# A Slab Leak in a 1970s Mesa Ranch - Acoustic Detection, Two-Hour Repair | Comfort Pros Blog > Warm spot on the tile floor, water bill that doubled in a month, no visible leak. Acoustic detection found the break under the slab in 90 minutes - trenchless spot repair finished the same day. URL: https://www.comfortprosaz.com/blog/mesa-slab-leak-acoustic-detection/ Last-Modified: 2026-08-22 Author: Mike V. Case Study # A Slab Leak in a 1970s Mesa Ranch - Acoustic Detection, Two-Hour Repair Warm spot on the tile floor, water bill that doubled in a month, no visible leak. Acoustic detection found the break under the slab in 90 minutes - trenchless spot repair finished the same day. Mike V. · August 22, 2026 · 5 min read ![East Valley single-story home with a bare concrete patio, representing a Mesa slab-on-grade ranch where acoustic detection located an under-slab leak](/images/featured/candid-photo-of-a-chandler-single-story-tract-home.webp) Marcus T. called from a 1970s slab-on-grade ranch in East Mesa on a Tuesday morning. The water bill had gone from $47 to $112 in two months. There was a warm spot on the tile floor near the hallway bath that nobody had stood on bare-foot in a while. No visible leak anywhere. This is the call we get most often out of Mesa’s slab-on-grade housing stock from the late 1960s through the early 1980s. The original copper repipe has had forty-plus years of Phoenix hard water moving through it, and a pinhole develops in the hot-water line under the slab. The water surfaces where it finds a path - through a crack in the concrete, along the path of least resistance to a tile grout line. ## Why a Visual Inspection Wasn’t Enough Marcus had already had a different plumber out. That plumber ran the meter test (turn off everything in the house, watch the meter, confirm the leak is on the house side), then walked the floors with a thermal camera, and gave a quote that said “find and repair” without telling Marcus where the leak actually was. A thermal camera sees temperature differentials through the slab. It finds the hot spot, which is what we already knew. What it does not do is pin the location precisely enough to open one hole. If you open the slab in the wrong spot, you are jackhammering the floor looking for a leak that is two feet to the left. ## What Acoustic Detection Does That a Thermal Camera Doesn’t Acoustic detection uses ground microphones and headphones to listen for the hiss of pressurized water escaping a pipe under pressure. The signal is unmistakable once you have heard it - a high-frequency hiss that gets louder as you walk the probe closer to the break and softer as you walk away. The leak Marcus had was a 1/8-inch pinhole in the hot-water line under the hallway bath, and we located it inside a 12-inch radius in 90 minutes. The pinhole was at the point where the original copper line crossed a control joint in the slab - a textbook failure point. The pipe had been rubbing against the slab edge for forty-odd years, the protective coating was gone, and the water did the rest. ## The Repair We opened one hole, two feet by two feet, directly over the break. The copper was visibly green at the failure point. We cut back to clean copper on either side, sweated in a new section with lead-free solder, and pressure-tested the line at 80 PSI for 15 minutes before we closed the slab back up. The tile came out clean. We replaced the two tiles we removed with new ones from Marcus’s garage stash - he had leftover tile from the original install, which is not unusual in homes this age. New concrete patch, tile grout, job done. Total time on site: about four hours, including the detection work. ## What the Bill Looked Like Marcus had a written flat-rate quote before we opened any tile. The number on the quote was the number on the invoice. | Line item | What it was | | --- | --- | | Acoustic leak detection | 90 minutes on site, locator, ground mic | | Slab access | One hole, two feet by two feet | | Copper repair | New section, lead-free solder, pressure test | | Concrete patch | New patch in the opened hole | | Tile replacement | Two tiles from homeowner’s leftover stock | | Permit | City of Mesa plumbing permit (required for any under-slab work) | The line items we did not include: diagnostic fee on top of the detection charge. Camera-in-the-line sales pitch. Replacement of the entire repipe. Pressure-reducing valve upsell. The quote was the quote. ## What Happens If You Don’t Catch It Marcus had been paying the high water bill for two months before he called. At the rate his slab leak was running, he was losing roughly 60 gallons per day into the foundation. That is not catastrophic in the short term, but a slab leak left alone for six months does two things you do not want: it undermines the soil under the slab in a localized spot, which causes settling cracks in the walls, and it keeps the surrounding concrete and framing perpetually damp, which invites termites - which are a much more expensive problem than a plumbing repair in Mesa. If you have a warm spot on the tile floor or a water bill that suddenly doubled without explanation, the meter test is two minutes of your time and it tells you whether the problem is on your side of the meter. If the meter confirms a leak, acoustic detection is the fastest path to one hole instead of three. **If you suspect a slab leak in Mesa or anywhere in the East Valley** - request a slab leak diagnostic [/emergency-plumbing/ →](/emergency-plumbing/) or read more about the signs of a slab leak [/guide/signs-of-a-slab-leak/ →](/guide/signs-of-a-slab-leak/) . ![Mike V.](/images/squares/author-mike-v.webp) Mike V. [/about/#mike-v →](/about/#mike-v) Licensed Master Plumber - California Licensed master plumber covering Los Angeles County slab leaks, repipes and water heaters. ✓ CSLB Licensed Team Member #plumbing #slab-leak #mesa #acoustic-detection #trenchless ## More From the Trucks ![Interior of a 1962 California bungalow with original plaster walls, representing a Burbank home where three pinhole leaks in eighteen months led to a whole-home PEX-A repipe](/images/misc/interior-of-a-pre-1960-california-bungalow-with-a-.webp) Case Study Sep 12, 2026 ### A 1962 Burbank Bungalow, On Its Third Pinhole in Eighteen Months - The Whole-Home Repipe We Did in PEX-A Three pinhole leaks in galvanized and soft copper in eighteen months. The fourth one was already forming. We repiped the whole house in PEX-A in four days, with the drywall patched back better than it was. Read the story [A 1962 Burbank Bungalow, On Its Third Pinhole in Eighteen Months - The Whole-Home Repipe We Did in PEX-A →](/blog/burbank-whole-home-repipe-pex-a-1960s-copper/) ![A wall-mounted ductless mini-split head installed high on a stucco wall above a garage workbench, with a slim white line-set cover running down to the outdoor unit](/images/featured/wall-mounted-mini-split-head-above-a-garage-workbe.webp) Case Study Sep 10, 2026 ### Adding AC to a La Crescenta Casita - A Ductless Mini-Split in One Day A converted garage casita in the Crescenta Valley foothills had no AC, no ductwork, and a tight electrical panel. A single-zone ductless mini-split solved all three - installed in one day, no drywall opened. Read the story [Adding AC to a La Crescenta Casita - A Ductless Mini-Split in One Day →](/blog/la-crescenta-ductless-mini-split-casita/) ![A restored Pasadena driveway and front yard after a trenchless sewer liner was installed, showing that no excavation was needed for the sewer repair](/images/hero/restored-driveway-and-landscaping-after-a-trenchle.webp) Case Study Sep 10, 2026 ### Pasadena Sewer Lateral: We Lined 48 Feet of Pipe Under a 50-Year-Old Driveway Without Digging A 1968 clay sewer lateral with root intrusion at every joint. The homeowner was told she needed a $22,000 excavation. Cured-in-place lining sealed every joint from the inside and saved the driveway. Read the story [Pasadena Sewer Lateral: We Lined 48 Feet of Pipe Under a 50-Year-Old Driveway Without Digging →](/blog/pasadena-sewer-lateral-cured-in-place-lining/) ![Comfort Pros HVAC technician greeting a homeowner at the front door](/images/hero/candid-wide-photo-of-a-technician-shaking-hands-wi.webp) Same-day appointments available ## Ready for an Honest Number? Run a real load calculation online, or call the team in your state. Flat-rate pricing either way, and nobody shows up to sell you something bigger than you need. Get Your TrueQuote [https://quote.comfortprosaz.com →](https://quote.comfortprosaz.com) (480) 435-2334 [tel:+14804352334 →](tel:+14804352334) Flat-rate pricing, no upsells Parts and labor warranty Licensed in AZ and CA California team: (818) 690-7951 [tel:+18186907951 →](tel:+18186907951) · Text us: (818) 489-2826 [sms:+18184892826 →](sms:+18184892826)