Black and Gray Water Holding Tank Maintenance

Everyone who owns an RV should be concerned with maintaining its wastewater tanks. Problems with wastewater tanks that can be avoided should be avoided. Wastewater tank repair is expensive. Due to health concerns, many service facilities will not work on wastewater tanks and lines until the tanks have been completely emptied and sanitized. This may be quite difficult when the tank(s) is in need of repair. So, common sense dictates that the tanks should be kept relatively clean at all times. Additionally, improper use of the wastewater tanks can lead to a build up of solid wastes, which in itself may cause the system to fail.

I’ve discovered very simple, effective, and inexpensive methods of maintaining my wastewater tanks in a relatively clean condition at all times. I developed these methods myself through my understanding of chemistry, physics, and biology with a smidgen of common sense thrown in for good measure. I also read my RV owner’s manual. Although we are not full time RVers we use our fifth wheel camper at least one weekend a month. We never use public bathing and toilet facilities. In other words, our wastewater tanks are fairly heavily used. Since I’ve met a number of RVers who don’t seem to know how to maintain their wastewater tanks I thought many RVers would find my tips useful. If you have not been maintaining your tanks I believe you will be pleasantly surprised the first time you employ these tips. I do these things and they work.

1. DUMP A FULL TANK
When you are camping and your RV is connected to a sewer/septic intake, leave the drain valves closed until the tank is full and ready to dump. Dumping a full tank provides a sufficient quantity of water to flush solids from the tank. Leaving the drain valves open allows the water to drain off without flushing out solid waste. That solid waste will collect in the tank(s) and cause problems over time.

2. DUMP TANKS IN ORDER FROM DIRTIEST TO CLEANEST
In other words, dump the black (commode) water tank first, then dump the galley tank, then dump the shower and bathroom sink tank. This way you will be flushing out the dirtiest water with progressively cleaner water.

3. USE WATER SOFTENER
This stuff is amazing and it works. Buy a couple of boxes of powdered water softener at the grocery store. You’ll find it located with or near the laundry detergent products. I prefer Calgon Water Softener because it dissolves quickly in water. Cheaper water softeners work just as well but dissolve more slowly. Dissolve two (2) cups of the water softener in a gallon of hot water. Then, pour the solution down the drain into the empty tank. Use two cups of softener for each wastewater tank in your RV. The tank’s drain valve should be closed otherwise the softened water will just drain out. Then use the tank(s) normally until it is full and drain it normally. Add a cup of laundry detergent to the black (commode) water tank at the same time. This will help clean the tank.The gray water tanks should already contain soap through normal use.

The water softener makes the solid waste let go from the sides of the tanks. If you’ve ever taken a shower in softened water you know that after rinsing the soap from your body your skin will feel slick. That’s because all the soap rinses away with soft water. Softened water also prevents soap scum from sticking in the tub. Get the connection? With softened water gunk washes away instead of sticking. The same thing applies to your RV’s wastewater tanks.

I use one of those clear plastic elbow connectors to attach my sewer drain line to the wastewater outlet on my RV. It allows me to see how well things are progressing during a wastewater dump. Before I began using water softener regularly the black water tank’s water was brown, the galley tank’s water was brownish, and the bathroom tank’s water was white. The first time I added water softener to the tanks the water coming from the black water tank was actually black (not brown) and the kitchen tank’s water was also black (not brownish). The bathroom tank’s water remained white. That told me that the water softener had actually done what I had intended for it to do and made solid waste, which had been stuck to the interior of the tanks, let go and drain away. I added water softener to all the wastewater tanks for the next few dumps to be certain all the solid waste possible had been cleaned away. The wastewater only appeared black on the initial treatment. I now add water softener to each tank once after every few dumps to maintain the system.

Occasionally, I pour a gallon of liquid bleach into each tank to sanitize and disinfect them. I no longer use the blue toilet chemical because it isn’t necessary. I have no odors coming from my black water tank. Generic brand liquid bleach is cheap and very effective.

4. USE A WATER FILTER ON YOUR FRESH WATER INTAKE LINE

Most fresh water contains sediment. Sediment will accumulate in your wastewater tanks and your fresh water lines. It also tends to discolor your sinks, tub/shower, and commode. I use the disposable type and have found that they eventually fill up and begin restricting the fresh water flow resulting in low pressure. That’s how I know it’s time to get a new filter. It works, it’s cheap, it avoids problems, do it.

SOME OTHER THOUGHTS
• I believe occasionally traveling with partially filled wastewater tanks that contain softened water promotes cleaning by agitating the water. The same goes for chlorine bleach.
• I believe this process works faster and more efficiently during warm weather. However, I know it works well even during cool/cold weather.
• I believe the process works best the longer the water softener remains in the tanks. So, I don’t add water softener during periods of heavy wastewater generation. I wait until I know we won’t be generating wastewater quickly so that the softened water remains in the tanks for several days before dumping.
• I add a small amount of chlorine bleach to the fresh water tank twice a year to disinfect and sanitize the fresh water tank and fresh water lines. A weak chlorine bleach solution will not hurt you. However, it certainly makes the water taste bad. When we have chlorine in the fresh water system we use bottled water for drinking and cooking until the chlorine is gone.
• My tanks are plastic and my pipes are PVC.
• Don’t be afraid to use your tanks. Just use common sense about their care and maintenance.
• These tips are inexpensive to do. Some of them don’t cost anything. You have nothing to lose in trying them and I encourage you to do so. I actually feel a certain amount of pride in the condition and cleanliness of both my waste and fresh water systems. Naturally, these tips make dumping a much more pleasant and sanitary procedure.
• If you have odors in any of your water systems these procedures should eliminate them. Odors indicate a sanitary problem and degrade the enjoyment you derive from your RV.
• When my RV is parked and not in use I place stoppers in my sink and tub drains. This allows the wastewater tanks to vent through the vent pipes to the outside instead of through the drains into the RV.