RVers sitting for long periods of time in RV resorts, etc. tend to leave the gray water valve open because it is inconvenient to go outside to pull the valve every few days. This
practice leads to future problems with bad odors coming from the tank through the vent pipe. In general, people know enough to not leave the Black valve open for extended periods because the waste will clog the 3" hole and fill the tank! The gray tank will not suffer this major problem,
but will share the odor problem.
Until recently, RV manufacturers had to place the slide valves at the sidewall of the RV for customer access. The small valve on the gray water was just not questioned and became standard over the years.
One of the most common design flaws is the use of gray holding tanks with a smaller than 3" drain opening. By using 3" piping on gray water, the tanks are emptied 2.57 times faster allowing more of the build up and scum to exit the tank. With the use of electric valves manufacturers are able to place the valves at the tank outlets which greatly reduces, if not eliminates blockages.
With the Drain Master Evacuation System, the valves are left closed at all times, except when actually emptying the holding tanks. The Drain Master Evacuation System uses two 3" electric waste valves, one on each tank. The Drain Master system also recommends that the RV manufacturers also include tank sprayers on the gray tanks. The additional use of Sewer Master, the industrial evacuation hose insures total confidence when emptying the holding tanks. A major customer benefit. Many RV manufacturers have recognized the value of changing to the Drain Master Evacuation System.
Drain Master 12VDC electric waste valve provides a positive, more sanitary method of emptying RV holding tanks. Manual, hard to reach, dirty and difficult to operate waste valves are now virtually obsolete. Drain Master requires only the simple flip of a switch to open or close waste valves when emptying the holding tanks. Drain Master is more reliable over time, placing no stress on attached plumbing and uses the same amount of pressure each time it is operated. Compact design allows RV manufacturers significantly more flexibility when designing holding tank location and valve placement. Drain Master incorporates a constant torque clutch preventing the possibility of gear stripping and features double sided manual override should a loss of power occur. Drain Master was designed with reliability as the top priority.