The pump has a flow detector built in, which automatically shuts it off once the water stops flowing. Milwaukee stresses in diagrams for this tool that it's only intended to be used with clean water.

The system is activated using a hand-operated pump, which creates pressure in the main unit and forces the ‘dirty’ water ...

An average home has approximately 125 ft of 3/4 inch piping. 125 feet of 3/4" pipe holds 3.14 gallons of water. 10 draws per day wastes over 31 gallons of water waiting for the water to get hot.