Our final batch of answers to your RV holding tank and waste handling questions

Today is the third part in our series of questions and answers from this year’s rally seminars. We met hundreds of attendees at the sixteen rallies we did and had some great questions asked. Be sure to check out Part One and Part Two if you missed them. Otherwise, here we go (and there are five bonus questions this time, making ten total!):

Q. Can I use the GEO method of keeping my holding tanks clean?
A. The GEO method is a mid-1970s sort of “home-brew” method of keeping your RV’s waste holding tanks clean. The basic idea was to create a mixture of Borax (a water softener), Calgon (or another detergent), and bleach (along with water, to dilute the mixture). This was used as a tank additive in lieu of enzymes, bacterials, or harsh chemicals, such as formaldehyde.

The basic concept is sound, however, Borax is a very harsh alkaline chemical that can corrode metal parts (such as the sensor nubs in your tanks). Detergent should be avoided in black tanks (it’s hard to not have it in your gray tanks!) as it can reduce the slipperiness of plastic holding tank surfaces over time. Finally, bleach is highly corrosive and will eat away soft rubbers and plastic, such as are found in your tank’s valves and seals.

A better option to Borax is Calgon, which is not nearly as corrosive. Adding Pine-Sol or another pine oil cleaner to the solution is preferred, as it has disinfectant qualities and strong odor-masking properties. For the “recipe” to formulate your own tank additive, please visit this link.

Q. How good of a job does my black tank flush system do?
A. Your RV’s black tank flush system sprays water in a “set” pattern at approximately 100PSI-150PSI (due to the reduction in hose size and spray nozzle opening). While this is better than nothing, it doesn’t have enough force or volume to remove sticky waste on the surfaces of your tank, nor can it adequately remove build-up against the front (downslope) wall of your tank, where waste collects.

That being said, be sure to turn on your black tank’s flush system while emptying the black — the extra turbulence from the flush system will help to move waste out of your black water holding tank.

The only way to get your holding tanks truly “factory clean” is through the process of extremely high (1500PSI) water pressure and the continued use of adequate water usage and a tank solution to keep them that way.

Q. Why do my gray tanks smell worse than my black tank sometimes?
A. For one thing, no current RV manufacturer includes an in-tank rinsing system for their gray tanks like there is in the black tank. This lack of a rinsing process means that waste only leaves the tank when it is emptied. Many RV owners leave gray tank valves open all the time, further promoting the lack of complete tank emptying (waste mounds up or is left behind and begins the process of decomposition).

Additionally, a lot of RV owners do not add any sort of tank additive to their gray tanks, thinking incorrectly that they are only intended for black tanks. Adding to the problem is the likelihood that RV owners are not using enough water in their tanks (either before emptying or a part of a “priming the system” action after they have been emptied and before using them again).

Q. Everyone says that I should empty my black tank before my gray tank. Is this right?
A. Ready for a revelation? No! Do not empty your black tank before your gray one(s). But here’s the catch: Open your gray tank pull just a little bit, allowing some of the (relatively) clean wastewater to coat the sides of the sewer hose first. Then, close the gray tank pull, drain the black tank (turn on your built-in flush system during this process — more turbulence!), close the black tank pull, then drain the remaining gray tank(s).

Why do you open the gray water tank pull first? The relatively clean water in your gray tank “sticks” to the interior surfaces of your dry(ish) sewer hose (the “slinky”), creating a barrier. When the black tank wastewater then travels down the hose, it is likely to travel at a faster speed (there’s already a barrier of “clean” water on the interior of the hose). Following up with the gray tank water will completely clean the inside of the hose.

We know, it sounds weird, but it’s physics!

Q. Should I leave water in my holding tanks when I am not using my RV?
A. If you are leaving or storing your RV for a short period of time (a few days to a couple of weeks), then it is okay to leave water (not waste!) in your holding tanks. In fact, 3-5 gallons will help keep things lubricated and you’ll be ready for traveling to your next destination or continued use of the RV where it is located.

Longer term, no, we do not recommend that you keep water in your tanks, and, certainly not any waste. If you are in an area where temperatures could drop below freezing for any amount of time, you can see the danger of allowing any liquid to freeze and potentially damage waste system components.

Q. Can I use Dawn or another detergent in my holding tanks?
A. Your RV’s holding tanks are basically large, plastic boxes. Detergent, like Dawn, should be avoided in black tanks (it’s hard to not have it in your gray tanks!) as it can reduce the slipperiness of plastic holding tank surfaces over time. As the tank’s surfaces become less slippery, waste will have a tendency to stick to them. This is especially true if you are using an enzyme, biological, or harsh chemical that breaks down waste into a thick, sticky, pancake batter-like mess.

Q. What’s your opinion of macerators in my RV’s sewer handling system?
A. Macerators have pros and cons. One of the cons is that they tend to be complex pieces of machinery that can break (especially the impellers) from time to time. Also, pumping out waste through the small (1″ to 1-1/2″ in diameter) hoses can take longer than through a standard 3″ sewer hose. You also lose the vortex or “tornadic effect” of emptying the tank due to the slowness of the waste leaving vs. through the larger diameter sewer hose. On the pro side, macerators seem more convenient and are certainly a less-messy way to empty your holding tanks.

From our perspective, cleaning holding tanks with a macerator attached or built-in can be difficult (resulting in more time, and thus a higher cost) or, sometimes, impossible.

Q. How often should I empty my holding tanks?
A. Whenever they need to be emptied — or you need empty them (when you’re about to travel, for instance)! The key here is to make sure to empty them when they are 90%-100% full of water. This allows sufficient down-pressure from the full tank of water or liquid to create a vortex or “tornadic effect” in the tank, driving liquid and waste out of the tank (as opposed to a slow seep, leaving solids behind).

Also, remember to “prime the system” by adding 3-5 gallons (depending on the total capacity of your tank) to each holding tank after emptying and prior to using again.

Q. Can you sanitize your holding tanks?
A. Well, there’s no way to — or reason why you would — sanitize your black and gray holding tanks. They are designed to hold human, food, and other waste which is, by definition, not sanitary.

There is a process to sanitize your fresh water holding tank and you should follow it religiously. It involves introducing a mild solution of household bleach into your fresh water holding tank and water plumping system, letting it sit for a period of time to sanitize, quickly getting the bleachy water out of your holding tanks, and rinsing with fresh, clean water (to remove any trace bleach which can affect the taste).

Q. Why do RV sales centers, salespeople, and manufacturers and vendors of enzyme-, biological-, and chemical-based tank solutions say you should use those over your methods and recommendations?
A. It’s a good question, and probably the one we get asked the most. For one thing, there’s an ignorance in the industry: Everyone is frustrated that tank sensors don’t read accurately, but few realize that adding tank additives that break down waste is what is actually creating the problem (the tank’s contents becomes a thick, sticky, pancake batter-like mess).

We’ve cleaned nearly 1,000 holding tanks on hundreds of RVs, from travel trailers to fifth wheels to motor coaches. In every case, we can tell when tank additives are used. What slowly comes out of an “empty” tank is a river of sludgy and smelly mess. Every time. Looking for a better alternative? Try our recommended solution. Click here for the recipe.

Well, that’s it for our three-part series on questions and answers from our 2018 rally seminars. If you have any other questions we didn’t cover here or in Part One or Part Two, please feel free to contact us via email, telephone (815-508-3878), or by using the convenient ask-a-question form below.