Clean Water Pumps will be used wherever the water would be unlikely to contain particles, and they tend to operate to between 5 & 10mm minimum height as opposed to the usual 25 - 50mm of a dirty water pump as they don’t need to allow for particles passing through the pump.
(Examples of jobs suitable for Clean Water Pumps include: emptying water tanks, rainwater butts, swimming pools.)
A Clean Water Pump
Dirty Water Pumps are used for clearing out water that is likely to contain solid particles, so water that is muddy for example. They tend to work to operate to a minimum water height of 25 - 50mm so that they allow the particles to pass through the pump and avoid blockages. Particle size allowable through a pump can vary greatly; some will even let small stones through.
A Dirty Water Pump
(Examples of jobs Suitable for Dirty Water Pumps - clearing floodwater, emptying a cellar, emptying ponds, ditches and dykes.)