Cutaway illustration of an interior wall with a copper pipe spraying from a pinhole leak, wet framing, and stains spreading on the drywall and the ceiling below

WALL · Inside the walls · Coon Rapids & north metro

Leak detection, before the walls come down.

AP Plumbing finds hidden plumbing leaks in Coon Rapids and north-metro homes: inside walls, under floors, above ceilings and on the main line. We narrow it down with the meter, pressure tests and tools like thermal imaging and acoustic listening, then open only what we need to and fix it.

Call (612) 245-7341 Signs of a hidden leak

5.0 · 513 Google reviews

What you’re looking atA pinhole leak inside a wall

Pinhole leak
Copper can develop pinhole leaks that spray inside the wall for weeks before anything shows. The first sign is often a stain somewhere else.
Joints & fittings
Elbows, couplings and connections are common leak points, especially near fixtures that heat and cool many times a day.
Wet stud & bottom plate
Water runs down the framing and pools at the bottom plate, so the damage shows up lower than the leak itself.
Stain on the drywall
Stains spread out from the wet spot, so the leak usually sits above or beside the stain rather than right behind it.
Ceiling below
A leak in an upstairs wall or floor often shows up first as a ceiling stain one floor down.
Wet insulation
Insulation soaks up water, holds it against the wood and hides the leak from view.

01The short answer

Find it first. Then open the smallest hole possible.

In one paragraph

Hidden leaks show up as stains, musty smells, warped floors, or a water bill that jumps for no reason. The water meter tells you whether water is moving when nothing’s on. From there it’s narrowing down: which line, which room, which few inches of wall.

EPA’s numbers are why it matters: the average household’s leaks waste more than 9,300 gallons a year, and about nine percent of U.S. homes have leaks wasting 50 gallons or more a day. Inside a wall, that water also goes into wood and insulation.

Check your meter first

EPA’s test: read the water meter, use no water for two hours, then read it again. If the number changed, something is leaking. In winter, a family of four using more than 12,000 gallons a month likely has a serious leak.

How we narrow it down

Meter readings and pressure tests to confirm a leak and separate hot from cold
Shutting off sections of the system to isolate it
Thermal imaging and acoustic listening to pinpoint the spot in a wall or floor
A camera when the suspect is a drain or sewer line
Opening the smallest area that gets to the leak

Not every “leaking” water heater is

A.O. Smith notes that many water heaters suspected of leaking aren’t leaking tanks: condensation, a loose fitting or the relief valve is often the source. Worth checking before replacing anything.

02Symptoms

Signs you have a leak you can’t see.

Hidden leaks give themselves away. Here’s what to look for and how fast to act.

Leak detection: what you notice → what it usually means
What you notice	What it usually means	How soon to call
New stain on a ceiling or wall	A supply or drain leak above or beside it, often under a bathroom.	Today
Water bill jumped for no reason	A running toilet, a dripping fixture or a hidden supply leak.	This week
Meter moves with everything off	Water is leaking somewhere on the house side of the meter.	Today
Musty smell, or soft or warped flooring	A slow leak that has been wetting the framing for a while.	This week
Sound of running water when nothing is on	A supply leak in a wall or under a floor, or a running toilet.	Today
Water dripping from a ceiling or light fixture	Shut off the main water valve and stay away from wet electrical fixtures, then call.	Right now

03Minnesota field notes

What leaks cost, by the numbers.

Rules and numbers that apply to homes here, each with its source.

Per household
9,300 gal
The average household’s leaks waste more than 9,300 gallons of water a year.
Source: EPA WaterSense, Fix a Leak Week
Big leakers
9%
About nine percent of U.S. homes have leaks wasting 50 gallons or more per day.
Source: EPA WaterSense, Fix a Leak Week
Meter test
2 hours
Read the meter, use no water for two hours, and read it again. Any change suggests a leak.
Source: EPA WaterSense, Fix a Leak Week
Winter check
12,000 gal
A family of four using more than 12,000 gallons a month in January or February likely has a serious leak.
Source: EPA WaterSense, Fix a Leak Week
On the bill
~10%
Fixing easily corrected household leaks can save homeowners about 10 percent on their water bills.
Source: EPA WaterSense, Fix a Leak Week
False alarms
Check first
Many water heaters suspected of leaking aren’t leaking tanks: condensation, loose fittings or the relief valve are often the source.
Source: A.O. Smith gas water heater installation & care guide

Checked October 2026. Codes and city rules change; your permit office has the final word.

04Real work

The leak nobody else could find.

AP Plumbing job photo: drain stack repair through the ceiling below a bathroom — **Job photo**Drain stack repair through the ceiling below a bathroom

Denis did an amazing job solving my mystery plumbing leak after water started dripping from our ceiling!! He was knowledgeable, detailed, prompt and thoughtful AND found 3 different issues no one else had found in prior visits.

Terry S.Google review · Jun 2024

“I had an unfortunate surpise pinhole leak that was between my main floor and basement … A short time later, the problem was solved, area cleaned up and he showed me the fix.”
Lallee Y. · Google review · Aug 2026
“We had an emergency water leak coming from our kitchen sink that went into our basement. We contacted them around 9:30 pm, and they came out same night. They found the problem immediately and fixed it same day.”
Alysa A. · Google review · Jun 2025
“Denis was incredibly responsive and was able to get to my house within just a few hours of calling, which was especially appreciated since I was concerned about water leaking into the wall. … He was upfront and transparent about pricing, clearly explaining what we could try that day versus what would ultimately need to be done if those attempts didn't work. No surprises, no pressure, just honest and knowledgeable service.”
Janell P. · Google review · Oct 2026

Leak detection questions, answered.

Straight answers, with the source when a rule or number is involved. Still not sure? Call and describe it.

Call (612) 245-7341

How do I know if I have a hidden water leak?

Look for a new stain on a ceiling or wall, a musty smell, warped flooring, the sound of running water when nothing is on, or a water bill that jumps for no reason. Then do EPA’s meter test: read the meter, use no water for two hours, and read it again. Any change means a leak.

Source: EPA WaterSense, Fix a Leak Week

How do plumbers find leaks without tearing out walls?

By narrowing it down before opening anything: meter readings and pressure tests confirm the leak and whether it’s on the hot or cold side, shutting off sections isolates it, and thermal imaging and acoustic listening help pinpoint the spot. Then only the area over the leak gets opened.

Is a leak inside a wall an emergency?

If water is dripping from a ceiling, light fixture or wall, yes: shut off the main water valve, stay clear of wet electrical fixtures and call. A slow leak can wait a day, but the damage grows the longer framing and insulation stay wet.

How much water can a hidden leak waste?

EPA says the average household’s leaks waste more than 9,300 gallons a year, and about nine percent of homes have leaks wasting 50 gallons or more every day. Fixing easily corrected leaks saves about 10 percent on the water bill.

Source: EPA WaterSense, Fix a Leak Week

Who is responsible for a leak on the water line outside my house?

In Coon Rapids, the city is responsible for the water main and the service lateral up to the curb stop shutoff in your yard. Everything from the curb stop to the house is the property owner’s, so a leak there is the owner’s repair.

Source: City of Coon Rapids, “Keep the Water Flowing” (Jan. 2026)

06Related

Often the same visit. Often the same wall.

Same service, every stop on the line

Each city page has that city’s own water report numbers, permit rules and sewer-line responsibilities.

07Call us

Call the people who know your house inside out.

(612) 245‑7341

Mon – Sat · 8 AM – 10 PM

Hours: Monday – Saturday, 8 AM – 10 PM · Sunday closed
Address: 12433 Uplander St NW, Coon Rapids, MN 55448
Serving: Coon Rapids and 14 north‑metro cities · see the map