The exciting World of Black Holding Tanks! Now, who wouldn’t want to know all they can about this important aspect of their RV? Right? Let’s get right to it, with five important points:
It’s a holding tank, not a septic tank. We run into this ALL THE TIME. Too may RVers treat their holding tanks (both black and gray) as part of a septic system: Waste is deposited into them, chemicals or other additives are added to break down whatever is in them, and, when convenient, they are emptied.
They are not intended to be septic tanks; just holding tanks. They “hold” waste until they are needed to be emptied. Keep this in mind and avoid adding chemicals, enzymes, and a casual “I’ll just pull the handle when I need to” attitude and you’ll be far ahead of the game.
Use enough water. We can’t get this through to RVers often enough. We’re asked why tanks are dirty, why they seem to drain slow, and why they smell so much. It’s because you aren’t using enough water. Strive for at least a 50:50 ratio of solids:water and dump your tanks when they are 90% to 100% full.
Tanks aren’t full but you want to dump? Simple, add water — either through your black tank’s onboard flush system, adding water through the toilet bowl, or simply dumping a large bucket or two down the toilet to get the total volume to as near to 100% as you can.
Prime your black holding tank. When you get to an RV park or site where you can dump the tanks without having to worry about access (i.e. boondocking), add three to five gallons of clean water (depending on the overall capacity of your holding tank) when you get there and after every time you empty them. It’s called “priming” and it gives your holding tank — especially your black one — a fighting chance at keeping clean.
We tend to not use enough water as RVers when we use the toilet so priming the system gives your black tank a little extra water to keep things lubricated and keep the balance of water-to-waste on the high side.
Stop using chemicals and enzymes. Really, your holding tanks only need fresh, clean water to make them work properly. By adding harsh chemicals — and especially enzymes or other additives that break down waste — you are encouraging your tanks to become septic systems where waste breaks down into mushy, sticky, pancake-like batter that will stick to the walls and other surfaces of your tanks, including those sensors that never seem to work.
Your tanks function better when solids (via your toilet) are suspended in a lot of liquid (like water) and are drained frequently when the tanks are 100% full (or filled to that capacity). Broken down, sludge-like waste will only create more problems in the end.
Backflushing and onboard flush systems. These are great ideas and should be used as often as you can. Your onboard black tank flush system is designed to spray and rinse your black holding tank. It’s a good practice to have this running whenever you empty your black tank to increase the volume of water and encourage more fluid movement in the tank when emptying.
Something like the Valterra Flush King is a great way to add another flushing and rinsing element to your black tank (and, especially, your gray tank since it lacks any onboard flushing system). We highly recommend this product and process for ALL RVs.
We hope you learned a thing or two about black tank care and maintenance. If you’re attending one of the rallies we are at this spring, summer, or fall, be sure to attend our seminar on waste tank maintenance. We go over these points as well as others to help you keep your holding tanks clean, carefree, and working properly.