RV Holding Tank Treatments and Cleaners: How to Choose the Right Type
The short answer
For most RV owners, an enzyme- or bacteria-based holding tank treatment is the practical default. These products break down waste and toilet paper, control odor, and are generally better tolerated by septic systems and campground dump stations than older formaldehyde-based chemicals. Pair the treatment with an occasional dedicated tank cleaner or a thorough rinse to clear buildup and keep level sensors reading accurately.
Two conditions can change that choice. If you frequently dump into a private septic system or a campground that restricts certain chemicals, check the label for septic-safe wording and avoid formaldehyde and other harsh biocides. If you camp in very hot weather or leave waste in the tank for long periods, odor control becomes the main concern, and you may want a product formulated specifically for heat or extended holding.
Treatments vs. cleaners: they do different jobs
A holding tank treatment is added routinely, usually after each dump, to manage what happens while waste sits in the tank. Its main jobs are odor control and breaking down solids and paper so they drain more completely.
A holding tank cleaner is used periodically to remove residue that treatments and normal flushing leave behind: hardened waste on tank walls, grease and soap film in gray tanks, and debris coating the level sensors. Some cleaners are meant to sit in the tank while you drive so the motion scrubs the walls; others are designed for a soak before a full rinse. Many owners use both: a treatment for everyday use and a cleaner a few times a season or before storage.
Main types of holding tank chemicals
Type | How it works | Strengths | Trade-offs; Enzyme-based | Enzymes break down waste and paper | Generally septic-friendly; reduces solids | Odor control can vary by formula and conditions; Bacteria-based (biological) | Live bacteria digest waste | Strong breakdown of solids and paper; septic-friendly | Can be weakened by harsh chemicals or bleach in the tank; Nitrate- or oxygen-based | Encourages odor-free breakdown chemistry | Often good odor control; usually free of formaldehyde | Performance depends on the specific formula; Formaldehyde or similar biocides | Kills bacteria to stop odor | Strong, fast odor suppression | Can harm septic systems; restricted at some dump sites; does little to break down solids; Deodorizer-only (fragrance) | Masks smell | Inexpensive and simple | Does not address the source of odor or buildup
Some products blend several approaches, such as enzymes plus an odor neutralizer. Labels do not always state the active chemistry clearly, so look for terms like enzyme, bacteria, biological, nitrate, formaldehyde-free and septic-safe.
Where Digest-It and similar products fit
Digest-It is a commonly searched brand of RV holding tank treatment and is marketed in the biological, waste-digesting category rather than as a chemical biocide. If you are comparing it with other products, judge it by the same criteria as any treatment: the active type stated on the current label, the format you prefer, the dosing for your tank size, and whether it is labeled safe for septic systems. Formulations and product lines can change, so read the packaging of the version you are buying rather than relying on older reviews.
What to check before buying
Active chemistry: enzyme, bacterial, nitrate/oxygen, or formaldehyde. This decides how well the product breaks down waste versus simply suppressing odor. Septic and dump-station compatibility: look for septic-safe or formaldehyde-free labeling if you use private septic systems, rural campgrounds or sites with posted restrictions. Black tank, gray tank or both: some treatments are formulated only for black tanks. Gray tanks benefit from products that cut grease and soap film. Format: drop-in pods are easy to dose and store; liquids are flexible for different tank sizes; powders are compact but need water to dissolve properly. Dosing per tank capacity: check how much the label calls for relative to your tank size, and calculate cost per dose rather than comparing package prices. Climate suitability: hot weather speeds up odor; some products are marketed specifically for high temperatures. Toilet paper performance: if clogs or pyramid-shaped piles under the toilet are a problem, prioritize products that emphasize paper and solids breakdown. Sensor and seal friendliness: avoid products that leave heavy residue or rely on harsh solvents that could affect rubber seals and valves; the label should state it is safe for RV plumbing.
Choosing a holding tank cleaner
Pick a cleaner based on the problem you are seeing. Level sensors that show the tank as partly full right after dumping usually point to residue or paper stuck on the sensor area, and a cleaner aimed at sensor buildup is the logical choice. Persistent odor after dumping suggests waste coating the walls, which calls for a soaking or agitation-type cleaner followed by a thorough rinse. In gray tanks, slow drains and sour smells often come from grease and food particles, so a degreasing cleaner suited to gray water is more effective than a black tank treatment.
Use products labeled for RV holding tanks rather than general household cleaners. Strong household chemicals such as bleach can be hard on seals and valves if used carelessly, and they kill the beneficial bacteria that biological treatments depend on. If you do use a sanitizing product, rinse well before adding a biological treatment again.
Habits matter as much as the product
No treatment can make up for too little water in the black tank. Adding water to the tank after each dump, before the treatment goes in, gives waste something to break down in and keeps solids from drying onto the bottom. Using enough water with each flush helps the same way.
Keep the black tank valve closed until you dump, so liquids stay in the tank to carry solids out. Dump when the tank is reasonably full rather than draining it in small amounts, so the volume of water helps flush solids. Dump the black tank first, then the gray tank, so gray water helps rinse the hose. Use a tank flush system or a rinse wand if your RV supports one, especially before storage. Use toilet paper that breaks down easily if you have recurring clogs.
A sensible next step
If you mostly use full-hookup campgrounds and dump stations, start with a formaldehyde-free enzyme or bacterial treatment in the format you find easiest to dose, and add a holding tank cleaner when sensors misread or odors linger after dumping. If you often dump into septic systems or camp where chemicals are restricted, make septic-safe labeling a firm requirement. If heat and long holding times are your main challenge, look for a treatment marketed specifically for odor control in those conditions, and stay consistent with water use and dumping habits.
