The gauge is easy to use. To measure your static water pressure: turn off all the water in the house and then simply screw the gauge onto a hose bib and turn on the water. The gauge will indicate your pressure in pounds per square inch. For testing dynamic water pressure turn the red needle back to the zero mark and leave the gauge on the hose bib for a day. The gauge features a red needle that will stay put at the highest pressure recorded so no need to check it periodically. Once you know your pressure you can determine whether or not you need a pressure regulator for your drip irrigation.