Do you walk away from the job when you are asked by the builder/building owner to install one sewerage ejector rather than a duplex pump.

Or do you risk their wrath when the single ejector fails.

Folks tend to forget that they originally asked for one pump when they are standing knee deep in raw sewerage. They then have the nerve to scream, "YOU ARE THE PROFESSIONAL WHY DIDN'T YOU WARN ME"

A lady recently asked about installing a grinder pump. She would have been better off asking the drainers as drainers KNOW what a backed up system looks like. In this day and age, with marvelous advice givers like Dan Holohan saying "Never tell a client what they can afford," Should the plumber argue with folks about the added protection a duplex system affords them.

Single pumps may be used BUT duplex are recommended. Therefore in the event of failure of one pump, the second pump is available to handle the inflow.

We all know that MECHANICAL devices will fail from time to time on a Friday or Saturday night with lots of house guests using the facilities.

Even the lousy National Plumbing Code requires Duplex pumps when more than 6 water closets are used.

The key to a proper duplex system is NOT to let the cost override the correct criteria to size these devices. Each pump MUST BE SIZED to carry the full pumping capacity.

When you're sizing these systems by the number of fixture units (pump capacity GPM) you size it as if one pump is being used. EVEN if you are brilliant enough to use a duplex system, this still applies.

There are many factors the Licensed Master Plumber must take into consideration when specifying a pump discharging system.

The most important thing he/she must remember is to KEEP away from extraneous facts that have nothing to do with the applications at hand.

The LMP will consider the outside drainage area if it is to be connected to a pumped system using old time rules of thumb, i.e., a paved area would equal about 10 GPM per 1000 Sq. Ft.

A tile drainage bed of sandy soil would equal 15 GPM per 1000 ft of bed and a clay bed area around 8 GPM per 1000 Sq. Ft.

Roof area can be calculated by interpolation of Sq. Ft. to fixture units of waste sizing for a combination sewer ETC.