Auto-Flush Toilets


I've been wondering ever since they were installed exactly how the
"auto-flush" toilets are supposed to save water . . . or are they? I've
never seen the advantage in them, but when, recently, and not for the first
time, one flushed three times while I was in the stall, I thought they must
actually be wasting water. I'd like to get an explanation of what their
advantages are and what causes them to get out of adjustment. Does
Maintenance rely on employees to call and report malfunctions, or do they
check the mechanisms routinely? Thank you.

Answered on April 26, 2000


Auto-flush (sensor-operated) valves on toilets and urinals primarily serve
a sanitary function by insuring that waste is not left standing in the
fixtures. When combined with low-flush-rate fixtures, sensor- operated
valves will conserve water. Fixtures in the Mesa Lab operate at between 2
and 3 gallons per flush. Recommended flush rates for water conservation
fixtures are 1.6 gallons for toilets and 1.0 gallons for urinals. The
sensor-operated valves at the Mesa Lab were installed approximately nine
years ago based on recommendations at that time from the Federal Energy
Management Program (FEMP). I have been unable to find a current FEMP
recommendation for sensor-operated valves as a water conservation tool
except for hand washing. A documented account of water conservation
utilizing sensor-operated valves at the Denver Federal Center can be found
on the Web [link no longer available].

I spoke with a customer service engineer at Sloan Valve Company, the
manufacturer of the sensor-operated valves at ML, about your question. The
infrared sensor operating the valve is part of a microprocessor circuit
that is affected by power problems and can cause the sensor to malfunction.
In most cases the problem can be corrected by resetting the microchip. I
have passed this information and the procedure for resetting the units on
to the maintenance people responsible in this area.

Although maintenance personnel do regularly check bathroom facilities for
leaks, there is no routine check of sensor operation. Maintenance does rely
on employees to report malfunctions to the maintenance request line at X1120.

Thank you for you question.

–John Pereira, Director, Physical Plant Services