ECO-FLO Products EFCWJ10 Deep Water Well Jet Pump, 1 HP, 20 GPMFrom the ManufacturerECO-FLO Products exceed the competition in flow and head performance. Test laboratory and ISO 9000 facility account for quality built pumps that are all CSA approved. The ECO-FLO committment is to produce pumps for the long term at the best value. Maximum Working Temperature (F)- 77, Minimum working temperature (F)- 35.