How to Dump and Deep Clean Your RV's Sewer Tank in 5 Easy Steps

Updated on December 20, 2019
TIMETRAVELER2 profile image

I am a highly experienced RV owner who understands how important it is to keep my RV tanks clean and sanitized.

If you want your camper, travel trailer or motorhome to smell good, you need to learn the best methods for cleaning and sanitizing your coach's waste water tank.

A sewer tank that is not well maintained breeds bacteria that create horrible odors throughout a coach and also cause clogs in plumbing systems. Both of these things make using an RV a miserable experience, and both can lead to expensive repairs as well.

This is why knowing how to properly maintain your RV’s tank is important. This job

  • is not hard to do,
  • takes relatively little time,
  • will keep your RV smelling good, and
  • will keep your plumbing system functioning properly.

The good news is that you won't even have to get your hands dirty if you follow the tips in this article.


Step 1: Protect Yourself

What comes out of your sewer hose is toxic, so you need to protect yourself and your clothing by doing such things as wearing rubber gloves, shoe covers and protective glasses.

You should also keep some liquid soap and a roll of paper towels handy so that you can wash your hands, gloves and shoe coverings at an outside faucet after you finish the job and before you go back into your coach.

Step 2: Prepare to Dump

To dump, you need to be parked beside a sewer outlet. This will either be located at your campsite or a dumping station.

  • If you are at a dump station, connect the sewer hose to your RV and then place its end into the sewer opening.
  • If you are at a full hookup campsite, your hose likely will already be connected to your sewer outlet.

When your unit is stationary, always keep your waste water tank valve closed and your gray water tank valve opened. Before you dump, close the gray water valve, and fill it halfway with soapy water.

Step 3: Empty Your Tanks

It's very important to empty your tanks before they become full because liquid is heavy and too much of it can damage your tanks.

A gallon of water weighs about 8.34 pounds. So, if your tank holds 45 gallons, and you wait until it's full, it will weigh more than 375 pounds, which is more than enough weight to cause a problem.

You can avoid this issue by dumping when each tank is no more than half full. Doing this will also forces you to clean and sanitize tanks more often, thus helping you to avoid clogs.

How to Empty Your RV's Tanks

  1. When you are hooked up to a sewer outlet and are ready to dump, open the sewer tank valve. Once the waste matter has gone out of the tank, close the sewer valve, run fresh water into the tank, pull the valve and dump the contents again.
  2. Use a clear hose adapter so that you can see what is coming out of the tank.
  3. Keep filling and dumping until you can see that the water is running clear.
  4. Once it is, close the waste water valve and open the gray water valve.
  5. After doing this, allow the contents to empty into the sewer outlet. This will help to clean the interior part of the connector hose and keep matter from sticking to it.
  • If you plan to stay put, keep the blackwater valve closed, add a gallon of water and some Spic N Span to the sewer tank and keep the gray water valve open.
  • If you plan to drive your coach after dumping, close both valves, and place an enzyme cleaner along with about one gallon of water into the sewer tank.

As you drive, this mixture will

  • slosh around,
  • eat away at any hardened matter,
  • disinfect the tank and
  • help to eliminate clogs.

This will also eliminate any odors that may permeate your coach thus making it more pleasant for travel.

Step 4: Deep Clean Your Sewer Tank

Most people think that regularly emptying tanks is enough to keep them clean and sweet smelling, but this is not the case. When using a coach either for travel or living, people need to dump every few days and also deep clean at least once each week.

To deep clean, you follow all of the steps listed above except that before you open the gray water valve, you drain the waste water tank completely.

  1. Fill it 3/4 full with fresh water and two cups of liquid bleach.
  2. Close the toilet lid to avoid breathing any toxic fumes.
  3. Allow the mixture sit for 10 minutes, but no longer.
  4. Drain the tank.
  5. Fill it again with fresh water then drain it immediately.
  6. Continue to fill and drain until you see that the clear hose connector shows no debris, and the bleach smell has disappeared. This is very important to do because you need to make sure that there is no bleach left behind to damage your plumbing system.

Many people will advise you not to use bleach at all because doing so can damage your pipes and fittings, but I have used this method for more than 50 years and have never had a problem. The secret is to always mix it with a good amount of water and then eliminate it completely as soon as you can.

The fumes that you see rising are the result of the bleach eating away the hard sludge that sticks to the walls and floor of the tank. Using Bleach not only cleans your tank, but also sanitizes it, which is very important for your health.

Now it's time for you to pressure wash the inside of your sewer tank.

Step 4: Backwash Your Sewer Tank

The final step in deep cleaning a sewer tank is to backwash it. When you do this you are using pressurized water to push against the interior walls and floor of the tank in order to loosen and flush away hardened sludge and other matter.

There are two ways of doing this.

  1. Use a system that is built into your unit.
  2. Use hand-held equipment that attaches to your hose.

Built-In System Directions:

To use your coach’s system, connect a green garden hose to your RV's system connection and turn on the pressure washing valve located on your coach . Keep the water running until your clear hose adapter shows that the water is running clear.

Directions for Using a Wand:

To use an RV tank cleaning wand, you

  1. attach a green garden hose to your campsites water spigot,
  2. connect the backwash wand to the hose,
  3. pull the wand and hose through a window or door and into your bathroom
  4. open the flapper of the toilet,
  5. put the wand down the opening,
  6. have someone standing outside turn the water on for you and
  7. keep moving the wand back and forth around the tank until your helper see that the waste is running clear.

You won't be able to do a good job of pressure washing without using a clear sewer hose adapter because this gadget allows you to see when the hose runoff is free of debris and waste matter.

My husband and I have always used one that is made by Camco (can you tell that we like that brand?). It's inexpensive, durable and does what we need for it to do. Other brands also do a good job, but since Camco products have always served us well, we use them whenever possible

Backwashing Equipment

Many RVs have built-in backwash units, all of which do good jobs.

  • If your coach has one, your manufacturer's maintenance books will show you how to use it
  • If not have one of these units, you need to buy a wand that is made especially for RV tank pressure cleaning.

There are several types, but my husband and I use the one made by Camco called the Flexible Swivel Stik because it swivels and has a manual shut off, which makes it much easier to use than other types of wands. It is inexpensive, easy to store and works great.

We've used this one for years and have found it much better than the more rigid types that don't have the shutoff valves because it eliminates the need to make pressure washing a two person job!

This is a must-have item for people whose coaches do not have a built-in system. It stores well and always does a good job of ridding your tank of nasty residue.

Use these same steps when dumping at a dump station.
Use these same steps when dumping at a dump station. | Source

Step 5: Use Enzyme Treatments

Once a tank has been dumped and deep cleaned, treat it immediately with a biologically friendly enzyme cleaner.

Depending on the size of your tank, you normally will dump every three to five days, so you don’t need to add this product every day. However, this product is what will make future cleanings easier for you and will keep your tank odor free.

Simply toss a packet into your tank and add one gallon of water.

After doing this, the enzymes will work to eat away the sludge that accumulates on the side walls and bottom of a tank. They soften it and turn it into liquid so that it can easily flow through your plumbing system and into a sewer.

If you don't use this type of product, clumps of hardened sludge can break off and clog your tank. When this happens, you can find yourself dealing with expensive, smelly and inconvenient problems.

Hardened waste can lodge itself in your pipes and valves and can be extremely difficult to eliminate. These types of issues can become so bad that repair people will have to take parts of your system apart to fix the problems.

Thus, it is much simpler to add these products following a deep clean. Enzymes make tank cleaning much easier and faster.

There are many products on the market that can be used for this purpose, but I have found that using one such as the product manufactured by Walex that is environmentally friendly is simply the right thing to do.

These cost no more than others, but are equally effective and are just as easy to use.

For years now I have used this product and have had no problems whatsoever with clogs or odors. I used to use the liquid form, but the packets have proven just as effective and are much easier and cleaner to use.

Learn how to properly use a dump station
Learn how to properly use a dump station | Source

RV Tank Care Is Important

Now that you know what you need to have and do to keep your waste water tank clean, sanitized and sweet smelling, all you have to do is follow the above guidelines.

It may seem to be a lot of work, but once you get used to doing it, you'll find that the job gets done quickly.

You can make things easier on yourself by also taking care with what you put in your RV's toilet. You should never put

  • sanitary napkins,
  • regular toilet paper,
  • paper towels or
  • greasy foods

in them if you want to avoid problems.

Regular and proper dumping and deep cleaning of your RV sewer tanks saves you money on repair bills and make using your recreational vehicle a pleasure, so make sure you do it!

How to Thoroughly Dump and Clean an RV Blackwater Tank

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This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Questions & Answers

  • Is it safe to add Pine-Sol to the RV's toilet?

    Yes. Just make sure to add some water when using it.

  • Is it good to put enzymes in an RV's grey water tank to clean it?

    There are products made specifically for cleaning this tank, and those are the ones you should use. You can find them right on Amazon.

  • How should I keep my RV's wastewater tanks and valves during storage? Should I keep valves open?

    No. Keep a gallon of water along with some Enzyme treatment in the tank and close the valves. If you live in a cold climate, you should winterize the tank, as well.

  • How can I convince my friend that we camp with that you are supposed to use the septic hook up at an RV site that offers it?

    He probably doesn't want to use it because he doesn't want to maintain it. Don't know how you can change his mind about that except to say that using it is much more convenient and will not cause odors if you maintain it as per the directions in this article!

  • We were never told we couldn't use the toilet with the black tank valve open, but we should be sure to flush it after with a 2-gallon bucket. The fecal matter becomes a thick layer of "mortar" on the tank bottom, (if you're duped like we were), short of a pneumatic hammer, any suggestion of a product that dissolves this mortar so it will flush but not clog the pipes?

    You should always use the black tank in the closed position so that liquids mix with the waste and keep it from sticking. You only open the black tank when dumping. It is the gray water tank you keep open when parked but closed when in motion. Happy Camper makes the best product I know of for eliminating sludge. I believe you can find a link to it on the article you just read. Follow the directions carefully. Once the problem is resolved, follow the other directions for cleaning, dumping and sanitizing your RV sewer tank, and you should have no further problems. If the Happy Camper product does not get the job done, you will have to take your coach to a repair shop, have them drop the tank and scrape the mess off of the tank. This will be expensive but will be the only other way to rid yourself of the problem.

© 2012 Sondra Rochelle


Submit a Comment
  • TIMETRAVELER2 profile imageAUTHOR

    Sondra Rochelle 

    5 months ago from USA

    Bear in mind that other fluids are constantly being put into those tanks. I've always done it this way, and it's worked for 50 years, but give it a go and see if you like it better. Also, bear in mind that water is heavy.

  • profile image


    5 months ago

    Thus article contains s lot of good info ... thank you for that. I have been thinking about the 1 gallon of residual water that you suggest keeping in both tanks along with appropriate enzyme treatment. I offer the following. Assuming a couple of feet of 3" pipe between valve and tank, it will take about 3/4 of that amount to fill that pipe ... not much left in the tank to slosh about. Also not sure how well a packet of enzymes tossed in the tank will mix with the water contained in the pipe. In the case of the black water tank there is probably another 8' of pipe between upper and lower valves which could use some love too ... another 3 gallons.give or take. This does not appear to be accounted for in the article ... might want to think in terms of 5 or so gallons pre-mixed with enzymes to treat all relevant spaces for black water and 2 gallons for grey water.

  • TIMETRAVELER2 profile imageAUTHOR

    Sondra Rochelle 

    2 years ago from USA

    I would use the Spic n Span before driving and after dumping it out the next time, switch to the Enzyme treatment. You usually only use the Enzyme treatment after doing a deep clean, but you can interchange them. If given a choice, I would use the Enzyme treatment.

  • profile image


    2 years ago

    Hello! My husband and I recently purchased a brand new camper. We want to make sure that we are properly maintaining our tanks,etc. We followed the instructions for dumping and added the Spic n it ok to add the enzyme treatment at the same time? Thanks for any advice you can spare!

  • TIMETRAVELER2 profile imageAUTHOR

    Sondra Rochelle 

    3 years ago from USA

    You need to read the article again. You leave the gray tank open when you are parked at a campground and hooked up to a sewer, but in the morning, before breakfast, you close the gray tank so that you will have soapy water to use to clean out the hose through which waste matter goes to empty into the sewer connection. Your coach doesn't smell because you're confused. Your tank smells because you have not maintained it properly OR you have a clog. Dumping is not enough. At least once each week while you're using your RV you need to thoroughly backwash your tank until the contents run clear. Once you do that, you need to put a tank treatment and about a gallon of water into the tank. These treatments have enzymes in them that eat away at the waste and sludge and turn them to liquid so that you can avoid clogs. I would add here that you need to think about what you put in your Rv's toilet. You cannot use regular toilet paper. If that's what you've been doing, I would suspect a clog is your problem. I have an article about how to deal with clogs and you should read it.

  • profile image


    3 years ago

    This artical is contradicting. First video states leave gray tank open

    Second video states leave gray tank closed

    Well. Which is it. The odor in here is horrible and i came here for advice. Now I'm just as confused as ever.


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