Why Water Pressure Drops in Fall (And How to Prevent It)

We see an uptick in low water pressure calls every fall in the Upstate. It’s not a coincidence — several seasonal factors converge to affect your plumbing.

Falling Leaves and Outdoor Plumbing

Leaves, debris, and organic matter can accumulate around your outdoor water meter and main supply line entry point. While this rarely causes a direct blockage, debris around the meter box can complicate access during a supply issue, and heavy leaf cover near the foundation can trap moisture against exterior pipe penetrations.

More importantly, fall is when tree roots are most actively seeking water sources as surface moisture decreases. If your main sewer line has any crack or joint gap, fall is when root intrusion accelerates. While this primarily affects drainage rather than supply pressure, a severely root-compromised sewer line can create backpressure that affects the whole system.

Municipal Water System Fluctuations

Many Upstate SC water utilities perform system flushing and hydrant testing in the fall. This can temporarily reduce pressure in your area. If your low pressure coincides with your neighbors experiencing the same thing, contact your water utility before calling a plumber.

Temperature-Related Pipe Contraction

As temperatures drop, metal pipes contract slightly. In homes with older galvanized pipes that are already partially restricted by internal corrosion, this contraction can reduce the effective diameter enough to noticeably decrease flow.

This is another reason galvanized pipes should be on your replacement radar. If water pressure drops seasonally and your home has original galvanized supply lines, repiping will solve the problem permanently.

Pressure Reducing Valve (PRV) Sensitivity

PRVs can become more sensitive to temperature changes as they age. A PRV that maintains 55 psi in summer might drop to 40 psi in cooler weather if the internal spring and diaphragm are worn. PRVs typically last 7-12 years and should be tested during any pressure-related service call.

Fall Plumbing Checklist

Before cold weather settles in:

1. Disconnect garden hoses from outdoor faucets 2. Insulate exposed pipes in crawlspaces, garages, and exterior walls 3. Check your PRV — if you know where it is, verify the pressure with a hose bib gauge ($10 at any hardware store). You should see 50-70 psi. 4. Locate your main shut-off — make sure you know where it is and that it turns freely. In an emergency, seconds matter. 5. Clean aerators on faucets that have reduced flow 6. Schedule a plumbing inspection if your home is over 20 years old and you haven’t had one recently

When to Call

If your water pressure drops suddenly (not gradually), call a plumber. Sudden pressure loss can indicate a burst pipe, a failed PRV, or a main supply issue that needs immediate attention.

YOUTUBE EMBED: One Drain – Waldrop Plumbing Air Electric TV Commercial — @YallCallWally

Call Waldrop Plumbing Air Electric at (864) 536-0887 for a pressure evaluation.

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