The answer to 'why is my sump pump rusty water' is that a rusty sump pump is often caused by corrosion or mineral buildup in the pump or its components. This can happen over time as the sump pump is exposed to water, air, and other elements. Symptoms may include discolored, dirty, or smelly water coming from the sump pump.
The most common causes of a rusty sump pump are age, poor maintenance, and mineral-heavy water. As the metal parts of the pump corrode, they can release rust and other sediment into the water. This can clog the pump and lead to decreased performance or even failure.