Abstract: A hot water system comprising a hot water heater and conduit means coupled to feedwater under pressure for conducting water to and from the hot water heater. The system also includes an injector pump and a reverse osmosis module which has an inlet port, a product water port and a brine outlet port. The injector pump has an inlet coupled to the feedwater under pressure, a brine port coupled to the brine outlet port of the reverse osmosis module and a discharge port coupled to the conduit means. The injector pump includes a first valve operated by the injector pump for opening and closing the inlet of the injector pump. A second valve is provided between the reverse osmosis module and the brine port. The injector pump provides water to the inlet port of the reverse osmosis module and increases the pressure of the brine at the discharge port of the injector pump to greater than the pressure of the feedwater so that the brine can be injected into the hot water system.