There’s nothing more frustrating than a shower that dribbles or a faucet that barely sputters. Consistently low water pressure is a common complaint in San Francisco, and it’s usually a symptom of a specific, fixable problem. Let’s walk through the most likely causes, from the simple DIY fixes to the issues where you’ll need to call a pro.

Always start with the easiest check first. Unscrew the aerator (the little screen) on the end of your faucet. You’ll likely find it clogged with white mineral deposits or sediment—common in our water. Soak it in vinegar, scrub it clean, and screw it back on. This alone often solves the problem at a single faucet. For showerheads, soak the head in a plastic bag filled with vinegar to dissolve buildup.

If the low pressure is at every fixture in your house, the issue is bigger. First, check with your neighbors. If they’re experiencing the same thing, it could be a temporary issue with the city’s main supply. If it’s just you, the culprit could be your pressure-reducing valve (PRV). This is a bell-shaped device usually located near your main shut-off valve. It can fail or get clogged over time, requiring adjustment or replacement by a plumber.

For older homes, the most common serious cause is galvanized steel piping. These pipes, installed decades ago, corrode and rust on the inside. Over time, the opening inside the pipe shrinks to a pinhole, severely restricting water flow. If cleaning aerators doesn’t help and your home has original plumbing, this is a likely suspect. The only permanent solution is to repipe the affected sections with modern copper or PEX piping.

At Starboy Plumbing, we diagnose low pressure systematically. We’ll check your aerators, test the pressure at your main line, and inspect your PRV. If we suspect corroded pipes, we can often use a camera to see inside. We’ll give you a straight answer on whether it’s a simple fix or a larger project, so you can get back to a strong, satisfying water flow in your home.