The short answer
What causes low water pressure in a Poway home?
Most low water pressure comes from one of five things: a failing pressure reducing valve, a hidden leak, mineral-clogged fixtures or pipes, aging galvanized plumbing, or a home sitting high above its water supply.
If every fixture dropped at once, look at the valve or a leak first. If it's one tap or one shower, the problem is almost always local to that fixture. Where the weakness shows up is the fastest clue to the cause.
Poway's geography makes pressure problems more common than in flatter towns. The City of Poway treats its water at the Lester J. Berglund Water Treatment Plant and sends it through reservoirs, pipelines and pumping stations to homes at very different elevations. A house near the top of a hill can struggle for pressure, while one lower down may receive so much that a regulator is needed to tame it. Add the region's hard, mineral-heavy imported water and scale becomes a steady factor too.
The good news is that nearly every cause can be found with a gauge and a methodical check, and most of the fixes are routine for an experienced plumber.