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

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

Cleaning out your RV's sewer tank doesn't have to be hard!

Cleaning out your RV's sewer tank doesn't have to be hard!

How to Clean Your RV's Sewer Tank in 5 Steps

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.

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

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

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

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

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

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

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

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

Answer: 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.

Question: 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?

Answer: 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.

Question: When you do a deep clean pressure wash to an RV's black waste holding tank with a wand, do you turn off the water to your toilet then use the wand?

Answer: No. You don't need to do this because you have already opened the hose that connects the tank to the sewer so any fluids that go into the tank from either end will exit through the hose.

Question: 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?

Answer: 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!

Question: We bought our camper used, but we do not use our bathroom. It didn't smell when we bought it, but we prepared it for travel. The first week we had it at the lake it started smelling. Why?

Answer: If you remove the fluids from a sewer tank, bacteria will grow in it and start to smell. You need to clean and sanitize your tank as per the directions in the article and always make sure there are some enzyme chemicals and water in it, even if you don't use it. That should get rid of the odor.

Question: I just bought and sanitized a used 2015 Four Winds. After filling the tank, the gray water and black water tanks show only 3/4 full. Why is this?

Answer: Each tank is separate, so filling one should not affect the others. It is highly likely that your sensors are not working properly, so what you are seeing may be incorrect information.

Question: Is there a company I can call to dump my RV's sewer tank for me?

Answer: Any RV repair shop that has a dump station can do this for you, but you'd have to be calling them constantly because this job needs to be done at least once weekly when your RV is being used. Not a practical idea and, frankly, it's very easy to do yourself.

Question: My 23-year-old son just bought a travel trailer and will live full-time in a campground. Does he still need to empty tanks like this, or is this just for when you travel around or vacation?

Answer: Unless he is never going to use the toilet at all, he'll have to follow this procedure.

Question: What would cause sewage to leak out from under the raised platform the toilet sits on in my RV?

Answer: A leak in the plumbing that attaches the toilet to the tank (a bad one most likely).

Question: This information is useful for a bigger RV, but my RV is a mini camper with only one dumping line and one shower/sink drain, what is best for me?

Answer: I would follow the directions for cleaning the tank and then make sure to rinse it thoroughly after dumping. Also, keep the line closed until you are ready to dump each time. Clearly, you'll have to dump more often, but if you do not sanitize and clean the tank regularly, you're going to have odor problems.

Question: Is it safe to put the bleach and enzymes used to deep clean into a home septic system?

Answer: This is a question for your plumber to answer. There are treatments that are specifically made for home septic systems, and I would think those should be the ones to use.

© 2012 Sondra Rochelle