When building a new sprinkler system or maintaining an existing system, an inexpensive water pressure gauge can be used to check each faucet. Choose irrigation heads that will operate with the pressure you have; irrigation heads are labeled with the optimum pressure range. If the pressure is too low, reduce the number of heads on each valve (you may need to break up the system and add more valves) and run the zones one at a time. Low pressure causes uneven coverage and dry spots. If the pressure is too high to operate the system correctly, a pressure regulator is required. Excessive pressure damages irrigation equipment and wastes water by misting and uneven coverage. Drip irrigation systems always need pressure regulation to operate correctly.