Suitable for a WH2500 Waterhouse pump It is a plastic and magnetic spare part in a pump. This part is found inside the pump, which is used to drive the water out the pump, and their warranty is limited as they get worn out like a Tyre of a car. Application Impellers are used on specific pumps and models. It is advised that you use the exact size impeller for a specified pump model. Note: impellers need to be cleaned now and then to increase their life span, as they can get worn out and the dirt can cause the pump to get clogged.