Quick Answer:
Cold or stormy weather can coincide with pressure changes because supply systems and local equipment respond to temperature and demand. Start by measuring pressure at an outside hose bib, isolate major components (service entry, regulator, and house valves), and flush lines to rule out local blockage before replacing anything.
Why This Happens
Two common causes link weather to pressure changes:
- Supply-side variation: Municipal systems and private wells can change output during storms or cold snaps. Heavy demand or frozen pipes elsewhere in the system can lower available pressure to your home.
- Equipment sensitivity: Pressure regulators, backflow preventers, or partially blocked service lines react to temperature and sudden flow changes. If a regulator is marginal, cold or surge conditions can make it act up—if you recently changed a regulator, see Pressure low after installing pressure regulator for more on that scenario.
Step-by-Step What to Do
1. Measure pressure at a hose bib
- Buy or borrow a simple pressure gauge that screws onto a hose bib. Attach it to an outdoor spigot on the main supply side (not after a pressure regulator or hose splitter).
- Record static pressure (faucets off). Typical municipal pressures are 40–80 psi; wells can be similar but may cycle.
- Measure during calm weather and again during the storm or cold period to compare. Note both pressure and whether it fluctuates rapidly.
2. Isolate main components
- Locate the main shutoff valve and the regulator (if present). Close and open valves to isolate sections: for example, shut off the house main to see if the service line pressure (if you can measure it) is different from inside the house.
- Check hot and cold separately at fixtures. If only hot pressure drops, the water heater or its valves may be the issue. If both drop, the problem is upstream.
- If pressure behavior looks like the entire town or neighborhood is affected, it’s likely a supply-side issue—if the pressure changes without an obvious local cause, research **Whole house pressure fluctuates randomly** for similar troubleshooting steps.
3. Flush the system appropriately
- Open a full-flow outdoor spigot or the lowest drain in the house and let water run for several minutes to clear sediment. This can help if debris or ice is partially blocking a line.
- For hot water: if the water heater has sediment buildup, draining a few gallons from the drain valve per the manufacturer’s instructions can improve flow and pressure on the hot side.
- Aerators and showerheads can clog with mineral deposits—remove and check them. Replace washers or screens before assuming a larger problem.
What Not to Do
- Do not immediately replace fixtures without verifying service entry issues.
- Don’t open or modify the pressure regulator or service connection if you’re not experienced—incorrect adjustments can cause overpressure and damage.
- Avoid sudden, extensive changes like turning off the main supply without planning; that can cause water heater or appliance issues if done incorrectly.
When to Call a Professional
- Call a licensed plumber if pressure remains low or intermittent after your checks, especially when measurements show low service pressure at the hose bib.
- Contact your water utility or well contractor when multiple homes are affected or if you suspect a main break or supply problem.
- Bring in a pro for regulator replacement, service-line repairs, or when there are signs of leaks, repeated valve failures, or potential frozen/burst pipes.
Safety Notes
- Turn off electrical power to pumps or appliances before working near them. Water and electricity are dangerous together.
- When draining a water heater, follow the manufacturer’s instructions; scald risk is real—allow water to cool or use protective clothing.
- If temperatures are below freezing, take care when opening frozen pipes; do not use open flame. Thaw slowly and safely.
Common Homeowner Questions
- Can weather really change my home’s water pressure? Yes. Supply demand, frozen lines, or equipment sensitivity can cause measurable changes during storms or cold spells.
- Will running faucets during a storm help pressure? Running and flushing lines can clear local clogs, but it won’t fix a supply-side drop from the utility or well system.
- Is adjusting the pressure regulator a DIY job? If you’re comfortable and have the right gauge, minor adjustments are possible; otherwise call a pro to avoid creating overpressure.
For more related articles, see the Whole-House Low Water Pressure hub.