Flushing brown sludge from a hot water heater
I have a Rheem (Australian) electric hot water heater (160 litres). The hot water is discoloured a browny yellow colour. I believe there may be a brown (iron oxide) sludge in the tank. The heater has 3 connections - the pressure relief outlet, the hot water outlet (at the top) and the cold water inlet (at the bottom). There is no drain plug as far as I can see. How should I go about flushing out this sludge?
Hope you can help and thanks in anticipation
Peter