A grey water heat recovery apparatus has first and second passes arranged in counter-flow orientation. The heat recovery apparatus is made from commonly available materials. It has a hot side for grey water, and a cold side for fresh water under pressure. The heat recovery apparatus extracts heat from grey water to pre-heat water for a water heater. The fresh water is carried in passes in series, each pass being immersed in a grey water sump in a plastic pipe. The water level in the sump is high enough to immerse the dominant portion of the fresh water pass in grey water. Both ends of the fresh water coil are carried out through the same upper end pipe closure, without a penetration in the pipe wall. The entire assembly may be enclosed in a unitary external housing with easily accessible connection fittings.