Quick Answer:
If your water pressure improves when it rains, the most likely cause is a short-term change in the municipal system — lower overall demand or higher supply during storm events. Before making any in-home changes, track pressure readings over time and compare them to city demand patterns to confirm the timing and cause.
Why This Happens
Municipal water systems change pressure based on supply, demand and reservoir levels. Rain can reduce overall neighborhood demand (people use less outdoor water) and refill supply sources, so pressure in the mains can rise briefly. Soil saturation and reduced pump cycling can also change distribution pressures.
Other common reasons you might see pressure shift with weather include aging mains that respond to transient changes, pressure-reducing valves adjusting to different flow, and neighborhood water use patterns. If you’ve noticed similar timing issues at other times, see pages like Pressure weak during heat waves and Pressure fine midday but poor at night for related patterns to compare.
Step-by-Step What to Do
1. Gather a simple gauge and pick a log format
- Buy a basic faucet pressure gauge (screws onto an outdoor hose bib) or borrow one from a hardware store.
- Set up a simple log sheet or spreadsheet to record date, time, weather (raining/not raining), and gauge reading (PSI).
2. Log pressure at several consistent times
- Take readings before, during and after a rain event when possible.
- Also log at representative times on dry days: early morning, midday, evening and late night. Aim for at least two weeks of data to see patterns.
3. Correlate readings with city demand patterns
- Contact your water utility to ask about typical peak usage hours, scheduled pumping, or known pressure zones in your area.
- Compare your log to the utility’s information. Note whether higher pressure aligns with lower city demand or reservoir refilling during storms.
4. Check simple in-home items
- Confirm the main shutoff valve is fully open and that no single fixture is consuming large flow when you test.
- Look at the visible pressure regulator (if you have one) for obvious leaks or damage. Don’t disassemble it unless you’re comfortable and trained.
5. Interpret the results and plan next steps
- If pressure consistently improves only during rain and matches utility patterns, the issue is likely at the municipal level or related to overall neighborhood demand.
- If pressure is low independent of rain or your readings show irregular drops, collect more data and consider a professional inspection.
What Not to Do
- Do not replace in-home plumbing before confirming municipal timing patterns. Replacing pipes or fixtures without evidence wastes money and may not fix the problem.
- Do not rely on a single reading — avoid making decisions from one test during unusual conditions.
- Do not attempt major work on the main supply or public-side equipment; contact your utility for anything beyond your property boundary.
When to Call a Professional
- Call a licensed plumber if low pressure persists regardless of rain, or if you find signs of leaks, rust, or failing pressure-regulating equipment.
- Contact your water utility if your readings show neighborhood-wide pressure swings, or if a technician’s input is needed to interpret system-level data.
- Bring a log of your pressure readings and the times you took them — that information speeds diagnosis and avoids unnecessary work.
Safety Notes
- Turn off the main shutoff before doing any repairs inside; if you’re unsure where it is, locate it before an emergency.
- Do not work on equipment attached to the public water main. If you suspect the issue is on the utility side, call the water department.
- If you notice a large leak or a burst pipe, evacuate the area of flooding, shut off water, and call a plumber immediately. Electrical hazards around water need professional handling.
Common Homeowner Questions
Why does my pressure get better only when it rains?
Short answer: Rain often lowers neighborhood demand and raises supply levels temporarily, which can increase pressure in the mains.
Will a booster pump solve the problem?
Short answer: Not necessarily. A booster helps in-home pressure but won’t address municipal supply or timing issues; confirm the cause first.
How long should I log pressure before acting?
Short answer: Aim for two weeks of readings at different times and weather conditions; more data gives a clearer picture before you spend money.
Related Articles
If you’re troubleshooting a similar symptom, these guides may help:
For the full directory, see Water Pressure Changes by Time of Day.