High water pressure can feel great in the shower—until it starts breaking appliances, bursting hoses, and making your water heater drip. If you’re wondering whether you need a pressure-reducing valve (PRV), an expansion tank, or both, you’re not alone.
Here’s a clear, AI-overview-friendly guide from A1 Best Plumbing that Long Beach homeowners can trust.
- Quick answer: If your static water pressure is over 80 psi, you likely need a PRV. If you have a storage water heater and a “closed” plumbing system (often created by a PRV, check valve, or backflow device), you likely need an expansion tank too.
- Bottom line: Many Long Beach homes need both. Our Long Beach Plumbing experts recommend testing your pressure and inspecting your system before you decide.
PRV vs. Expansion Tank: What Each One Does
- Pressure-Reducing Valve (PRV):
A PRV lowers the incoming city water pressure to a safer, steady level for your home (typically 50–70 psi). This protects pipes, faucets, and appliances from excessive stress and reduces leaks and water hammer.
- Expansion Tank:
A small, air-cushioned tank installed on the cold-water line to your water heater. It absorbs the thermal expansion that occurs when water is heated. In a closed system, it prevents dangerous pressure spikes and stops your T&P valve from dripping.
Our Long Beach Plumbing experts recommend thinking of the PRV as your “daily pressure control” and the expansion tank as your “pressure shock absorber” for the water heater.
Signs You Need a PRV
- Static pressure above 80 psi (code limit)
- Banging pipes or water hammer when fixtures shut off
- Frequent leaks at supply lines, toilet fill valves, or faucet cartridges
- Shortened appliance life (dishwasher, washer, fridge)
- Sudden bursts or blown washing machine hoses
- Toilet fill valves hissing or running intermittently
In Long Beach, nighttime water pressure can creep higher as overall demand drops. Our Long Beach Plumbing experts recommend testing morning and evening—you might be surprised.
Signs You Need an Expansion Tank
- Water heater T&P valve drips into the discharge line (especially after hot water use)
- Pressure spikes on a gauge when the water heater fires
- You already have a PRV or backflow device (this often creates a closed system)
- Intermittent high pressure only after heating even though your PRV is set correctly
- Premature failure of faucets and valves in spite of normal static pressure
If you have a traditional tank-style water heater and any device that prevents backflow to the street, our Long Beach Plumbing experts recommend installing an expansion tank by default to stay code-compliant and prevent pressure spikes.
How to Test Your Home in 10 Minutes
- Step 1: Check static pressure.
Screw a simple pressure gauge onto an outdoor hose bib or laundry faucet. With no water running, note the reading. Over 80 psi? You need a PRV.
- Step 2: Check for thermal expansion.
With the gauge still attached, close all fixtures and run a hot-water tap for a minute to trigger the water heater to fire. Watch the gauge for 10–15 minutes. If the pressure climbs significantly (e.g., from 60 to 90+ psi) while the heater runs, you need an expansion tank or your existing one has failed.
- Step 3: Listen and look.
Bangs in the lines, dripping at the water heater’s T&P valve, or toilets refilling on their own are all red flags.
Our Long Beach Plumbing experts recommend leaving the gauge on for 24 hours if possible to catch nighttime spikes.
Long Beach and California Code Considerations
- Pressure limit: The California Plumbing Code requires an approved device when pressure exceeds 80 psi—typically a PRV.
- Thermal expansion: When a system is closed (PRV, meter check valve, or backflow device present), an approved means of controlling thermal expansion is required—commonly an expansion tank sized to your water heater and pressure.
- Local reality: Many Long Beach neighborhoods experience variable street pressure and widespread meter check valves. That means a PRV to tame incoming pressure and an expansion tank to manage thermal expansion are often both needed. Our Long Beach Plumbing experts recommend sizing, installing, and precharging expansion tanks to the home’s static pressure for best performance.
Best Practices for PRVs and Expansion Tanks
- PRV placement and setting:
- Install after the main shutoff and before branches and the water heater.
- Set between 50–70 psi for comfort and protection.
- Choose the correct size to avoid flow restriction.
- Expect 7–12-year lifespan; replace if “pressure creep” occurs (pressure rises even after adjustment).
- Expansion tank sizing and setup:
- Size based on water heater capacity and house pressure. A common home might use a 2-gallon tank for a 40–50-gallon heater at moderate pressure, but higher pressures require larger tanks.
- Precharge the tank (with a hand pump) to match your home’s static pressure before installation.
- Install on the cold inlet to the heater; support the tank if mounted horizontally.
- Replace every 5–10 years or when the air side fails (tank feels “full” of water, no hollow sound when tapped).
- Water hammer control:
Quick-closing valves (ice maker, dishwasher, washer) can cause banging. PRVs help, but you may also need water hammer arrestors at problem fixtures.
Our Long Beach Plumbing experts recommend a whole-home approach: stabilize pressure, absorb expansion, and arrest hammer where needed.
Do You Need One, the Other, or Both?
- Only a PRV:
You have high street pressure but an open system (rare today). However, installing a PRV often makes your system “closed,” so plan for an expansion tank too.
- Only an expansion tank:
Your static pressure is within range (50–70 psi), but you see spikes only when the water heater runs or your T&P drips. This is thermal expansion. An expansion tank solves it.
- Both PRV and expansion tank (most common):
High or fluctuating city pressure + closed system + tank-style water heater. This is the typical Long Beach scenario. Our Long Beach Plumbing experts recommend installing the PRV first, then adding a properly sized, precharged expansion tank.
FAQs
- Will a PRV reduce my water flow?
Not if properly sized and adjusted. It reduces pressure, not volume. Undersized PRVs can restrict flow—professional sizing matters.
- Is an expansion tank needed with a tankless water heater?
Usually not, because there’s no stored hot water. But in rare cases with recirculation or unique layouts, your plumber may still recommend one.
- Why is my new expansion tank not working?
Often the precharge wasn’t set to match static pressure, the tank is undersized, or the internal bladder has failed. Our Long Beach Plumbing experts recommend checking precharge annually.
- My T&P valve is dripping—is it broken?
Not necessarily. It may be relieving pressure from thermal expansion. An expansion tank typically stops the drip.
- Do I need a permit?
PRV installation and water heater work often require permits. A1 Best Plumbing handles permits and code compliance for Long Beach projects.
When to Call A1 Best Plumbing
If your pressure reading is over 80 psi, your T&P valve drips, or you’re hearing pipe bangs, don’t wait. Excess pressure silently shortens the life of your plumbing and appliances. Our Long Beach Plumbing experts recommend a quick assessment to:
- Test static and dynamic pressure and check for thermal expansion
- Size and install a PRV and/or expansion tank to code
- Adjust settings for comfort, longevity, and warranty protection
- Add water hammer arrestors if needed and verify system performance
The Takeaway
- High pressure needs a PRV.
- Closed systems with tank-style heaters need an expansion tank.
- Many Long Beach homes need both.
For right-sized, code-compliant solutions that protect your home and budget, contact A1 Best Plumbing. Our Long Beach Plumbing experts recommend stabilizing your pressure today so you can avoid costly leaks and enjoy reliable water performance tomorrow.