This is a subject that seems to baffle a lot of people. There are hundreds of products and methods on the market to help take you money because no one ever taught us how to use the holding tanks in our RVs. So with a little time and effort I hope to shine some light on this problem and the solution.
The tanks in your RV is a holding tank not a septic system. It is a plastic bucket with three holes in it. One to allow stuff into the tank, one for a vent that goes to the roof of the RV and another that leads to a valve for draining. Kind of simple. There are various methods of providing a indication as to the level of fluids in the tank. None of them are very reliable, mainly because we don’t do our part to maintain the cleanliness of the tank.
Operations of the these holding tanks is also pretty simple. You dump stuff into the tanks and when full dump them. Now for the had part. There are methods all over the place and advice that will differ from just about everybody. But the simple truth is these are HOLDING tanks. That mean they are designed to hold the stuff we put in them until dumped. What I mean is KEEP THE VALVES CLOSED! Notice I have not talked about grey or black tanks. This is for a reason. The processes and procedures are the same. Keep the valves closes. You would be surprised at the amount of food, hair, and other stuff that collects in the bottom of the grey holding tank because people think it all flows out the drain. IT DOESN’T, it sits in the tank and collects and over time starts to rot and smell. Since there is no method of flushing it out with a wand for example, it stays there, forever!
When do you flush the tanks? This is an excellent question. The answer is so simple, when they are full. You will quickly learn when the tanks are full. They have a habit of filling up when you take a shower and the water backs up, when you are washing dishes and the shower starts to back up, when you use the toilet and the water burbs at you and the room starts to smell. Then it is time to dump the tanks. But what do you do if at the end of a camping trip your tanks need to be dumped and they are not full? Fill them! Flush water down the toilet until it is full, dump water down the sinks until it is full. Just consider this as one of the tasks of breaking camp.
Before we get into the procedures I want to talk about another tip. Get a clear plastic sewer hose attachment for connecting two hoses together. Place it somewhere in the sewer line that is easy to watch. This way you can see when the tank has emptied completely. It will also aid in letting you know when you rinse the tank if it is clean or not.
Now to dump the tanks. Start with opening the black tank valve first. Let it dump completely. You will see when it is done in the clear section of the sewer hose. If you have a black tank flush system, now is the time to use it. Follow the manufactures recommendations. Most of the ones I have seen say that the tank valve must be open when using. This just prevents Mr Murphy from helping you create a Robin Williams RV moment (If you haven’t watched the movie RV, do so). When the water runs clean, turn off the black tank flush. If you do not have a black tank flush, use your toilet. Fill the bowl and dump it until the water runs clean. This could take a while when you first start as there could be all kinds of crap in the tank that has to be flushed out.
Once you have dumped and cleaned the black holding tank, close the valve and put a few gallons of water into the tank. Fill and flush the toilet about 4 times. This will put enough water in the tank to help keep things from getting hard as the RV sits until the next trip.
Now open the valve(s) to the grey holding tanks. Wait for the tank(s) to drain. Unlike the black tanks there isn’t an easy way to flush the tanks. There are some attachments you can use, that connect to the dump station that allow you to close off the sewer line, connect water hose to the connector and back flush the tanks. I have used one called King Flush that I like, but there are others out there. The point is, you want the water coming out of the tank running clear. Close the valve and again put a couple of gallons of water into the grey tank to keep things from getting hard while it sits.
One more tip, if you are one that wants or has to have the grey tank open when you are camping, make sure you put a dip in the sewer hose. This will act as a p-trap and keep the sewer gases out of your RV.
It works by keeping a little water in the lower part of the hose so gases and bugs can’t come up from the campground sewer system.
Hope you have had a great Memorial Day Weekend. Say a prayer for our fallen Heros.