of a storage and heating tank 16 the water inlet 12 is adapted to be coupled to a source of water to be preheated such as from a cold water supply main via inlet pipe 18 inlet pipe 18 may include a shut off valve 20 according to the usual practice the water outlet 14 is adapted to be coupled via connecting pipe 22 to the water inlet 24 of a conventional hot water heater 26 connecting pipe 22 may include a shut off valve 28 according to the usual practice the hot water heater 26 has the usual water outlet 30 for delivering hot water via pipe 32 to the user upon demand heat energy for preheating the water contained within tank 16 is derived from the exhaust heat of a conventional laundry dryer 34 the laundry dryer exhaust is expelled from the dryer 39 s exhaust vent or port 36 which port is coupled through a section of flexible hose 38 to the air intake port 40 of the invention if desired a lint trap such as a screen 41 may be inserted in the intake port 40 to intercept airborne lint particles after heat energy of the dryer exhaust is transmitted to the water within tank 16 the exhaust is then vented through a flue system to be described more fully below and out through chimney 42 the chimney 42 is adapted to be coupled via a length of flexible hose 44 to a conventional vent or opening to the atmosphere the invention also includes a water outlet hose 46 which is coupled to a condensation draining system to be discussed more fully below the water preheating tank 16 may also include an additional water inlet port 48 and water outlet port.