What is a water pump?
    The water pump pushes coolant from the radiator through the coolant system, into the engine and back around to the radiator. The heat that the coolant picked up from the engine is transferred to the air at the radiator. Without the water pump, the coolant just sits in the system.

1.1 How to detect engine cooling failure?

   A water pump impeller that falls apart is an all-too-common problem. When the impeller stops performing its function of cooling the engine, there's a risk of breakdown. If precautions aren't taken in time, the risk of breakdown can be irreparable. The engine must be stopped immediately, to avoid further damage, if the engine cooling alarm sounds, if the temperature sensor shows an abnormally high temperature, or if no water is coming out of the exhaust. If it's never used and no longer works, there's no point in forcing the handle. It could make the situation worse. This is where pinoches come in handy. One should be quickly inserted into the suction pipe of the raw water pump to stop the water ingress.The pump cover can then be removed.

What is water pressure pump?
  Everything You Need To Know About Pressure Pumps, Agrinet .Water pressure pumps or booster pumps as they are also known are designed to help increase volume and pressure of water flow from various water sources, to a water outlet.