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Preventing Clogs In Your RV Holding Tank

February 24, 2020

Avoiding and preventing clogs and backups inside my camper RV motorhome trailer fifth wheel black water toilet holding tank

There are a number of ways that clogs can form in your RV black tank, but the most common mistake is that people forget to, or aren't in the habit of, following a few simple steps to keep their RV clog free. The following simple tips will save you hours of valuable time and potentially hundreds of dollars in service fees and man hours!

How To Prevent Clogs in Your RV Black Water Tank

We get calls all the time from customers asking about this one simple issue. What it really comes down to is habits—making sure that you’re following the correct steps to ensure that you don't get clogs. By far, the biggest mistake people make is leaving their black tank valve open. This alone is the culprit for 50% of clog and odor issues. The other 50% comes from not using enough water and/or using an RV tank chemical that is counter-productive.

When you leave your black tank valve open, any liquid inside your holding tank drains out and all that you're left with is the solid waste. While it was in your tank, that liquid was helping to break down the waste and cover the odors. Without the liquid, pyramid plugs are common. In fact, this is how most pyramid plugs are formed. 

What is a pyramid plug and how do they happen in my RV camper trailer motorhome black water toilet tank

For those of you who are unaware, a pyramid plug is literally a pile of poop that has accumulated inside your tank! Without the right tools, a pyramid plug can be one of the most difficult issues to fix. Many people don't realize that their black water holding tank is most likely flat across the bottom. This means that if there isn't a large amount of water for your poop and toilet paper to fall into, it simply lands on the bottom of the tank, eventually building up into a pyramid. Graphic, we know! But the reality is that this is a huge problem for far too many RVers who have been improperly instructed to leave their black tank valve open. The simple takeaway: keep your black tank valve closed! 

You might be one of those campers who habitually leaves your black tank valve open and you've never experienced any problems. First, you're lucky! Second, our experience helping hundreds of frustrated RVers deal with clogs tells us that you're sitting on a ticking time bomb! It's probably only a matter of when you finally experience a clog, pyramid plug, or back-up. We strongly recommend that you change this habit while you're still ahead!

Basic Techniques For Avoiding Clogs In Your RV Black Water Holding Tank

(note: make sure you read the full rules at the bottom of this blog post)

  1. Close your black tank valve until you need to dump!
  2. Use a bacteria-based waste digester like RV Digest-It Holding Tank Treatment (more on this product later).
  3. Use plenty of water in your RV toilet. This helps to control odors and keep waste from re-solidifying or caking to the inside of your tank.
  4. Never use any bleach-based or chemical toilet bowl cleaners. These products will kill the beneficial, waste-digesting bacteria inside your tank and can lead to clogs as well as damage your toilet’s seals and valves.
  5. Keep your tank temperatures regulated. RV Digest-It is the best bacteria-based holding tank treatment for preventing clogs—hands down. However, all bacteria toilet treatment products have an effective temperature range of roughly 45° F to 85° F. On either extreme end of that spectrum, all brands of bacteria-based holding tank treatments will struggle. We recommend insulating or heating your tank in cold weather and increasing water usage + higher dosage of bacteria treatments in hot weather.

These are the basic steps, but let's get into this a little more.

Bacteria Based RV Holding Tank Treatments

Here’s why bacteria-based RV toilet products are your best choice for preventing clogs: they completely break down and liquefy solid waste. In essence, bacterial-based products leave nothing behind to clog your tank in the first place. If you are curious what that waste breakdown process looks like and why Unique products out-perform all other bacteria treatments on the market, click here. Many common RV tank treatments on the market today are strictly meant for treating odors and not waste. In fact, many treatment products even have ingredients (e.g., formaldehyde) that actually preserve solid waste by encapsulating the poop in your holding tank! Remember high school science class? That fetal pig you dissected was soaked in formaldehyde to preserve it! This clearly defeats the purpose of having a tank cleaner in the first place, especially since the goal is to digest the solids inside your tank and prevent clogs and odors.

 Want to learn more about the different types of tank treatments and toilet chemicals? Click here.

When it comes to using bacteria-based holding tank treatments like RV Digest-It, there are a few tricks that you will need to know. Regulating your tank temperatures and staying away from caustic toilet cleaners are the two big ones. Although they can survive high heat and deep cold, bacteria are sensitive organisms, and it significantly affects their efficiency. To control this, heating or insulating your holding tank during winter months, increasing your treatment amount, and using extra water with each flush during summer months is crucial.

Note: Odors in your tank are caused by anaerobic bacteria, which come from your stomach. Anaerobic bacteria are different from aerobic bacteria—like you find in RV Digest-It. Anaerobic bacteria are unfortunately the more resilient of the two bacteria types. As a result, when you add chemicals to your tanks (in the form of toilet cleaners, deodorizers, or toilet treatments), you’ll most likely kill off all of the good aerobic bacteria first, since they tend to be less resilient, and leave only the bad anaerobic bacteria behind to make the smells in your RV unbearable. Simply put—don't do it! Avoid chemicals of all types if you truly want an odor-free RV experience! If you are interested, you can read more about this topic here.

Lucky for you, plenty of water—combined with RV Digest-It—is a match made in heaven! Ample water allows the bacteria in our product to reach all the waste that’s inside your tank. That way, instead of just dealing with clogs and odors as they come (and they will), you can just cut out the middle man and prevent them from being an issue in the first place. On top of helping prevent clogs, using enough water will keep those nasty tank odors under water and under control.

Permanently Avoid Clogs and Odors By Following These Rules

    • Flush your tank. After you dump your tank, flush or rinse it well. The longer you rinse your tank, the better. This will help to clean out the nooks and crannies of the tank (we recommend 20-30 minutes of rinsing when possible).
    • Always keep your black tank valve closed except when dumping your tank.
    • Charge your tank before treating. Before treating your black water holding tank with a high-quality treatment, close your black tank valve and "charge" your holding tank by filling it with 3-5 gallons of water (usually, about 1 minute of holding down your toilet flush-pedal).
    • Use a high-quality RV toilet treatment. Treat your tank with a high-quality, bacterial-based treatment product. We recommend RV Digest-It Holding Tank Treatment.
    • Add ample amounts of water each time you flush the toilet. We recommend that you hold down your flush pedal for 10 full seconds during each flush. This will ensure two important things:
  1. That you maintain an ample amount of water inside your tank. If the waste inside your tank is allowed to dry up, you will experience increased clogs and odors.
  2. That no solid waste ends up above the water line. When fecal matter is exposed to air (i.e., isn't covered by water), it’s extremely smelly. Furthermore, the active bacteria and enzymes in RV Digest-It move by way of water, and if the waste is above the water line, these cleaners can’t reach the waste. As a result, the bacteria and enzymes won’t be able to break down the waste or eliminate the anaerobic bacteria that are creating those foul smells!
  • Add water to your toilet bowl before you use the toilet. Before your go #2, always add ample water to the bowl.
  • Keep water in your toilet bowl. Always keep your toilet bowl half-full of water. This water barrier will prevent residual tank gasses and odors from escaping your RV's black tank. Not only do these gasses smell, but they are quite unhealthy to breathe.

Preventing clogs is much easier than trying to unclog a backed-up holding tank. Not only is it expensive to hire a service to clean out your compacted tank, but it's frustrating and difficult if you don't have access to restroom facilities—or if you simply don't like using public toilets. After all, isn't having your own bathroom one of the luxuries of owning a camper or trailer?!


Preventing clogs is actually quite easy and painless. With a few simple adjustments to your holding tank habits, you can ensure a clog free RV in no time! This blog fits into the bigger picture of overall holding tank care and maintenance, part of a step by step guide we call The Unique Method. To learn how to maintain both your gray and black tanks and get the most out of your RV travels learn how to use The Unique Method.

If you do ever deal with a nasty clog, no worries! We’ve got your back! Unique Holding Tank Cleaner is a perfect, effective, and safe solution that will save you hundreds in service fees and charges. Plus, it comes with a satisfaction guarantee, so if it doesn't work, it’s on us! We hope this article has helped answer your tank clog questions! Feel free to email us if we missed anything or if you need help. We're always here for you!

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