The NAS Defender 110's water pump is a belt driven device which transfers water from the radiator to the engine, hence keeping your engine cool.

Defender 110's water pump is located in the front of the car between the fan/clutch and the engine block, behind the fan belt. It's input attaches to the radiator and output to the engine. should be attached to the engine. These are hollow pipes in reality, where the other arms are simply for All other arms extending from the water pump are added support to keep the water pump in place. As your engine runs, the fan belt turns, turning the axle at the center of the water pump. The pump operates on centrifugal force. In the center hollow part of the pump is the pump's axle, connected to a series of vanes, which turn along with the axle, this turning motion creates suction, pulling water from the radiator. The water reaches the pump and is thrown against the exterior walls of the pump by the power of the vanes which are generating the centrifugal force. As the water circles against the outer wall, it presses down a drain, which sends the water into the engine block. From there it passes into the cylinder heads, and drains back into the radiator for the process to repeat itself.

As the water pump begins to wear, the gasket will erode. As a result coolant will begin to leak through the weep hole (sealed by a gasket) a clear indication that the water pump is no longer able to do its job.

If coolant leak is visible at the water pump and at idle it's best to stop the vehicle, and have it towed to your nearest specialist. If you plan to replace the water pump yourself, return home, and order replacement immediately, otherwise by further driving the vehicle under such condition you risk overheating your engine and doing irreparable damage to it.