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How to Get Rid of RV Holding Tank Smells

I am an RV enthusiast with more than 50 years of experience owning, driving, traveling and living in recreational vehicles.

For people who own RVs, it's important to learn how to get rid of the noxious odors that come from their coach's holding tanks.

Generally, gray and fresh water tank odors can be eliminated easily simply by following the guidelines in How to Care for Your RV's Fresh Water Tank..

However, those that come from black water tanks and plumbing problems are more complicated because normal maintenance doesn't address all odor causing issues.

This article points out these problems and shows you the best ways of dealing with them.

Tips to help RVers get rid of nasty odors that hide in their coaches.

Tips to help RVers get rid of nasty odors that hide in their coaches.

Don't Trust Your Tank Monitors

Tank monitors are not always reliable, especially on older motor homes and campers. Once they stop functioning, it is easy for waste matter to build up and make RVs smell.

The reason they stop working is that sludge builds up on them over time and is very difficult, if not impossible, to remove.

So, if you have a coach whose monitors work, your best protection is to perform normal maintenance as described in How to Dump, Clean and Maintain Your RV’s Blackwater Tank.

If your monitors do not work, you can eliminate normal tank odors simply by dumping often, deep cleaning regularly and performing daily maintenance as noted in the above article.

Avoid Clogging Your RV's Toilet

RV plumbing systems clog easily. It is always a mistake to put anything into toilets except biodegradable toilet paper.

Never try to flush tampons, paper towels, sponges or other inappropriate items down an RV toilet, because they cause expensive and inconvenient problems.

Don't use regular household toilet paper either. it will clog your tank as fast as those inappropriate items I just mentioned. Biodegradable paper is more expensive but can save you thousands of dollars in repairs.

My husband and I never travel without biodegradable toilet paper because we’ve learned the hard way (as you will see shortly) about the problems that come from trying to cut corners by using regular types of toilet paper!

We use the Coleman brand because it dissolves quickly, does a good job and is reasonably priced.

Know Your Tank Capacities

Few people realize that RV tanks vary in size from one coach to another. Never assume that a larger travel unit has bigger tanks than a smaller one, because this is not always true.

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The manuals from your coach’s manufacturer will tell you the capacity of each tank. If you do not have them, you can find the information you seek on the internet or by contacting the parts department of your local RV dealer.

The size of your tank lets you know how often you must dump. If you know this information, you will be able to minimize or eradicate sewer tank odors quickly.

Know Your RV’s Fill Methods

RV sewer tanks fill either from the toilet, shower, bathroom sink or some combination of the three.

The more inflow sources there are, the more quickly the reservoirs fill and the more often you need to dump. If you wait to long to empty your sewer tank, not only will your coach start to smell, but you may cause flooding.

Knowing the ways in which your sewer tank fills and using that information to guide your dumping program is important in helping you to keep your coach smelling good.

Find the Causes of Ongoing Odors

Under normal circumstances, if you do a good job of cleaning, emptying and maintaining your tank, you should never have odors in your coach.

If you do, it is possible you have a more complicated issue such as leaking valves, clogs, a poor plumbing design, or even some broken sewer pipes

  • If you are handy, you may be able to address and fix such problems yourself.
  • If not, you may require the help of an RV mechanic.
If your tank is clean but still smells, it's time to investigate other issues that may be causing odors.

If your tank is clean but still smells, it's time to investigate other issues that may be causing odors.

Odors That Persist Even After Cleaning

Under normal circumstances, if you follow the directions in How to Dump, Clean and Maintain Your RV‘s Blackwater Tank, you should never smell tank odors in your coach.

If you do, it is possible you have a more complicated issue such as:

  • leaking valves
  • clogs
  • poor plumbing design
  • broken sewer pipes

If you are handy, you may be able to address and fix such problems yourself.
If not, you may require the help of an RV mechanic.

Before you seek outside help, it would be a good idea to try a product such as Extreme Tank Cleaner that can help you to know if your problem is caused by hardened deposits or one of the above issues.

This product can decimate sludge and eliminate the clogs that form when pieces of it stuck to tank walls break off and fall into sewer pipes.

I have not used it personally, but people who have used itsay that it is very effective.

It is expensive and should only be used as a last resort before researching other sources of sewer odors or calling in an RV repair man.

Users say the secret is to use it exactly as per the manufacturer's directions.

Leaking Valves

Sometimes when there is a valve leak, the odors seep up into the walls of your bathroom..

So, even after you have deep-cleaned the tank, your coach still smells.

it is hard to figure out where the smell is coming from, but the most obvious culprit is a leaking valve.

Here are some fixes that may deal with this problem.

  • Install an RV cyclone sewer plumbing vent that functions in the same way as the one you use in your attic. It will suck those smells out of your RV and exit them through the vents. (My husband and I did this when we were having odor issues, and it was one of the things that helped us to completely eliminate those smells).
  • Repair or replace a damaged sewer vent.

It is possible that you may even have to do both, but once you do, your coach should no longer smell. You can believe me when I say that doing these two things is worth every penny!

Broken Sewer Pipes

Sometimes, due to sloppy construction methods or road vibration, sewer pipes can develop cracks or even break off.

When this happens, tank odors fill your coach, but you cannot find their cause.

  • If you are handy, you may be able to remove part of the wall board behind your toilet so that you can see if a pipe has cracked or is broken and then fix it.
  • If not, you will need to have a repair person do this job for you.


As noted above, waste water tanks can easily become clogged if they are abused or improperly maintained.

How to Clear an RV Toilet Clog shows you how to repair a stopped-up system yourself, but doing this is a dirty, messy job that does not always work.

You only have to try to clear a clog yourself once to realize you don't want to do it again, and you had better make some changes about what you put into your toilet.

It's important to know how your RV's plumbing system is structured.

It's important to know how your RV's plumbing system is structured.

Poor Plumbing Design

In some motor homes, the very structure of the plumbing system can be a problem.

For example, the diagrams of one brand show that it has a 45 degree turn in the pipes. Thus, heavy bowel movements or using too much toilet paper at one time can clog the system.

Furthermore, sludge build up can sometimes break off and get stuck in the valves and damage them.

Check your specs to make sure this is not your situation. If it is, take great care with what you put in your toilet!

Sewer Tank Damage

Sewer tanks crack due to overloading with liquids, accidents that cause flying debris to forcefully hit them or normal aging.

You can generally avoid the first two problems by

  • never allowing the reservoir to completely fill before draining it
  • making sure that your tires are always properly inflated and
  • taking great care when driving.

If your coach is old, there's not much you can do about it‘s age, other than to inspect it regularly for damage and make repairs where necessary.

Eliminating RV Tank Smells Takes Effort

It isn’t always easy to get rid of noxious RV odors, but with patience and research and some elbow grease you can do it.

Normally regular maintenance will keep your holding tanks in good condition, but if not, it may be time to take more serious action.

Good Luck!

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: We bought our travel trailer one month ago. Our second black tank filled up to the top that the toilet. We called the RV repairman. He informed us of an extra valve had to be opened. Now that tank really stinks. We have cleaned it three times. Do you have any suggestions?

Answer: You need to read this article right now... It will explain everything to you. You have three (for waste), grey for soapy water and fresh for drinking and bathing water. You have to empty the grey and black regularly, and this article shows you how to do it. Your tank smells because you have left the black water tank open. It should be kept closed until you empty...which should be at least every other day while you're using your unit. You should also use the recommended chemicals to help keep it clean, and do not use regular toilet paper. If you do this, it will clog, and you'll have really big and expensive problems. Read the article and follow the directions in it and you'll be OK.

© 2016 Sondra Rochelle

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