Rust in hot water is usually caused by sediment that has built up over time in the water heater. Bits of rust and dirt collect over time from the water supply and can flow into the water as it is pumped through the heater.
Rust is oxide of iron metal. The substances are dissolved in the water are affected rust in hot water. Salts and acidic substances are cause more rust in hot water. In hot water chemical reactions are takes place very fastly.
the rust or scaly substances formed in the water when it is heated is due to the dissociation of certain salt contents in the water. these salts may also be the hardness causing substances.
