Finding the Leak
Poly B Leak Detection: How a Hidden Leak Actually Gets Found
Not every Poly B leak announces itself with visible water. Here's how leak detection actually works when the problem is hidden behind a wall, under a slab, or inside a ceiling.
A slow leak behind a wall can cause real water damage long before it becomes visible — catching it early matters.
Get your Poly B repair quote
Suspect a hidden leak? A referral to a licensed contractor includes checking for it.
We’ll email you to connect you with a licensed plumbing contractor, who confirms your Poly B on site and gives you a firm price — pipe and walls, one number.
Firm, written price before any work begins — no surprise billing, ever.
Why It's Not Always Obvious
Why Poly B Leaks Aren't Always Visible
A leak inside a wall cavity, under a slab, or in a ceiling void doesn't always show up right away as a visible stain or puddle. Water can travel along framing or insulation before it surfaces somewhere else in the house, which makes the visible sign a poor guide to where the actual leak is.
That's the core challenge with leak detection — confirming there IS a leak is often easier than confirming exactly WHERE it is, especially in a Poly B system where the failure is typically at a fitting or joint you can't see.
How It's Actually Done
How Professional Leak Detection Works
Pressure testing is one of the most reliable methods — isolating sections of the system and checking whether they hold pressure tells us which run has the problem, without opening walls speculatively. Moisture readings and visual inspection of accessible areas (basements, crawlspaces, around fixtures) narrow it further.
The goal is always to confirm the location with real evidence before cutting into a wall — not guess-and-check, which just adds unnecessary drywall repair on top of the plumbing fix.
What We Do With It
What Happens Once a Leak Is Located
Once we've confirmed where the leak is, we open only the access point needed to make the repair or, if it's part of a broader assessment, to evaluate the surrounding pipe. See our process page for how that access work fits into a whole-home repipe.
If the leak turns out to be one symptom of a wider issue — which is common with Poly B, since the whole system ages together — we'll tell you honestly rather than just patch the one spot and move on.
Signs Worth a Detection Visit
When It's Worth Booking a Leak Detection Visit
A few signs are worth acting on before there's an obvious puddle.
A jump with no obvious new usage often points to a hidden leak somewhere in the system.
Can indicate slow moisture building inside a wall or ceiling cavity — see signs of Poly B failure.
A leak diverting water from your fixtures can show up first as reduced pressure, not visible water.
Getting Started
Book a on-site Check
If you suspect a hidden leak, a referral to a licensed contractor includes checking for it as part of confirming your Poly B condition overall — no guesswork, no unnecessary wall-opening.
DIY Checks vs Professional Detection
What You Can Check Yourself First
Before booking a professional visit, a few simple checks can help: note your water meter reading, avoid using any water for a couple of hours, then check the meter again — movement with no water use suggests a leak somewhere in the system.
That kind of check confirms there's likely a leak, but pinpointing the location is where professional pressure testing and moisture inspection genuinely add value over guesswork.
If your water bill check suggests a leak but you can't get an appointment right away, it's still worth knowing where your main shut-off is in case the situation escalates before your assessment — a small precaution that costs nothing and could limit damage if things change quickly.
Common Questions
Frequently Asked Questions
How do you find a leak that isn't visible?
Primarily through pressure testing sections of the system and moisture inspection in accessible areas, confirming the location with evidence before opening any wall. Catching that kind of pattern early, before it becomes a visible stain or a pressure problem, is exactly why an unusual water bill is worth investigating rather than dismissing as a billing error.
Can a hidden leak cause damage before I notice it?
Yes — water can travel inside a wall cavity for a while before surfacing, which is why an unexplained water bill increase or musty smell is worth checking even without visible water.
Will you have to cut into my walls to find the leak?
Only the access point needed once the location is confirmed — we don't cut speculatively. We'd rather spend the extra time confirming the real location than risk opening the wrong section of wall.
Is leak detection included in a Poly B assessment?
Yes — if you mention a suspected leak when booking, we'll check for it as part of the on-site visit. We'll explain our findings clearly either way.
What if the leak turns out to be part of a bigger Poly B problem?
We'll tell you honestly rather than just patch the one spot — most single leaks in a Poly B system aren't isolated events. We'd rather confirm it properly with real testing than have you second-guessing whether the repair actually addressed the right spot. We'll walk you through exactly what we find.
How do you find a water leak behind a wall?
A water leak behind wall cavities gets found by narrowing rather than guessing - moisture meters, thermal imaging and pressure testing say where to open before anything is cut. That is the difference between one small opening and a wall full of them.
In Short
Poly B Leak Detection — The Short Version
Poly b leak detection relies on pressure testing and moisture inspection to confirm exactly where a hidden leak is before any wall gets opened — not guesswork. If you're seeing signs like an unexplained water bill jump or a musty smell with no visible source, a referral to a licensed contractor checks for a hidden leak as part of evaluating your Poly B overall. Whether you've noticed a specific sign or just want peace of mind, a professional check costs you nothing to book and can catch a real problem well before it becomes an emergency repair or a water-damage situation.
Get Started
Suspect a Hidden Leak?
A referral to a licensed contractor includes checking for it — no guesswork, no unnecessary wall damage.
Get My Poly B Repair Quote