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Using Your RV : Tips & tricks

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How to Dump Your RV's Tanks
Russ and Tiņa DeMaris

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It's one of those deep mysteries to many new RVers. Even though it's not right that it should be a deep mystery, should you improperly dump your tanks, you'll find out how quickly you can get into it pretty deep! Actually, dumping RV tanks is easy, once you have the basics down.

It's important to know you should wait to dump your black water tank until it is at least two-thirds full. Why? Because if you dump your black water with less than that amount, the solids may not get flushed out of the tank. Over time those solids can build up in the bottom of the tank, forming a hard, blocking mass that can prevent you from dumping the tank at all.

And please, dump your tanks ONLY at an appropriate facility. Not only is it illegal (and costly in you're caught) to dump them elsewhere, it gives all RVers a nasty black eye when the media rolls out a story about some yo-yo who dumped his tanks down a storm sewer or worse. We'll go into finding dump stations in a later story.

Roll your rig up so that your dump port connection is close to the dump station apron--that way, if you spill anything (it happens!), you can easily wash the mess down the drain. It may be helpful to have a "spotter" until you can gauge this by looking in your mirror.

Next, we like to check to make sure the rinse hose at the station works--there's nothing worse than finding out after you've dumped that there's no water to rinse the hose out.

Now, PUT ON GLOVES. We keep a pair of PVC coated industrial gloves in an outside compartment for this purpose. Some use toss-away latex gloves and replace them every dump.

Fresh water valve open. R&T DeMaris photo.
On most rigs you'll have a single connection point on your rig to dump both the black and gray water. And in case you're not up your nomenclature--black water is that nasty stuff that emanates from your toilet, and gray water from the shower and sinks. Your RV's dump fitting will likely by a "bayonet" style fitting, Slide the hose fitting onto the RV fitting and give it a clockwise twist until it's tightly locked on. NOW PULL on that fitting to ensure that it's really locked in place. The "macho" side of our RV team once failed to check for that locking on a truck camper fitting. When it came loose, in the middle of dumping black water, Mr. Macho was UNDER the camper and took a thorough shower of yuck--NOT a pretty sight, but one that caused the "fairer sex" part of the team to run away far enough to laugh without repercussions.

Next, place the free end of the dump hose firmly into the dump station receptacle. In most cases you'll find you don't need a fitting on the "transmitting" end of the hose. You'll often find previous RVers have left a big rock at the station to lay on the hose to make sure it doesn't pop out of the receptacle--saving untold frustration and embarrassment.

With the hose in place, coupling on RV checked, pull the lever that dumps the BLACK water first. Not sure which is which? Check your rig's owner manual. A giveaway on many rigs is that the black water tank feeds to the dump port through a large (typically 3 or 4 inch) pipe, while the gray water feeds through a much smaller pipe. Dumping the black water first then leaves you a tank full of gray water to wash down any nastiness left in your hose from the black water session.

When your black water is empty, close the black water valve, then open the gray water valve. Some cagey RVers, particularly "boondockers" who may have spent considerable time parked in one place (and hence, not "stirring" the contents of their black tank by vehicle motion) alter this procedure. After the black water tank is empty, they leave the black tank valve open, yank open the gray water valve for a few seconds, allowing gray water to rush up into the black water tank, and do a little extra tank rinsing. They then slam the gray water valve shut, allow the black water tank to re-empty, then close the black valve and complete their dumping by reopening the gray valve and completely emptying out the gray tank.

Once you've got both tanks emptied, make sure the valves on both are firmly closed. Now "milk" the dump hose out, by carefully picking it up, starting at the RV end, and working the remainder of the fluids in the hose out to the dump station end of the hose. This is particularly important where there's a curb between your rig and the dump station--we've found many Flying J truck stops with this ill-design.

Once the hose is emptied out, carefully disconnect the hose from your RV, leaving the dump station end in place in the station receptacle. Using the rinse hose, wash out the dump hose, then remove it from the station receptacle. Depending on the layout of the dump station (and the amount of traffic backing up behind you), you may consider using the rinse hose to blast out the RV dump port connector. Be sure to rinse off the pavement at the dump station. Be sure to put the "termination" cap back on your dump port fitting.

And one more thing: For obvious reasons, don't use the dump station rise hose to fill your fresh water tank.

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