Nearly all RV’s have holding tanks, the exception, the smaller “Teardrop” and some folding trailers. If your unit has holding tanks, you will, at a minimum have 3 tanks. Fresh Water, Gray Water and Black Water. Sometimes they are referred to as the Fresh Tank, Gray Tank and Black Tank. The color designations have nothing to do with the actual color of the vessel. Gray water is water collected from the shower and sink drains, while black water is strictly from the toilet.
There are a myriad of ways of providing care to the tanks. It seems like everyone and their brother has a “hack” that works for them, but for our discussion, let’s just keep it simple and follow standard industry procedures.
First, glove up! Be sure that you have your drain hose connected to the bayonet connector, (the black 3” fitting on the driver’s side of the rig), and the other end connected to the dump opening using the proper sized adaptor. I always recommend the use of a clear fitting somewhere in the system to see what is coming down the pipe, so to speak! It especially helps me when I am flushing my black tank. I know for certain, when most of the solids have been removed from the tank.
Once connected and verified, pull the valve handle for your black tank-keep the gray closed. Allow all the black water to drain from the tank. This can take several minutes depending on the size of your tank. This is where a clear fitting comes in handy. Yes, it is not pleasant to look at, but trust me, you will appreciate it in the end.
Once, all the black tank contents have been drained out, close the black tank valve and open the gray tank valve. We do this so the not so nasty water can help clean out our corrugated drain hose. Once empty, close the valve.
Many RV’s have a Sani-Flush system that will allow you to add fresh water directly to the holding tanks. Some are strictly for the black tanks, but I have seen a system to flush the gray as well. Use this system to clean that tank out thoroughly-especially when putting the RV into storage. NEVER connect your fresh water hose to a Sani-Flush system. There is potential for backflow to contaminate your hose, which in turn, contaminates the fresh water systems in your rig. I use a cheap green garden hose, reserved for this purpose.
The Sanitary flush system instructions clearly state, to “keep the waste valve open when using”. The reason for this is to prevent an over pressurization of the tank, which can cause it to burst. A bad deal! If you want to completely fill your black tank, run a hose inside and stick it in the toilet bowl. Otherwise, pull the black valve open, turn on the water and flush away. Keep it going until you are satisfied.
Turn off the water, wait for complete drainage and close the valve. Disconnect the hose, disconnect the drain hose from the RV side and Raise the drain hose higher than the dump connection. Let all the residual water drain out. Grab your green hose, place the end in your drain hose and turn on the water, to really flush that hose out.
Drain valves, knife valve or blade valves are all names for the type of valve used on all RV’s. Whether they are electrically, cable or rod operated, they all are basically the same construction. A flat plastic “blade” sandwiched between 2 flanges that have rubber seals on them. There are seal conditioners on the market to help keep them slick. Most valve failures are related to seal failure or seal damage. Either can cause a leak or a valve to not operate properly.
Tank sensors. Those dreaded little electrical connectors in your tanks help with estimating how much waste you have, but they are notoriously inaccurate. They work by electrical conductivity, so anything that touches them, potentially closes the electrical circuit and giving an inaccurate display. In the black tank, paper and human waste solids can adhere to the sensor, and dry. In the gray tank, food particles can do the same. What do you do to clean them?
There are companies that specialize in tank cleaning, a good option if your maintenance does not work. If you have notoriously inaccurate readings, here is what you can do.
Fill the tank up and add a good tank chemical. I highly recommend Tank Techs RX. This stuff breaks down everything. Follow the instructions and you should be good to go. You can also use one of the wand sprayers found at all RV supply stores. If you know where your sensors are, shoot water at them to get the debris off. Wear gloves and eye protection.
A good practice to keep in your routine is to always add a digestive product to your tanks. Keep some water in them especially when travelling. The sloshing of the water will help clean the sensors. And never dump your tanks unless they are at least ¾ full. The water volume will propel the solids down and out.