According to RV maintenance experts, here's how to safely and completely evacuate RV holding tanks:
1. Always wear disposable protective gloves when
handling any waste system component and be sure to wash your hands thoroughly
afterwards.
2. Connect the sewer hose. Begin by inserting
the nozzle end of the hose into the campground sewer inlet or dump site, and
open the valve on the nozzle. Walk back towards the termination assembly on the
coach extending the hose only the distance required. Always avoid snaking a
full-length hose back and forth on the ground. If more hose is needed to reach
the coach, simply attach an extension hose when necessary. All quality hose
makers will have extension hoses and connectors. To complete the connection,
remove the protective cap or plug on the RV end and attach it to the
termination outlet. Be sure to maintain the proper slope of the drain hose from
the termination outlet to the sewer inlet.
Known as the “first in - last out” rule,
inserting the sewer end first and removing it last will guarantee no release of
waste water and avoid further contamination on the ground. Note: this is only
applicable if the hose has a positive shut-off valve on the sewer end and a cap
or plug on the coach end.
3. Only evacuate a holding tank (black or gray)
when it is over 3/4 full. Yes, contrary to what some veteran RVers may tell
you, this means leaving the gray valve fully closed while in the campground.
Filling each tank to a level above the 3/4 mark before evacuating will ensure
you’ll have enough volume (and velocity), to thoroughly drain the tank and
flush the hose.
Here’s another reason for keeping the gray
holding tank valve completely closed except during evacuation. Ever walk
through a beautiful, scenic campground and catch a whiff of sewer odor wafting
through the park? Kinda ruins the moment, right? All coaches with the gray tank
valve in the open position (sewer hoses obviously connected), are simply acting
as a direct conduit to the park’s sewer system. Each coach becomes a mini-vent
of sorts, in parallel with the septic system of that campground. No wonder
sewer odors still abound in the nicest of destination sites.
Follow the logic; a large septic system in a
campground will have fundamental venting designed into it, but with numerous RVs
connected to that system with their gray tank valves open, odors can rise up
through the park’s septic system, through the sewer hoses of those coaches,
through their empty gray holding tanks and up the vents of those holding tanks.
Remember, it may be your gray tank, but it’s the campground’s black and gray
odors coming up and through it. The only problem with this scenario is that the
gray tank vents on the RVs are a lot closer to the ground and more prominently
located than the park sewer stack so odors are more noticeable. By keeping the
gray tank valve closed until the tank is almost full, you will eliminate the
localized venting of the campground sewer gasses at your particular site. The
more RVers who follow this precept, the less likely we’ll have to endure septic
odors in and around the campsite.
4. Evacuate the black tank first. This is pretty
much standard procedure and something most all coach owners are aware of, but
it’s worthy to mention it again.
After the black tank empties flush it out with a
large amount of fresh water when connected to city water. Simply keep flushing
the toilet while the termination valve remains open. If you opt for the
Polychute or Drainmaster hose, monitor the cleanliness of the water through the
integral Clear-Vu fitting as it drains. There are other clear fittings
available for the bayonet-type hose adapters as well. When the draining water
is relatively clear, stop flushing, close the gate valve and cover the bottom
of the black tank completely with fresh water.
Permanently installed holding tank spray kits
are available in the aftermarket that attach to each holding tank thereby allowing
fresh water to be directly induced into the tank after dumping, but I’m
hesitant to drill mounting holes into holding tanks. Plus I like to flush all
components of the waste system including the toilet, sink drains, etc., so I
prefer to simply flush the toilet and run water through the sinks.
5. Evacuate the gray tank last. After the black
tank has completely emptied and its termination valve properly closed, open the
gray tank valve and empty that holding tank. Be sure to rinse this tank as well.
Dumping the gray tank last utilizes its liquid contents, as well as the fresh
water induced after dumping, to help wash away any solid waste that may remain
in the sewer hose.
6. Drain the sewer hose. After both tanks have
been emptied for the last time at that location, take the time to thoroughly
rinse the sewer hose with fresh water until clear water is viewed through the
Clear-Vu fitting on the sewer hose. After closing the gray termination valve, remove
the sewer hose from the termination outlet on the coach and, if so equipped,
secure the plug to the hose and the termination outlet. Then begin “milking the
hose.” In other words, raise the hose at the coach end and walk it towards the
sewer inlet. Keep raising the hose as you walk, thereby “milking” the hose and
emptying it completely of water. Even a properly sloped flexible sewer hose may
have residual water and waste particles left inside. These particles will
become an odor generator over time, so it is imperative to completely remove as
much moisture as possible.
7. After milking the hose and as you reach the
campground sewer inlet connection, close the positive shut-off valve on the
sewer nozzle and disconnect it from the campground sewer inlet. Remember the
“first in - last out” rule! With the cap on the coach end and the nozzle valve
turned off on the sewer end, all remaining odors stay inside the hose. Cap the
sewer inlet and then stow the hose and add an enzyme-based additive to all
holding tanks.
8. Check the P-traps. Unless you upgrade to
HepvO waterless sanitary valves, every month or so, look down each sink drain
and the tub/shower drain to ensure the water seal is still there. In some waste
system configurations, a quickly draining tank can actually cause the water
lock to be siphoned out of the trap. You’ll probably have to use a flashlight,
but it is essential that a water lock remain at all times. Remember, this is
the primary method of preventing gray holding tank odors from entering the
interior of the coach. Bottom line; a dry P-trap is nothing more than a
shortcut for odors to gain entry into the RV.
Following these correct and complete evacuation procedures will be appreciated by everyone!
