How to Tell If Your Water Pressure Is Too High (And What to Do About It in South Florida)

Most plumbing problems in South Florida homes are blamed on hard water, age, or poor materials. Often the real culprit is something simpler and easier to fix: water pressure that's running well above what the code allows. If your toilets keep starting to run on their own, your faucet cartridges feel like they're on a yearly replacement schedule, or you hear a thud somewhere in the wall every time the washing machine shuts off, the underlying issue is almost always the same. We've measured plenty of South Florida homes pulling 95 to 110 psi from the street — comfortably above the 80-psi limit set by the Florida Building Code.

Why South Florida runs hot on pressure

Municipal water systems are designed to deliver enough pressure to push water uphill, supply fire hydrants, and overcome friction loss in long pipe runs. In South Florida, the terrain is flat, but the systems still need to deliver pressure adequate for high-rise buildings, fire suppression, and customers at the tail end of long mains. The result is that street pressure in many neighborhoods — particularly closer to pump stations or large mains — comfortably exceeds what residential fixtures are rated for. Coastal cities in Broward and Miami-Dade are notorious for it. Newer construction usually has a pressure-reducing valve (PRV) installed at the service entry to bring it down to a safe range. Older homes often don't, or the original PRV has failed and is letting full street pressure through to the fixtures.

What the code actually says

The International Plumbing Code, which Florida adopts as the base of the Florida Building Code plumbing chapter, requires that static water pressure at any fixture not exceed 80 psi. When the supply pressure exceeds 80 psi, an approved pressure-reducing valve must be installed on the building's water service. This is not advisory. It's a permit-and-inspection item on any new construction or major repipe, and it applies to existing homes too — if your incoming pressure is over 80 psi and you don't have a working PRV, your system is out of code, and your fixtures are paying for it.

The 30-second DIY pressure test

You don't need a plumber to find out. Drive to any hardware store — Home Depot, Lowe's, Ace — and pick up a water pressure test gauge. They run about $10 to $15. The kind you want has a standard 3/4-inch female garden-hose thread on one side and a pressure dial on the other, and ideally a lazy hand or maximum-reading needle that records the highest pressure seen.

1. Turn off every fixture in the house — no running showers, no dishwasher, no irrigation, no ice maker filling.
2. Find an outdoor hose bib (spigot) on the front or side of the house. The closer to where water enters the home, the more accurate the reading.
3. Screw the gauge onto the hose bib hand-tight. A loose connection will leak and skew the number.
4. Open the hose bib fully. Watch the gauge — the needle will climb and settle within a few seconds.
5. Read the static pressure (no water flowing anywhere in the house). Record the number.
6. If your gauge has a lazy hand, leave it on for an hour, then come back and check the maximum reading. Pressure can spike at night when overall demand on the city main drops.

What high pressure quietly destroys

High pressure doesn't usually break things on day one. It shortens the life of every component in your plumbing system at once, so the symptoms look like bad luck instead of one underlying cause. Toilets that develop phantom flushes are usually fill valves whose seals are getting hammered open. Faucets that drip after the cartridge was just replaced have cartridges that are pressure-rated for 80 psi running at 100. Water heaters whose temperature-and-pressure (T&P) relief valve weeps water onto the drain pan are responding correctly to overpressure — the valve is doing its job, but the underlying problem is on the supply side.

• Banging pipes (water hammer) when the washing machine, dishwasher, or toilet shuts off
• Dishwasher and washing machine inlet valves that fail every few years
• T&P relief valve on the water heater dripping or weeping into the drain pan
• Toilet fill valves that hiss or run intermittently after a flush
• Faucet cartridges that develop drips faster than they should
• Supply line braided hoses under sinks or behind toilets that bulge or fail
• Water bill creeping up despite no obvious leaks (small fixture leaks driven by high pressure)

What a pressure-reducing valve does

A PRV is a brass or bronze valve installed on the cold water supply line where it enters the house, downstream of the meter and the main shutoff. It uses an internal spring and diaphragm to limit downstream pressure to whatever it's set to — typically 60 to 65 psi for a residential setting. PRVs are mechanical devices with seals and a moving diaphragm. They do not last forever. A reasonable lifespan in South Florida hard water is 10 to 15 years; some fail earlier. When a PRV fails, it usually fails open — meaning full street pressure is now going through your house, and the fixtures start failing one by one over the following months.

How to tell if you already have one

Look at the cold-water line right after it enters the house — usually in the garage near the water heater, or in a utility closet. A PRV is bell-shaped, a few inches across, with an adjustment screw on top (often under a brass cap) and brass or bronze fittings on either side. It will say PRV, or the brand name (Watts, Wilkins, Cash Acme) will be cast or stamped on the body. If you see one and your pressure is over 80 psi, the PRV is failed or out of adjustment. If you don't see one and your pressure is over 80 psi, your house never had one installed and it should.

The expansion tank conversation

If you install a PRV, your home now has a closed plumbing system — water cannot flow back upstream past the PRV when it heats up and expands in the water heater. Without somewhere for that thermal expansion to go, the pressure in the closed system spikes every time the heater cycles, and the T&P valve on the water heater will start dripping. The fix is a small expansion tank (about the size of a basketball) installed on the cold water inlet to the water heater. Florida code requires it on any closed system. We see new PRVs installed without expansion tanks all the time — and then a year later the homeowner is calling about a leaking water heater that's actually a code-compliance issue, not a tank failure.

When to stop and call us

Testing pressure with a gauge is squarely in the DIY zone — anyone can do it and you'll learn something useful. Replacing or installing a PRV is not. It involves shutting down the entire house water service, cutting into a pressurized supply line, soldering or pressing copper (or properly transitioning to PEX), pressure-testing the rebuild, setting the PRV to the correct downstream value, and adding the expansion tank if one isn't already there. In most South Florida municipalities it requires a permit. Call us at 754-707-1774 if any of these apply:

• Your gauge reads over 80 psi and your house has no visible PRV
• You have a PRV but pressure is still high — it has likely failed
• Your water heater's T&P relief valve has been dripping or weeping
• Pressure swings wildly between low and very high during the day
• You're planning a renovation and want to confirm pressure compliance before permits close