Your Cart is Empty
Black Tank · Gray Tank · Sensors · Drains
RV Black Tank & Holding Tank Treatment
Bio-Pure RV Black Tank & Drain is a holding tank treatment: proprietary microbes, fed by Deproteinized Whey (DPW), break down organic matter, bottom solids, scum and toilet paper in black and gray tanks — eliminating odors at the source instead of covering them up.
- Breaks down waste, solids and scum
- Eliminates odors at the source
- For black tanks, gray tanks, sensors and drains
- Safe for all pipes
A liquid with a citrus-ginger scent, or a super-concentrated powder. Made in the USA.
100% satisfaction guaranteed
Made in the USA and backed by 30+ years of development and testing.
Choose Yours
Liquid or powder, same job
Treatment counts depend on your black tank: each container treats a 20–50 gallon tank the number of times shown, or a 55–88 gallon tank half as many.
Liquid — 32 oz, two strengths
Citrus-ginger scent. The bottle has a built-in measuring chamber marked in fluid ounces.
Concentrate
32 oz · 300 million CFU/oz
16 treatments for a 20–50 gal tank
or 8 for a 55–88 gal tank
The everyday strength.
Super Concentrate
32 oz · 600 million CFU/oz
32 treatments for a 20–50 gal tank
or 16 for a 55–88 gal tank
Twice the treatments from the same bottle.
Super-Concentrated Powder
Dosed by the scoop. The 14 oz and 48 oz cost less per treatment than either liquid — about $0.75–$0.88, against $0.94–$1.16.
4 oz
2 billion CFU/oz
16 treatments for a 20–50 gal tank
or 8 for a 55–88 gal tank
Try the powder.
14 oz
2 billion CFU/oz
56 treatments for a 20–50 gal tank
or 28 for a 55–88 gal tank
More than three times the 4 oz.
48 oz
2 billion CFU/oz
192 treatments for a 20–50 gal tank
or 96 for a 55–88 gal tank
The lowest cost per treatment.
Liquid or Powder?
Pick the format that suits how you travel
Choose the liquid if…
- You want a built-in measuring chamber
- You like the citrus-ginger scent
- You'd rather pour than scoop
Choose the powder if…
- You want the lowest cost per treatment (14 oz and 48 oz)
- You travel full-time or treat several rigs
- You'd rather dose by the scoop
How To Use It
Three ways to use one product
Routine black tank
Add a dose for every 50 gallons of tank capacity directly to the toilet, and flush.
Gray tank & drains
Every 2–3 months, mix a dose with warm water and pour it into your shower, sink and laundry drains. Leave overnight.
Soak & clean-out
A larger dose that sits in a part-filled tank to break down built-up solids. Steps below.
Black tank clean-out
Drain the tank
Empty the black tank as usual.
Refill it halfway
Fill the tank to about 50% with water.
Add the clean-out dose
Pour it directly into the toilet and flush.
Let it sit 24–72 hours
Give the microbes time to work on the buildup.
Drain again
Empty the tank to flush out what was broken down.
Exact doses differ by product and strength — they're on each label and product page.
What's Inside
Proprietary, task-oriented microbes
Microbes that break down organic waste and reduce ammonia-, nitrate- and hydrogen-sulfide-forming bacteria and their odors. Counts per ounce, from the labels:
300M
CFU/oz — Liquid Concentrate
600M
CFU/oz — Liquid Super Concentrate
2B
CFU/oz — Powder
Safe for animals, humans, plants and pipes, and environmentally safe. All natural and biodegradable.
The Bio-Pure Difference
What is DPW?
Deproteinized Whey (DPW) is a built-in nutrient source for the microbes. RV tanks see intermittent use and low oxygen, which makes it hard for ordinary bacteria to get going — DPW gives them what they need to get to work.
Faster activation
DPW acts as a micronutrient starter, jumpstarting the microbes so they start digesting waste sooner.
Built for harsh tanks
Intermittent use and low oxygen hold ordinary bacteria back. DPW gives Bio-Pure's microbes a head start in those conditions.
Breaks down biofilm
The microbes digest waste and the sticky biofilm on tank walls that traps odor and throws off sensor readings.
Common Questions
Before you buy
What's the difference between Concentrate and Super Concentrate?
Both are 32 oz bottles. Super Concentrate has twice the microbes per ounce (600 million CFU against 300 million), its dose is half the size, and the bottle gives twice the treatments: 32 against 16 for a 20–50 gallon tank.
How much do I use?
One dose per 50 gallons of black tank capacity: 2 oz of Concentrate, 1 oz of Super Concentrate, or one ¼ oz scoop of powder. A clean-out uses twice that.
My tank is bigger than 50 gallons.
Scale the dose to the tank. The labels give counts for a 20–50 gallon tank and a 55–88 gallon tank — a larger tank gets half as many treatments per container.
Is it safe for my RV's plumbing?
Yes. The label says it's safe for all pipes, and the directions list it as safe for animals, humans, plants and pipes, and environmentally safe.
What is DPW?
Deproteinized Whey — a nutrient source for the microbes, so they activate faster and keep working in the tank. Every RV Black Tank & Drain product contains it.
Can I use it on a boat?
Yes — the directions list RV and boat/marine septic and drains.
Break it down. Keep the odor out.
Bio-Pure RV Black Tank & Drain — for black tanks, gray tanks, sensors and drains.
Why RV holding tank odors start in the tank
The smell in an RV does not start at the toilet; it starts in the black tank below it, where waste sits and breaks down badly between dumps. Sprays and bowl deodorizers cover that smell. Bio-Pure's microbes digest the waste, bottom solids and scum that cause it, so the odor is eliminated at the source.
How much to use, by tank size
| Product | Per 50 gal of tank | Clean-out |
|---|---|---|
| Concentrate liquid | 2 oz | 4 oz |
| Super Concentrate liquid | 1 oz | 2 oz |
| Concentrate powder | 1 scoop (¼ oz) | 2 scoops |
Scale the dose to the tank: the labels count treatments for a 20–50 gallon tank and for a 55–88 gallon tank. For a clean-out: drain, refill halfway, dose, wait 24–72 hours and drain.
Formaldehyde-free, and safe for seals, sensors and septic
Bio-Pure treats an RV holding tank with live microbes rather than formaldehyde. It is safe for all pipes, and the directions list it as safe for animals, humans, plants and pipes, environmentally safe, all natural and biodegradable — including at a dump station feeding a septic system.
Keeping tank sensors reading right
Black tank sensors read "full" when waste and film cling to them. Because the microbes digest that buildup on the tank walls and sensors along with the rest of the waste, the readings stay honest for longer.
Black tank, gray tank and drains
Use it in the black tank, in the gray tank, and in the shower, sink and laundry drains that feed it. Gray water goes off just as fast as black water in warm weather, and the same biology handles both.
Boondocking, long trips and storage
Dry camping means tanks sit longer between dumps, which is exactly when odor and solids build up. A dose at the start of a stretch keeps the waste digesting while you are off grid, and a clean-out dose before storage leaves the tank in better shape when you come back to it.
Frequently asked questions
How much do I use in my holding tank?
One dose per 50 gallons of tank capacity: 2 oz of Concentrate, 1 oz of Super Concentrate, or one 1/4 oz scoop of powder. A clean-out uses twice that.
Does it break down toilet paper?
Yes. The microbes digest organic waste, bottom solids, scum and toilet paper in the tank.
Will it help my tank sensors read correctly?
Sensors misread when waste and film stick to them. Bio-Pure digests that buildup on the tank walls and sensors as part of breaking down the waste.
Is it formaldehyde-free?
Yes. Bio-Pure works by live microbes, not formaldehyde. The directions list it as safe for animals, humans, plants and pipes, environmentally safe, all natural and biodegradable.
Can I use it in the gray tank?
Yes. The same treatment works in gray tanks and the drains that feed them, as well as the black tank.
Can I use it on a boat?
Yes. The directions cover RV and boat/marine septic and drains.