by Donna B. Yeaw

Wondering what the difference is between grey water and black water? Want to know when to empty your holding tanks? Or even how to? Don't despair. In this article I will try to address these topics and others. But remember your best resource of information is your dealer. He is the expert on your motorhome and my instructions and advice will be generic.

The two main holding tanks for waste are the grey water holding tank and the black water holding tank. The grey water tank collects water from the sinks, shower and other water-using appliances like a dishwasher (yes, some RVs actually have these) or a washing machine. The black water collects the sewage from your toilet.

The grey water tank typically causes fewer problems and the problems tend to be less severe. Obviously, the potential severity of a black water holding tank problem staggers the mind (and the nose). Before we jump into that topic, let's talk about the dumping of the holding tanks.

There are some basic rules that all RVers should follow when it comes to dumping their holding tanks.

Never use a fresh water hose to dump your tanks. This includes the public hose that is used to provide fresh water for cleanup.

Always use a sewer hose to dump your black water tank.

Empty your black water tank when it's at least half full, preferably three-quarters. The extra liquid helps to breakup and flush out the solids.

Be sure to clean up after you dump. Don't leave a mess for the next person. Do not leave either the grey or black water valves open while parked long term. You risk accumulating a solid waste sludge along with its accompanying odor.

It's always a good idea to carry a spare sewer hose - it's something you don't want to be without!

NEVER, NEVER, NEVER dump your black water tank directly onto the ground. In some areas it is permissible to dump your grey water this way, but never the black water.

The recommended procedure for dumping is as follows. Dump the black water tank first, watching carefully for leaks or spills. Then close the valve and open the grey> water valve. Let a little of the grey water run through the sewer hose to rinse it. Then lift the hose above the holding tank level so that it will fill with grey water. (Oh, some folks carry rubber gloves to wear while performing this "delightful" task. That is entirely up to you!)

Once the hose is full, lift it high in to the air to backflush the water in the hose into the black water tank. Now put the hose back into the sewer drain and finish draining both tanks. When completely dumped, disconnect the sewer hose from the RV, lifting it high in the air again. This will drain any remainders into the dump.

Good job! Now put the hose away, stowing it securely and rinse down any spills that might have occurred. At this point, it is recommended to flush the toilet several times to add some water to the black water tank. This will aid in the breakup of solids later on. This is typically the time you will put in some additives to help control odor and aid in the disintegration of solid waste.

Okay, so you've followed all the rules but you still have a problem. It will usually be one of two things - odor or blockage. Let's attack the odor problem first.

Both tanks can have odor problems. Odors from the black water are somewhat expected but most folks don't think about the grey water tank. Here there may be bacterial growth from a buildup of food particles and grease, particularly after storing the RV for an extended period. There are many products on the market that can help with this problem and, once again, your local dealer can head you in the right direction.

The black water tank is another story. Odors here can be noxious as well as obnoxious. The best bet, besides following the procedures outlined above, is to use additives to fight odor in the tank. Once again, there are many products on the market. This is where you need to talk to not only to your local dealer, but other Rvers as well to see what they recommend. Many RVers are adamant about avoiding products that contain formaldehyde.

You do need to remember that your RV toilet is more sensitive than land-based ones! One RVer put it this way: "Never put anything into the toilet that you haven't eaten first." Although you can purchase toilet paper made specifically for RV toilets, there are alternatives. The inexpensive paper at most discount stores is usually fine for use in a RV. (The first thing we look for is a notice that the TP is safe for septic tanks.) If, after you wet it, you can immediately poke your finger through it, then it's okay to use. Biodegradable is the keyword here!

The other problem that typically occurs with black water tanks is blockage. What do you do if you think your black water tank is stopped up? First, try adding both chemical additives and more water. Then take a drive down the bumpiest road you can find, or least put up with! The sloshing of the water and chemicals may be enough to dislodge the buildup. If it is really bad, it may take multiple treatments to break up the entire blockage. If you can't clear the blockage yourself, then be prepared for a visit to your mechanic.

Remember - prevention is the best cure in this case! So far we have not had a build-up problem but have had to deal with odor s after forgetting to empty our tanks prior to flying out of town for three days! A word to the wise, if you have to leave the RV for more than a day, plan to dump your tanks before you go.

I hope I have answered your basic questions. If not, feel free to e-mail me and I will do my best to get an answer for you. Until next time, keep on rolling !