Things You'll Need
Water pumps can be used for many things in the house or work site. Once a water pump starts leaking it's basically worthless. When air enters the water pump via a leak, the pump will begin to suck in the air, causing it to barely pump water, if at all. Luckily the majority of pumps tend to leak in the same exact location, and you can fix them with a few tools in a couple of minutes.
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Locate the leak and turn off the water pump. Look for the area where the water is leaking from--it will usually be from the delivery port. The delivery port is the location where you screw on the pipe that redirects the pumped water.
Remove the pipe from the delivery port with the wrench.
Clean the threads from the delivery port and the pipe with a dry rag. Remove any debris and any remains of teflon tape or pipe thread compound previously used.
Apply a thin bead of pipe-thread compound on the thread of the delivery port.
Connect the pipe back into the delivery port. Tighten the pipe with your hands, then tighten it two turns past hand-tight with your wrench. Do not over-tighten the pipe so that you don't damage the threading of the delivery port.
Turn on the water pump and inspect for leaks. If it continues leaking, tighten it more with your wrench until the leaking stops.
If the water pump is leaking from the body of the water pump, you must return the pump to the vendor for servicing. There is no safe way of fixing a leaking water pump body.