black tank chemicals

Lots of water, fill before you dump, dump often and add four or so gallons after dumping. No chemicals needed.

I live in hot FL. If you leave raw sewage in the tank for a few days between dumping/flushing, it will produce a very foul odor! Unlike a septic tank, this is not an anaerobic environment. Folks up North have less issue most of the year due to the milder temperatures.

I've tried many different ones on the market. One works better than all the rest. Thetford Aqua-Kem.


*Deodorizer - Formulated to work in any weather condition, Aqua-Kem is packing the most powerful odor control available on the market.

*Waste liquefier - Clogging is no longer an issue, as Aqua-Kem breaks down solid materials, liquifying waste and toilet tissue fast and efficient.

*Detergent - The third component of the 3-in-1 formula is the detergent, which cleans the tank walls and drain lines, maintaining the tank and lines in top shape.

*SAFETY: The 100% biodegradable waste holding tank treatment is safe even for septic tanks.

*FUNCTIONALITY: Formulated as a 3-in-1 product, the formula holds a powerful deodorant, a waste liquefier, and detergent, eliminating odors, breaking down waste and cleaning the tank.

I've been using this product since the late 80s. I've dumped my tank into our septic tank on many occasions. Zero issues. No stink from the RV. Try anything else first if you wish. Just keep this one in mind if they don't work for you.

$21 for a gallon on Amazon. https://amzn.to/2Hc8foF

We use the Aqua-Kem powder because the wife likes the smell. They're all about the same IMO. If you have a serious odor problem, your tank is not getting adequately rinsed out when you dump.

If you’re getting black tank oder then there is a venting or seal issue. If you have a black tank flush system the oder may emanate from a poorly sealing back flow valve, most likely somewhere in the bathroom vanity cabinet. I use Happy Campers to appease the DW, and to perhaps help with the breakdown of TP and solids.

Water alone is not going to keep a tank full of sewage from smelling.
And it's just that; a tank. So when you open a hole in the top of it (like flushing) there's nothing to keep gasses from rising up out of the hole. There's no reason those gasses are going to choose to go up the vent rather than the toilet opening.
25 cents worth of chems (or less, I bought a lifetime supply at a garage sale for $2) and there is no smell.

When I bought my (new to me) used 1999 Class A in 2011, the previous owner had several boxes of older Thetford Blue packets under the bathroom sink. The boxes clearly said "contains formaldehyde" on the label. From several years of college level chemistry/biology lab experience, I know what that smells like and I'm sure they did. The smell reminds me of the commercial porta-potty smell along with the blue dye which is intended for industrial strength odor applications.

I used the PO's supply up then discontinued using odor control chemicals because the RV park where I was staying asked me not to. They said it wreaked havoc with their septic system. Since then, I've used only water and sometimes some fairly clean used dishwater with liberal amounts of dish washing soap already in it. As long as I dump/flush the tanks every 2-3 weeks, no odor problems at all.

Chum lee

ScottG wrote:
Water alone is not going to keep a tank full of sewage from smelling.
And it's just that; a tank. So when you open a hole in the top of it (like flushing) there's nothing to keep gasses from rising up out of the hole. There's no reason those gasses are going to choose to go up the vent rather than the toilet opening.
25 cents worth of chems (or less, I bought a lifetime supply at a garage sale for $2) and there is no smell.

Disagree. Water only for the past 7 years. Flush the tanks, use plenty of water each time I flush and always keep a few inches of water in the tank at a minimum. No smell.

way2roll wrote:

ScottG wrote:
Water alone is not going to keep a tank full of sewage from smelling.
And it's just that; a tank. So when you open a hole in the top of it (like flushing) there's nothing to keep gasses from rising up out of the hole. There's no reason those gasses are going to choose to go up the vent rather than the toilet opening.
25 cents worth of chems (or less, I bought a lifetime supply at a garage sale for $2) and there is no smell.

Disagree. Water only for the past 7 years. Flush the tanks, use plenty of water each time I flush and always keep a few inches of water in the tank at a minimum. No smell.

I think I've been in line behind you at the dump station. I say your wrong. ;)
BTW, the guys that dump and only use water stink the whole line up. Why is their water not working?
I've tried water only. I'm not going to be "that guy" at the CG again.

My friends all make fun of me for putting computer fans in weird spots.

I'm gonna mount one on top my black tank vent!! At some point I meant to get a reversible fan for the bathroom roof vent. Same idea of keeping odors from rising out the toilet.

I never add chemical. Winter time it's no big deal. Summer temps i was having problems with what I think was gray tank smells. You guys told me to check the vent under the sink. I covered it with a plastic bag last year to test.

Will have to see how it goes this summer.

I think my trailer has tank vent caps that use wind to suck odors out the tank. Doesn't seem to work.

There was a time I goofed up and forgot to dump. Had the trailer on a jobsite. Flushing produced bad smells. Wish I had thought to put a fan on top the black tank vent.

wopachop wrote:
My friends all make fun of me for putting computer fans in weird spots.

I'm gonna mount one on top my black tank vent!! At some point I meant to get a reversible fan for the bathroom roof vent. Same idea of keeping odors from rising out the toilet.

I never add chemical. Winter time it's no big deal. Summer temps i was having problems with what I think was gray tank smells. You guys told me to check the vent under the sink. I covered it with a plastic bag last year to test.

Will have to see how it goes this summer.

I think my trailer has tank vent caps that use wind to suck odors out the tank. Doesn't seem to work.

There was a time I goofed up and forgot to dump. Had the trailer on a jobsite. Flushing produced bad smells. Wish I had thought to put a fan on top the black tank vent.

That would be a sweet mod; Some kind of fan on the vent that automatically kicks in while the toilet flush valve is open. :C