There are many RV black tank clean-out options available. Some work better than others and their effectiveness is largely dependent on the RV plumbing configuration.
This week I am reviewing the "Dual Flush" clean-out solution. This item is available in the RV section of your local WalMart.Cleaning your black tank thoroughly is VERY important! I learned this lesson the hard way when I first began RVing. I didn't wash the black tank out thoroughly and toilet paper remaining in the sewer pipes dried forming a hard plug. The next time I pulled the "T" handle, nothing came out. I had to snake it out enduring an avalanche of brown and I NEVER want to repeat that experience again!
The old school way to clean out the black water tank is to use a wand connected to a hose inserted into the toilet. This is a very effective way to clean out your tank, but you have to contend with dragging a hose into your RV. Another method is to install a spray clean-out that has an outside connection for the hose and sprays directly into your black tank. There are several variations on this method and here is a link to a previous story: The Tornado
The simplicity of the Dual Flush device is it's strong point. There is no need to drill holes in your holding tank, you just attach it to the existing clean-out and hook-up a water hose. It has a valve that allows you to squirt water up into the plumbing or down into the sewer line.The problem with this device is that it will not work efficiently with all plumbing configurations. It works on my RV because the black tank empties directly down into the clean-out pipe. On my previous 5th wheels, it would not have worked because the clean-out pipes were too long and contorted to allow the Dual Flush spray to effectively wash away the sludge. It's still not as effective as the old school wand because it does not completely spray all the surfaces of the tank interior. I like the see-through design because you know when the water is running clear.
The down spray is an effective way to wash down your flexible sewer hose. I like this feature because it allows you to wash the hose without disconnecting. You won't spill a drop on the ground or yourself with this feature.As with all see-through sewer connections, they don't last. My experience for the life expectancy for these connections is anywhere from six months to a year before they break or become opaque.
Jim Twamley - Professor of RVing