The water pressure switch is typically located near the well tank. Before removing the switch, make sure the power is off, then take off its cover and disconnect the wiring. Remember how the wiring attaches so you can properly connect it to the new switch.

Then use your wrench to remove the pressure switch (you may need a pipe wrench). Rewrap the pipe threads with Teflon tape, install the new switch, reconnect the wiring and replace the cover.
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