  • Flushing the wrong things: The only two things that should go inside your RV toilet are human waste and RV-friendly toilet paper. Anything else will ultimately lead to issues with your onboard sewerage system.
  • Not enough emptying: When you don’t empty your RV black tank as required, the waste inside will build up and cause issues. Some tanks come with a sensor that lets you know when it’s time, but these can malfunction as well, so you need to assess it regularly for yourself.

How to Unclog RV Black Tank

Before we jump in and start unclogging the black tank of the RV, we want to diagnose the problem and make sure we’re doing the right thing.

The most obvious tell that you have a clog is by looking at the sewer hose and seeing if the liquid is draining adequately from the tank, which is why using a clear hose is recommended.

Secondly, you can usually hear how much liquid is draining from the tank, and if sounds like only a slight trickle or nothing comes out at all, this indicates a clog.

Once you’re sure this is what you’re working with, you can start to assemble the tools for the job.

When working on anything in your RV, safety is crucial, and even though you’re not touching wiring or fixing something under the hood, you still need to be protected.

Waste from the black tank is toxic and so too are the chemicals you’ll use to clean them, so at the very least you’ll want some protective goggles and gloves that are suitable for this type of job.

Tools and Equipment

  • Protective goggles
  • Gloves
  • Plumbing snake
  • Tank chemical

The Simple Steps

  1. Keep yourself protected by wearing the goggles and gloves you have.
  2. Start with the pipe that connects the toilet to the black tank and insert the plumbing snake to try and loosen any clogs.
  3. Once that’s clear, use a dedicated waste tank cleaner and insert it into the black tank.
  4. Allow the chemical time to work and then attempt to empty the tank again
  5. Once empty, run some water through the pipe to see if the clog has been rectified.
  6. If it didn’t work, use a stronger tank cleaner to break down the waste and obstruction, and then attempt to rinse it out again.

Tips for Preventing Future Problems

Tips for Preventing Future Problems

We want to spend as little time as possible messing with the black tank of our RVs, and more time on the journey ahead.

As such, we’ve got some tips you can follow to ensure your black water tank is kept in the best condition and free from obstructions.

  • The right paper for the job: Choose your toilet paper wisely and don’t assume you can bring a few rolls from home and it’ll be the same. RV-friendly toilet paper is easier to degrade and won’t lead to obstructions in your tank so it’s worth spending a little extra to get the right kind.
  • Avoid the pressure washer: Some people will recommend using a pressure washer to clean out the pipes of your black tank, but this can get messy. If you take this approach, there’s a good chance you’ll send waste flying all around, so it’s not recommended.
  • Stick to a plan: Have a schedule in place for emptying the water tank and stick to it. Doing it too often or not enough can cause a build up of waste or dryness in the tank that leads to blockages, so it’s important to know what’s required of your tank and the right cleaning schedule for how often it’s used.
  • Be prepared: Any smart RVer has a kit ready to go for problems like this, and you should too. In your unclogging kit, you’ll want your safety gear, a trusty plumbing snake, and some super strength treatment to break down waste, so you’re always prepared.
  • Keep it clean: The easiest way to prevent problems with your onboard sewer system is to keep up with regular maintenance and care of the toilet and tanks. Take some time to learn the processes involved, what you can and can’t do, and what chemicals and products are required regularly.
  • Use boiling water: If you’re stuck on the road and can’t get anywhere to empty the black water tank, you can use some boiling water to free up the problem. Boil a lot of water and pour it into the toilet bowl then let it sit there for an hour before attempting to flush again. Sometimes this is enough to loosen up any obstructions until you can park and rectify the issue.

A Trouble-Free Black Tank

As one of the least glamorous parts of our RV, it’s no wonder that we dread the thought of cleaning out the black tank.

However, with a few savvy tips on getting the job done and some know-how about preventing clogs in the future, you can focus on better things in the RV, like your next exciting destination.

Related Questions

The various tanks in your RV play an important role in keeping you comfortable, clean, and healthy, but there’s a lot to learn about them.

If you want to find out more about the fresh, black, and gray water tanks in your traveling home, read on for a few FAQs that can help.

What Size Water Tank Does My RV Need?

Having enough freshwater is crucial when you’re traveling somewhere with any water hookups, so you’ll need the water tank to correspond to how many people will be using it and for how many days.

A general guide is that a six-gallon tank is good for two people over two days, and an eight-gallon tank is ideal for a solo traveler over a full week.

Where Can I Empty My Grey Water Tank?

Where Can I Empty My Grey Water Tank?

The contents of your grey water tank will be less toxic than the black tank, and some states even allow you to empty it on the ground.

However, the most responsible thing to do is try to find a sewer that it can be dumped into as this will enable the water to be treated properly so it can be reused, rather than being wasted.

Where Are the Tanks on My RV?

Most RV models have all three of their tanks located on the underside of the vehicle but it can differ depending on the type of RV you own.

This includes the waste or black water tank, grey water tank, and freshwater tank, coming in various sizes to suit the needs of the RV owners and make of the vehicle.


George Cummings

George Cummings enjoys connecting with nature, meeting new people, and making friends from all over the world. RVing and camping create the perfect opportunity for [him/her] to take part in these activities. After spending several years on the road and exploring the great outdoors, George Cummings shares some of his best pieces of advice on how to make the most of your time while camping. TourTheOutdoors is his way of helping outdoorsy individuals like [him/her] start on a right footing with amazing recommendations and buying guides.