Avoid Waste Tank Headaches

While not the most enjoyable of tasks, frequently dumping at appropriate times will prevent unnecessary problems during your RV trip.

We like to think that RV ownership consists of 85 percent enjoyment and 15 percent maintenance for any particular motorhome or trailer. However, it’s when you ignore the 15 percent that the headaches set in, and it’s usually when you least expect it.

Whether you buy new or used, you’re a newbie or seasoned RVer, or you just escape for a few weeks during the season, having a strict ethic of RV maintenance and care is essential to avoid potential headaches on the road.

There are a number of systems of any given model that always need some TLC. Some are seen every time you use your RV - such as the interior fans or slides -  others like your black and grey tanks are not, since they are concealed somewhere within the depths of your unit. Even though they are out of sight, they should never be out of mind. In other words - make a note to self and routinely empty them.

Dumping waste tanks is not the most glorious part of RVing and this task definitely falls into our 15 percent category. We like to compare it to the never-ending task of taking out the garbage at home, but this waste is an entirely different anomaly.  You need to know when to empty them, how often to empty them, why it’s so important to empty them and the consequences if you don’t. After all, you don’t want to be ‘that guy’ who delays the lineup at the RV park’s dump station.

When to Empty Your Waste Tanks

Grey and black tanks vary in capacity, depending on the size of an RV. Typically, they range from 20 L (5 gal) in compact trailers to 550 L (145 gal) in larger coaches or fifth wheels.

While it’s a given that smaller tanks will need to be emptied much more frequently, it’s important to know when - or the frequency  - to dump them.  Of course, it depends on your use. A good rule of thumb is they should be emptied when they are about 75 percent full. Take our word for it, don’t wait for the tanks to reach capacity as they may overflow. This is when the headaches begin.

While most tanks have a gauge to indicate the current capacity of waste or greywater, dumping your tanks every three to five days after routine use is good practice, depending on the size of the tanks, the number of people in your family, etc. If you lose track of time on the road and you see a dump station at a campground or in a park, simply estimate their fullness and perhaps empty them for good measure.

Managing Odours, Clogs and Other Problems

Whether you’re a full-timer on hookups or a transient RVer, ensure that the blackwater valve is always closed as this invites an early opportunity for odours and even clogs to form - but they can also start when the valve is closed just due to the nature of the waste.

We believe in waste tank treatment solutions and after some trial and error, we found one we liked for the black water tank in our Montana High Country 305RL. So far, it has been very effective (see Full-Time Highs and Lows; Snowbirds and RV Travelers Volume 19 number 1).

While it’s designed to prevent clogs and odours by liquifying the black water, waste residue can still potentially accumulate over time, especially if the waste stagnates in the tanks for several days or you don’t dump as frequently as you should. The consequences are ugly waste residue that can sometimes build up on the sides and bottom of the tank.

This accumulation - or the grime from dishwater, grease, and oils - in the gray tank - can accumulate and cause the sensor probes to stop functioning properly, hence the importance of clearing the tanks at appropriate times.   

The Importance of Using Water

There’s a common misconception that if you don’t run a lot of water or accumulate that much waste, dumping is not required. Rather than learning the falsehood of this the hard way, remember the less water you use, the greater the chance of clogging and odours (and other headaches). So, be sure to use plenty of H20 when flushing and other tasks.

Additionally, when boondocking, there’s a tendency to conserve water by using less when you flush and stretching out the time between dumping. This strategy will also ultimately result in a clogged blackwater tank.

Water maintains the efficiency of bacteria that develop in the tanks and can essentially manage the odour. Although a smell may occur despite the water level at any given time, we once again stress the importance of dumping the waste tanks every three to five days or when your tanks are about 75 percent full.

Dumping waste tanks at any time during a trip is not the most enjoyable task. What is even less enjoyable, however, is dealing with the consequences of not dumping enough, which results in the lines clogging, failed sensors, odours, and a variety of other headaches. So, it’s always best to follow these best practices to ensure smooth travels during your next RV trip.

Aftermarket Solutions: Store Your Waste

If you like to escape off the grid for a few days, you have a few options when dumping stations are not available, including aftermarket portable waste tanks. Easy to use with tight sealing qualities and offered in a variety of sizes, they simply hook up to your unit’s sewer connection and you dump the gray or black water as you normally would from your RV’s system. We like the Camco Rhino (about $300 CA from Amazon).

These will not only provide extra capacity but prevent your RV’s tanks from reaching their limit and eliminate the worry (or consequences) of not dumping your tanks when required.

Two Great Ways to Clear a Blackwater Tank

At some point, virtually every RVer ends up with a clogged blackwater tank, which can result from not using specific RV toilet paper that’s designed to easily break down in the tank as residential paper doesn’t do this quickly enough. But most clogs are the result of not flushing with enough water.

There are two strategies we’ve found that work to clear clogs. The first is for those worst-case scenarios. For instance, you finally get your turn at the dump station with a long line behind you, a full blackwater tank, and a long drive home ahead.

As soon as you realize the black tank isn’t flowing, stop and don’t panic and follow these procedures:

  • Close the blackwater tank valve (BTV) and open the valve on the greywater tank.
  • When you see greywater flowing into the dump station, immediately lift the hose above the level of your grey tank. With the hose lifted, it will fill with greywater.
  • Close the greywater valve and with the blackwater valve open, lift the hose a little higher and ‘walk’ the hose about 1 m (about 3 ft) toward the RV.
  • Quickly lower and raise the hose a few times.
  • After a few times working the hose up and down, drop it quickly to the ground and you should hear the blackwater tank draining. Happy day.

This may sound like the instructions to an awkward line dance but what’s really happening is you are backflushing the greywater against the clog in your blackwater tank.

Our Ultimate ‘Always Works, Solution

This procedure requires some advanced planning.

  • Take a trip to the hardware store and purchase 1.5 - 2 m (5-6 ft) of ½” PEX (cross-linked polyethylene), which is a flexible plastic pipe. The pipe alone could be enough to solve your problem if you fill the black tank with water, but we like to attach a hose using either a 3 cm (.5 in) garden hose fitting (to connect to a garden hose) or better still, a 3 cm (.5 in) PEX to a 3 cm (.5 in) shower hose fitting.
  • Crimp, clamp or sharkbite the fitting to your PEX so it doesn’t fly off. Make sure your BTV is closed.
  • Remove the showerhead and connect the shower hose to the fitting.
  • Push the PEX down the toilet, turn on your hot water and start working the PEX up and down everywhere it can reach in your blackwater tank.

This method worked for us within a few minutes when every other gadget we tried failed - and there are plenty out there. This solution is cheap and when you’re done, you can throw it away as the PEX and fitting are less than $5.