Product Tested: ShurFlo Deluxe 24 volt DC model 2088-474-144 on-demand diaphragm pump, 3 gallons per minute output, with builtin 45psi pressure demand switch. Suggested retail price: $172.00

Ideally, a water pump for a rainwater cistern will use very little electricity, be durable and rugged, and be as maintenance free as possible. The model being reviewed was in daily use for 8 years in a small straw bale house.  Water from the cistern delivers naturally soft water to the washing machine, the toilet, and a hose bib. A 24 volt model was chosen so that it could run directly off a 24 volt photovoltaic (PV) electrical system for this off-the-grid green home. Although the PV system included a 120 volt AC inverter, it was desired to have the pump run off the DC side as this would  guarantee that the pump would have power even if the inverter was not operational. The DC pump would also be more energy efficient as some efficiency is lost by the inverter. This same pump model is also available in 24 volt and 120 volt configurations.

The advantage of a rubber diaphragm pump is that they are very immune to damage from grit and debris in the water. This is important as water is collected off the roof with only a simple sand filter. (more…)