Low Water Pressure in Your New Hampshire Home: Causes & Solutions

Low water pressure is one of the most frustrating plumbing problems for New Hampshire homeowners — a weak shower, a slow-filling dishwasher, or a trickle from the garden hose can signal anything from a simple fixture issue to a serious pipe problem. Here are the 8 most common causes of low water pressure in NH homes and what you can do about them.

1. Corroded or Mineral-Clogged Pipes

New Hampshire has notoriously hard water in many regions — particularly in Hillsborough, Rockingham, and Merrimack counties. Over decades, mineral deposits (calcium and magnesium scale) build up inside galvanized steel pipes, gradually restricting flow. In older NH homes — especially those built before 1970 — severely corroded galvanized pipes are the #1 cause of whole-house low water pressure. The solution is full or partial repiping with copper or PEX.

2. Faulty Pressure Regulator

Most NH homes connected to municipal water have a pressure-reducing valve (PRV) near the main water shutoff. This device regulates incoming pressure to a safe level (typically 50–80 PSI). When a PRV fails, it can cause pressure to drop dramatically or fluctuate unpredictably. A PRV replacement by a licensed NH plumber is a relatively simple and affordable fix.

3. Partially Closed Main Water Valve

This sounds simple, but it's surprisingly common — especially after repairs or renovations. Check your main shutoff valve (usually near the water meter or in the basement) and the curb stop valve. If either isn't fully open, restricted flow causes low pressure throughout the house.

4. Leaking Pipes

A hidden pipe leak — inside a wall, under a slab, or underground — diverts water before it reaches your fixtures, causing pressure drops. Watch for unexplained wet spots, mold, high water bills, or the sound of running water when no fixtures are in use. In NH's freeze-thaw climate, pipe leaks from frost damage are particularly common following harsh winters.

5. Municipal Supply Issues

If you're on city water in Manchester, Nashua, Concord, or another NH municipality, occasionally the water supplier may have pressure issues due to main breaks, demand spikes, or system maintenance. Check with your water utility if pressure drops suddenly and affects the whole neighborhood.

6. Clogged Aerators or Showerheads

If only one fixture has low pressure, mineral deposits in the aerator or showerhead are the likely culprit. Unscrew the aerator from the faucet tip or the showerhead from the arm, and soak in white vinegar for a few hours. This simple fix costs nothing. If you're in a hard water area of NH (most of southern NH qualifies), do this annually.

7. Water Demand Conflicts

Large NH households or homes where multiple appliances run simultaneously often experience pressure drops when demand peaks — multiple showers, dishwasher, and laundry at once. This is normal to a degree, but if it's severe, your home's water supply line may be undersized. A licensed plumber can assess whether upgrading from 3/4-inch to 1-inch supply line makes sense for your household.

8. Well Pump Problems

Approximately 45% of New Hampshire residents rely on private wells. If your pressure is dropping, the cause could be a failing well pump, a failing pressure tank, or a dropping water table (especially during dry summers). Annual well pump inspections are recommended — and if your pump is over 10–15 years old and you're experiencing pressure issues, replacement planning is wise.

What To Do Next

Start with the simple checks: aerator cleaning, valve positions, and checking with your water utility if on city water. If those don't solve it, call a licensed NH plumber for a comprehensive pressure diagnosis. We use pressure gauges and diagnostic equipment to pinpoint the exact cause — no guesswork.