Tuesday, May 17, 2022


Holding tank chemicals — choose carefully

By Greg Illes

Absolutely nobody can tolerate a stinky holding tank. This newsletter and the forums are full of advice on how to eliminate odors, and it’s all for a good cause. Climbing into a stinky RV can just ruin your day.

But what about the methodology? Is it just a case of getting rid of smells? Well, yes and no. There’s a right way and a wrong way, as with so many things in life.

First off, what causes the smell? It’s not the waste in the tanks, it’s actually the bacteria in the waste. Eewww, that’s disgusting. Let’s kill all those nasty bacteria, right? Where’s my can of bacteria poison? Not so fast, pardner. Those bacteria are a natural ecological part of the waste break-down process. Waste must be liquefied in order to be properly distributed through the leach fields and absorbed into the ecosystems downstream from the leach fields. If the waste is not properly broken down, it just solidifies and clumps up. This can be disastrous not only for RV holding tanks but also for dump systems, septic tanks and leach fields. Some states and parks actually prohibit the use of bacterial toxins (usually formaldehydes or derivatives); they are actually carcinogenic as well.

So what’s to be done? “Can’t live with ’em; can’t live without ’em,” as the saying goes. Fortunately, there is a solution — actually many solutions. Providers have come up with a broad selection of environmentally friendly holding tank treatments. Amazingly, these treatments actually encourage the growth of bacteria rather than simply killing them off.

How does this work? As it turns out, the stink mainly comes from poor conditions for bacterial growth — lack of oxygen, primarily. Probiotic tank treatments change the chemistry to promote healthy bacterial growth, which rapidly and odorlessly liquefies the tank contents. This makes dumping easier, and it sure helps the dump system maintain its essential health and efficiency.

To be sure, the use of formaldehyde-based tank chemicals is very effective against odors — but at too great a cost in terms of downstream adverse effects. Try not to be seduced by the easy solution. If you are using poisonous chemicals now, go through the changeover process and be an eco-friendly RVer. Here’s how to do this.

First, select a chemical that is enzyme or probiotic based. Second, execute a very thorough flushing, perhaps several, on your existing tanks so that any residual poison is flushed out. Even a trace of formaldehyde-based chemical will kill the good bacteria needed for proper eco-friendly operation. (Most people who report poor results with enzyme products have not adequately flushed the old poisons from the system.)

When your tanks are spic-and-span, follow the manufacturer’s recommendations for the new chemical. More is not necessarily better — just use what the instructions say.

We went through this process several years ago and our results are spectacular. We used the Bio-Pak, but there are many products to choose from. We never have an odor problem, even in high temperatures and long intervals between dumps (10 days or more sometimes). And we have the satisfaction of knowing that we are doing no harm, perhaps even some good, to the dump stations and eco-systems along our travels.

Editor’s note:  Learn more or order Bio-Pak here or similar products here.

photo: Greg Illes

Greg Illes is a retired systems engineer who loves thinking up RV upgrades and modifications. When he’s not working on his motorhome, he’s traveling in it. You can follow his blog at www.divver-city.com/blog.


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