Pressure and flow are related but different
Pressure describes force; flow describes delivered volume over time. A system can show pressure when nothing is running and still provide poor flow through a restriction. The pattern during simultaneous fixture use helps define the next measurement.
Locate the scope
One affected fixture raises different questions from the entire property. Recent cartridge changes, utility work, a partly closed valve, a leak or a well-system fault can matter. Use your utility’s current notices as context, not a substitute for examining the property.
Record rather than adjust
Note when the change occurs and which fixtures are involved. Do not increase a pressure switch or regulator setting to compensate for an unexplained restriction. Have a professional measure at appropriate locations and compare against equipment and plumbing limits.
Request a documented explanation
A useful finding identifies the supply, measurement location, static and flowing conditions, and any pressure loss through equipment. For wells, controls, tank condition and pump performance may be relevant. The proposed correction should follow those findings.
Sources & further reading
Primary references for this guide. Confirm current requirements and notices with the responsible authority.
General information helps you prepare. Actual conditions, equipment instructions and the responsible authority determine the work at your property.