Intro

On many jobs, the loud bang after a faucet closes drives clients crazy. Here’s the fix that works fast. A very smart plumber shared a trick! Start with pressure, not pipes. Set house pressure to 50–60 psi, then add a hammer arrestor at the noisy fixture. Secure loose lines. Most water hammer stops without opening walls. In this guide, you’ll get simple steps, clear measurements, and the tools you need. Do it in under an hour on most homes. It’s safe, clean, and repeatable. You’ll look like a hero.

Quick Answer

To stop water hammer fast, start by checking pressure and set the PRV to 50–60 psi. Add a water hammer arrestor within 6–12 inches of quick‑closing valves, and secure loose pipes (PEX every 32 inches, copper every 6 feet). This combo fixes most banging in 30–60 minutes.

Table of Contents

• Why "A very smart plumber shared a trick!" Works
• Tools and Prep
• Step-by-Step: The 10-Minute Diagnosis
• Fix It: Pressure, Support, Arrestors
• When to Upgrade or Call It Out
• Estimate and Communicate the Fix

Key Takeaways

• Set house pressure first: 50–60 psi solves many bangs.
• Place arrestors 6–12 inches from quick‑closing valves.
• Support runs: PEX every 32 inches, copper every 6 feet.
• Most fixes take 30–60 minutes with basic tools.
• Document your steps and set client expectations upfront.

Why "A very smart plumber shared a trick!" Works

Water hammer is a pressure spike. It happens when a valve snaps shut fast. Think washer, dishwasher, ice maker, or touch faucets. The plumber’s trick is simple: control the spike at the source and reduce system pressure.

Do three things in order. One, set pressure with the PRV around 55 psi. Two, stop pipe movement with proper supports. Three, add a hammer arrestor near the noisy valve. This order fixes the root cause with minimal parts and time. You avoid tearing drywall unless lines are damaged or inaccessible.

Many contractors find this reduces callbacks. It’s a clean, tested method you can repeat on every service call.

Tools and Prep

Gather what you need before you start. Keep it simple.

• Pressure gauge (hose‑thread type)
• Adjustable wrench and channel locks
• PRV tool/hex key (varies by brand)
• Water hammer arrestors (AA/Mini‑Rester for 3/8" or 1/2" lines)
• Pipe supports: clamps/cushioned hangers
• Tape measure and marker
• Teflon tape or thread sealant
• Flashlight and towels

Safety first. Shut water if you’re cutting lines. Wear eye protection. Always check for electrical near dishwashers and laundry.

Step-by-Step: The 10-Minute Diagnosis

Use this quick field test on every call. It’s the heart of “A very smart plumber shared a trick!”

1. Attach the Gauge

   • Screw the pressure gauge to an outside hose bib or the laundry spigot.
   • Static pressure over 80 psi is a red flag. Aim for 50–60 psi.

2. Run the Culprit Fixture

   • Start the washer fill or snap a fast‑close faucet shut.
   • Watch the needle. A big jump means hammer.

3. Listen and Map the Bang

   • Note where it’s loudest. Wall behind the washer? Under sink?
   • Check for loose straps or pipes knocking studs.

4. Check Supports and Lengths

   • PEX should be supported every 32 inches (horizontal) and roughly every 4 feet vertical.
   • Copper can go up to 6 feet between supports (1/2"–3/4").

5. Inspect Valves and Hoses

   • Old angle stops or washing machine hoses can slam shut.
   • If valves stick, plan to replace.

This diagnosis takes 10–15 minutes. It tells you if pressure, supports, or arrestors will do the job—or all three.

Fix It: Pressure, Support, Arrestors

Here’s the field‑proven order that saves time.

1. Set the PRV (15–30 minutes)

   • Locate the Pressure Reducing Valve near the main.
   • Turn the screw/bolt to adjust. Clockwise raises, counterclockwise lowers (check your model).
   • Target 55 psi. Under code, keep it below 80 psi.
   • Re‑test with the gauge as you cycle a quick‑close valve.

2. Secure the Lines (10–20 minutes)

   • Add cushioned clamps where you hear movement.
   • Support PEX every 32 inches horizontally; copper every 6 feet.
   • Keep 1/4"–1/2" clearance off sharp edges. Avoid tight 90s that rub studs.

3. Install Hammer Arrestors (20–30 minutes)

   • Use mini‑resters at the appliance or fixture.
   • Place within 6–12 inches of the fast‑closing valve for best results.
   • Common spots: washing machine box (1/2"), dishwasher line (3/8"), ice maker (1/4" adapter as needed).
   • Use Teflon tape on threaded connections. Don’t overtighten.

4. Final Test (5 minutes)

   • Run the culprit fixture again. Listen.
   • Watch the gauge. You want smooth drop and no spike.

Tip: Old “air chambers” (stubbed tees) waterlog and stop working. Use PDI‑rated arrestors instead. They last longer and stay effective.

When to Upgrade or Call It Out

Sometimes the quick fix isn’t enough. Note these cases in your estimate.

• No PRV Installed

  • If city pressure sits at 80–120 psi, install a PRV. Plan 45–90 minutes depending on access.

• Long Fast‑Close Banks

  • Multiple solenoid valves (big ice maker, espresso machine lines) may need two arrestors.

• Old Angle Stops and Hoses

  • Sticky stops slam. Replace them. Stainless washer hoses are safer than rubber.

• Copper With Loose Holes

  • If copper rattles in studs, you might need plastic isolators or to open a small section of wall.

• PRV Won’t Hold

  • If pressure creeps back up after you set it, the PRV may be failing. Replace it.

Document these findings. Clients appreciate clear reasons and options.

Estimate and Communicate the Fix

A clear explanation avoids haggling and callbacks.

• Use Simple Language

  • “Your water pressure is high at 85 psi. We’ll set it to 55 psi. We’ll add arrestors within 6 inches of the washer valves and secure loose PEX every 32 inches.”

• Give a Straightforward Timeline

  • Diagnosis: 10–15 minutes
  • PRV set/replace: 15–90 minutes (access dependent)
  • Arrestors and supports: 20–45 minutes

• Line Items Clients Understand

  • Pressure check and PRV adjust
  • Mini‑resters (2) at washer box
  • New angle stops (as needed)
  • Pipe supports and noise isolation

If you’re also working on paperwork skills, this pairs well with understanding professional proposals, clear project timelines, and invoice templates that save time. Good communication closes small jobs fast and builds trust for bigger work.

How to Use "A very smart plumber shared a trick!" On Site

Make the phrase your checklist. Say it out loud if you like.

1. Pressure first: set 50–60 psi.
2. Support second: clamp to stop movement.
3. Arrestors third: install within 6–12 inches of the valve.
4. Test and document: note readings and results.

Repeat this order on every noisy line. It’s quick, clean, and works in most homes.

FAQ

What causes water hammer in a house?

A fast‑closing valve stops water suddenly. The moving water has nowhere to go, so pressure spikes and the pipe bangs the framing. High pressure and loose supports make it worse.

Will a water hammer arrestor fix every case?

Not always. It fixes many. You also need proper house pressure (50–60 psi) and solid supports. If the PRV has failed or pipes rub studs, address those too.

Where should I install the arrestor?

As close as you can to the quick‑closing valve, typically within 6–12 inches. For washers, use mini‑resters at the washer box. For dishwashers, add one on the 3/8" supply line.

Is adjusting the PRV safe to do?

Yes, if you know the valve and have a gauge. Turn small increments and re‑test. Keep it below 80 psi. If the PRV drifts or sticks, replace it.

How long does a typical fix take?

Most homes take 30–60 minutes: 10–15 for diagnosis, 15–30 to set pressure and secure lines, and 20–30 to add arrestors. Hard access or replacements add time.

Conclusion

Here’s the bottom line: start with pressure, then support, then arrestors. That’s why “A very smart plumber shared a trick!” sticks—it’s a fast order that solves the real cause. Next steps: 1) carry a hose‑thread gauge, 2) set PRV to ~55 psi, 3) stock mini‑resters and cushioned clamps. For clean paperwork and quick approvals on small fixes, tools like Donizo help you turn notes into a branded proposal, get an e‑signature, and invoice in one flow. Use this method today and cut callbacks tomorrow.