Installing Drain Master Electric RV Waste Tank Valves

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Ever since I installed the Waste Master sewer system, I’ve had it in the back of my mind to also upgrade to electric dump valves. Quality electric valves are not cheap but as full-time RVers evacuating the tanks is an ongoing chore, and I feel worth devoting a bit of cash.

Besides making the RV sewer dump task a little easier, installation of electric valves will free up extra storage space in my basement compartment. Best of all maintaining and dealing with sticking manual push/pull rod valves will be a thing of the past.

The electric valves I decided on are manufactured by a company called Drain Master located in Hollister, California. They design and build a top tier product that is made in the USA. I went with their state of the art Pro-Series Drain Master Valve Kit 5886.  Included in the kit are 2  Pro-Series electric valves plus control switches, cabling, and installation hardware. Total cost $448.20 + tax.


(Fair Disclosure: Doug Swarts the owner of Drain Master kindly gave me one of the valves as a promotional sample. A $166.45 value. However, I’m not an affiliate for Drain Master, and I received no monetary compensation for this post. – Ray)

Installing My New Electric Waste Tank Valves

Getting Access to Waste Tank Plumbing

Fortunately for me, this was not my first rodeo when it came to working on my Keystone Cougar fifth wheels enclosed sewer system. Besides installing my Waste Master storage solution a few years back, I’ve also had the extreme pleasure of swapping out a damaged black tank waste valve.

In fact, I’ve done so much work in the belly of the beast that I have a large square of the Coroplast plastic underbelly cut out for easy access to the sewer plumbing. When finished with a job I reinstall the Coroplast access panel with Tek screws into the trailer frame and use 2.88″ Gorilla Tape on the seams. The Gorilla tape sticks well to clean Coroplast and is easy to remove next time I require access.

Coroplast underbelly cutout

Underbelly exposed

Prepping the Tanks and Removing the Old Valves

Before I removed the old valves, I felt it would pay to make sure the tanks were thoroughly cleaned. ESPECIALLY THE BLACK! The cleaner they were the better for me working under the rig with open pipes. For weeks leading up to the job I doubled up on my waste treatments and threw in a few extra black tank flushings. Then, the day before, I gave the black tank an extended flushing with not only the built-in flush system but also with a manual flushing wand.

Black Tank Flushing Wand in Toilet

Removing the valves is usually straightforward, undo four bolts holding it in place and slide it out. I emphasized “usually” because as I learned during a previous repair my rigs plumbing is a little different than most. The black and grey tank output piping is installed opposing each other and then flows into a downward facing Y connector.

Black and gray tank plumbing

Because of this, the valve clearance is so tight it makes removing and installing them almost impossible. My solution was to cut out a small section of the grey pipe and use a rubber boot when re-installing the valves. (Important tip: I installed the rubber sleeve on the grey shower tank side versus the black in case it ever leaked)

Rubber Pipe Coupler Installed

Installing a Pro-Series Drain Master Electric Valve

One thing I love about Drain Master products is the attention to detail in the documentation. I found excellent online documentation on every aspect of the valves and associated hardware. Complete with photos and diagrams. Also, they are one of those companies that you can actually call up and talk with.

The first task was to prepare the mating surfaces. I thoroughly cleaned and carefully inspected the flanges of the trailers sewer piping making sure there were no cracks or chips. Then I added the supplied gaskets to them. NOTE – It was emphasized in the manual to attach the gaskets to the flange and not to the electric valve during assembly.

Gaskets on pipe flanges

Next, I applied the supplied 111 Compound to both sides of the valve blade surfaces. I imagine the Dow Corning Molycote 111 compound acts as a lubricant. I slid the valve between the flanges and slowly worked the pieces together with a slight twisting motion seating the gaskets. Finally, I added the four included nuts and bolts and tightened them up in a cross pattern. The manual states recommended torque of 20 inch/lbs. Basically finger tight plus one turn or so. Over tightening can crack the plastic.

Electric Valve install

The Drain Master electric valves need to be installed with the motor facing up above a level plane. They noted that the optimal position is straight up and down or within a 10 and 2 o’clock range, however, above 3 and 9 is acceptable. Because of the OEM design of my sewer plumbing I had to be satisfied with just a few degrees into the acceptable range. I may change things in the future however it will require some reworking of the plumbing that I wasn’t into tackling now.

valve mounting diagram

Drain Master Electric Valves Installed

Wiring in the New Electric Waste Tank Valves

Once I had the valves physically mounted and confirmed nothing was leaking it was time to move onto connecting up the electronic control switches and wiring the 12-volt DC power source. I decided to install my switches inside the RVs water closet. It would be a convenient place for them located right near the sewer output.

Switches Installed

I cut out a square hole with my Milwaukee Multitool and installed the switch plate with the four supplied screws. I opted to install a master on/off switch for the system. Drain Master has an optional one available, but I went with a different type due to my unique mounting requirements. I found a suitable one from SeaSense at a local marine parts store. I mounted it right next to the Drain Master tank switches.

Next, I ran the data cables from each electric valve to the electronic switches. Black tank valve to the switch labeled Black and Gray to Gray. The data cables easily plug in at both ends with no tools required. There is a second plug on each valve for folks that desire a second set of switches inside the rig.

Data Cables

For the 12 volt power, I decided to run a cable from my battery compartment about 5 feet away versus from the main power distribution panel located 15 feet away in the rigs kitchen. The manual states to use a 5 amp fuse for each valve or if running a pair sharing the same power wire use a 10 amp fuse. For cabling, I had a spare length of 10 gauge wire I had left over from my solar system installation. It would give more than enough current carrying capacity for the job. If you are wondering about wiring sizing Blue Sea has a handy online calculator –

I tapped into a 12-volt line used to power the front landing jacks, awning and slide motors. This circuit has plenty of current capacity to handle the electric waste valves. I attached my ten amp fuse using a standard crimp-on ring connector and ran the 10 GA cable into the underbelly along the same path used by the OEM wiring. Then, up behind the water closest and soldered it onto my system master switch.

Power source with 10 amp fuse

Master On Off Switch Soldered

I then ran a second cable from the switch back underneath and attached it to the two electric valves +12 volt wires. I connected them up using solder and a wire nut. For the -12 volt wires I decided to use the RV frame as my return conductor to the negative side of the battery. I drilled and tapped a hole and sanded off the paint. I used a crimp ring connector, a couple of washers and a Tek screw. For corrosion resistance and better conductively I added some Oxgard anti-oxide paste to the mating surfaces.

Electric valve power hookup

Once everything was connected up, I flicked on the master switch, and both valve switches lit up green indicating closed. Pushing a switch opened the valve and lit up red indicating open. To complete the installation I filled both waste tanks and tested the system. Success! Everything worked perfectly.

I’m pleased with how the install turned out.  I’m looking forward to using them going forward and will come back in around six months time with a full review on how they have performed.

Video Detailing Electric Waste Valve Installation

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