Guide: Best RV Holding Tank Treatments for Black & Gray Tanks

Nobody likes the bad smell of a black or gray tank emanating into their RV. That’s why RV product manufacturers come up with all sorts of black tank treatments and products to clean and sanitize your holding tanks. But while there are a lot of options, some more popular than others, there are only a few holding tank treatments that really work to treat and clean your black tank and gray tank – and they’re not the products you’d guess.

If you go to Camping World or any RV parts store, you’ll see formaldehyde-filled tank treatments advertised to you left and right. You’ll even receive free boxes and bottles black tank cleaners when you buy a new RV.

I’m sorry to tell you – those formaldehyde-filled treatments don’t really work. They just mask the smell! And the masking only works until it gets too hot. Eventually the smell of your black tank will come through because your tanks aren’t really getting cleaned, just deodorized.

So what black tank treatments SHOULD you use?

I’ve covered my favorites below.

The Best RV Holding Tank Treatments

1. Happy Camper: The Best Black Tank Treatment

Happy Campers RV Holding Tank Treatment - 64 treatments

$55.45  in stock
as of April 18, 2024 1:55 am

When I first bought a used RV, I had to drive with the windows rolled down, the smell of my tanks was so bad. Funnily enough, I’m pretty sure the smell was my gray tank. That’s because I didn’t know better and was only using a formaldehyde based treatment.

Happy Camper can treat both your black and gray holding tanks, and uses enzymes to work on the contents of your tanks. Ever since switching to this, I buy tank treatments less often (one canister goes a LONG way) and never smell my tanks. It’s also said to be septic-safe.

2. RV Digest-It: Highly Recommended

Unique RV Digest-It Black Tank Treatment - Concentrated Drop-in Pod Toilet Treatment - Eliminates Odors, Breaks Down Waste (20 Treatments) - 41G-4

 out of stock
as of April 18, 2024 1:55 am

RV Digest-It has created both a regular tank treatment and a higher powered tank cleaner. This formula is also based off of enzymes. It’s more popular in in-person RV stores than Happy Camper is, but I’ve come to believe that’s because it’s more profitable or a bigger company with better distribution – not because it works better. I have used this at one point and it worked fine. Definitely better than the formaldehyde treatments. 

3. Porta-Pak and TST: Most Popular, Not Recommended

Walex Porta-Pak RV Black Holding Tank Deodorizer Drop-Ins, Fresh Scent, (Pack of 10)

 in stock
20 new from $10.44
Free shipping
as of April 18, 2024 1:55 am

Camco TST MAX Ocean Scent RV Drop-Ins - Eliminates Odors and Aids in Breaking Down Holding Tank Waste - Includes 30 per Bucket (41615)

 in stock
36 new from $20.82
Free shipping
as of April 18, 2024 1:55 am

The Porta-Paks and scented Camco TST drop-in treatments are simply not recommended. You can use them if you’re in a pinch or if you’ll be emptying your tanks very frequently, but long term or in heat, they don’t seem to stand up to smells or truly digest any of your waste. With formaldehyde, I’m also not sure if they’re septic-safe.

Any “RV blog” that recommends these as the top choice has clearly not had any extended experience RVing – or emptying their tanks – or smelling their black tank. 

4. DIY Method 1: “The Geo Method”

You may have heard of “the geo method” which is where you mix fabric softener in your black tank. This is something I have yet to try. Have you?

5. DIY Method 2: Ice in the tanks

Some RVers recommend pouring a bag of ice into their black tank after each flush and then driving around, which is said to help “scrape” the insides of your black tank while driving to help clean the tank and its sensors.

Black Tank Questions

How often should you empty your tanks?

This is a common question asked by those new to the RV world. If you’re out boondocking, you should empty your tanks as often as necessary, because you’ll likely be going to the dump station once the holding tanks are full. If you’re staying in an RV park, you should keep your tank valves closed and only empty them every few days at most, or as needed if more. This is because if you leave your tank valves open, you can get what’s known as a poo pyramind since the most liquid contents of your black tank will drain first. You need both the liquid and the solids contained together for gravity to work its magic and clean your tanks thoroughly.

Is my tank treatment septic-safe?

You should check with the specific tank treatment you’re using as well as your preferred septic company. I have heard formeldahyde is not good for septic tanks, but I am an RVer, not a septic expert.

Should I treat my gray holding tank?

If your gray tank smells, yes you should treat it. I treat mine every so often with Happy Camper. I once had a pair of RVing friends who thought there was something wrong with their tanks because it smelled so bad they were sure their vent was broken, but I treated it with some of my Happy Camper, and the problem was gone.

What if my holding tanks still smell after treatment?

If your holding tanks still smell after dumping, cleaning, and treating them, you may need to check your vents or your RV air-admittance valve. A faulty valve in your pipes will cause your under-sink areas to stink because they will be letting gray tank air back into your living space. They go bad every so often.

Now that we’ve covered some of the best RV black tank treatments and black tank questions, what’s your favorite cleaner or treatment, and how often do you use it? Do tell in the comments!

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