Hidden Leak Location
Locating leaks behind finishes, under slabs and inside ceilings before any demolition, so the repair is a repair rather than an exploration.
Plumbing
Leak Detection & Repair On Long Island
We find the leak before we open the wall. NJM locates and repairs hidden leaks for Long Island homes and businesses with the right equipment and no unnecessary demolition — 24/7 across Nassau and Suffolk County.
HIDDEN LEAKSNO GUESSWORKSAME-DAY SERVICE24/7 EMERGENCY
Licensed & Insured
Master Plumber
TASK 86/87 Certified
Navien NSS Certified
22+ YEARS ON LONG ISLANDGet Your Free Estimate
LICENSED & INSURED · NASSAU & SUFFOLK
PLUMBING · HEATING · COOLING · CONTRACTING
Have An Emergency? We’re Available 24/7.
631-587-0085WE ANSWER EVERY CALLPlumbing
Finding The Leak Before We Open The Wall
A leak you can see is a plumbing job. A leak you cannot see is a race — every day it runs, it is soaking framing, insulation and drywall that will cost more to repair than the pipe ever did. NJM locates and repairs hidden leaks across Nassau and Suffolk County, and the priority is always finding the exact spot before anything gets cut open.
That matters most in finished spaces. A tiled bathroom, a finished basement or a plaster ceiling is expensive to put back, and the difference between a contractor who locates a leak properly and one who opens the wall in three places looking for it is measured in thousands. Licensed Master Plumber on staff, 24 hours a day, every day of the year.
24/7 Emergency ServiceLicensed & Insured
Master PlumberLicensed to pull permits
TASK 86/87Certified for gas work
Navien NSSFactory-trained on tankless
22+ years on Long Island · Plumbing, heating, cooling, gas and contracting under one roof
What We Do
Leak Detection & Repair Services
Slab Leaks
Leaks in lines running beneath concrete. Located and either repaired or rerouted depending on which makes more sense for the house.
Supply Line Repair
Repairs and replacement of leaking supply lines, including the galvanized runs that eventually fail in post-war Long Island housing.
Pinhole Leaks In Copper
Copper develops pinholes with age and water chemistry. A single pinhole is usually the first of several, so we assess the run rather than patching one spot.
Fixture & Valve Leaks
Leaking valves, supply stops, traps and fixture connections — the small ones that quietly ruin a cabinet base.
Service Line Leaks
Leaks between the meter and the house, which show as a permanently damp yard and a rising bill.
Emergency Response
Active leaks answered 24 hours a day, every day of the year. Shut the main off and call.
Repair, Not Just Detection
We find it and we fix it. There is no second contractor to arrange once the leak is located.
Plumbing — before you call
Two kinds of visit. You’ll know which before we come.
We don’t charge to quote a job. We do charge to find a problem nobody has identified yet. Which one you need — and what it costs — gets agreed on the phone, so nothing about the cost is a surprise on the doorstep.
The rate you are told is the rate
You get the number on the phone, before anyone is dispatched, and it is what you are charged when the technician arrives. One rate across all four trades — plumbing, heating, cooling and gas.
What it pays for
A licensed, insured technician carrying the certifications the work needs, and the time to find what has actually failed — not a quick look and a guess.
Watch for the bait and switch
A call-out advertised at almost nothing gets recovered once someone is standing in your basement. Get the number before anyone travels — from us, or from anyone else you call — and hold them to it when they arrive.
Financing on larger jobs
A boiler that fails in January is not a purchase anyone planned. Financing is available on the big-ticket work, so a system replacement does not have to come out of savings in one go.
What it is normally used for
Boiler, furnace and water heater replacement, a full air conditioning system, a whole-house repipe, sewer and water main work, and larger contracting jobs — kitchens, bathrooms, dormers and extensions.
When to bring it up
At the estimate, before anything is scheduled. It is worth asking even if you think you will not need it, because knowing it is there changes what you are willing to consider fixing properly.
What it does not change
The price of the job. The quote is the quote whether you finance it or not — and on a straightforward repair it is usually not worth the paperwork. We will tell you which one you are looking at.
Financing provided throughSynchronyCredit is extended by Synchrony. Subject to credit approval.
Call 631-587-0085Not sure which one you need? Call and describe it — we will tell you before we book anything.
How Leaks Show Up
Signs You Have A Hidden Leak
Most hidden leaks announce themselves long before water appears. These are the signals worth acting on.
Water Bill Jumped
A sudden increase with no change in usage is the clearest early sign. Turn every fixture off and watch the meter — if it is still moving, water is going somewhere it should not.
Pressure Has Dropped
Falling pressure across the whole house can mean a leak in the supply line, though in older Long Island homes it just as often means galvanized pipe corroding closed. Worth diagnosing before assuming either.
Stains On Ceilings Or Walls
A brown ring or a soft patch means water has already been travelling for a while. The stain is rarely directly below the leak — water runs along framing before it drops.
Musty Smell With No Source
Persistent damp smell in a basement, closet or under a cabinet usually means moisture is feeding something. Smell often arrives before any visible mark.
Warm Spot On The Floor
A warm patch underfoot can indicate a hot water line leaking beneath a slab. This one is worth calling about quickly, because slab leaks do not improve with time.
Sound Of Running Water
Water audibly moving when every fixture is closed. Easiest to hear at night, and one of the more reliable indications of a live leak.
Cracked Or Lifting Flooring
Tile lifting, wood cupping or vinyl bubbling with no spill to explain it usually means moisture from underneath.
Foundation Or Yard Damp
A permanently wet patch of yard or damp foundation wall in dry weather can mean the service line between the meter and the house is leaking.
More Plumbing Services
Everything We Handle In Plumbing
One licensed team, one number to call, across Nassau and Suffolk County.
Current Offers
Money Off, Plainly Stated
What it says on the coupon is what comes off the bill. Mention it when you call.
$50 Off
Leak Repair
Found the leak or still looking for it — fifty dollars off putting it right.
Code NJM-LEAK50Expires October 31, 2026See the details →$50 OffYour First Service Call
New to NJM? Fifty dollars off the first time we come out — one licensed team for plumbing, heating, cooling and gas.
Code NJM-FIRST50Expires October 31, 2026See the details →Common Questions
Frequently Asked Questions
How can I tell if I have a hidden leak?
Turn off every fixture and appliance that uses water, then look at your water meter. If it is still registering flow, water is going somewhere. A jump in the bill with no change in usage is the other reliable indicator. Stains, musty smells and dropping pressure usually mean it has already been running a while.
What should I do right now if water is actively leaking?
Shut off the main water valve to the house — usually where the service line enters, often near the meter or water heater. Then call 631-587-0085. Stopping the flow limits the damage far more than anything else you can do in the first hour, and we answer 24 hours a day.
Will you have to tear up my walls or floor?
That is exactly what we work to avoid. Locating the leak precisely first means opening one spot rather than several. In a tiled bathroom or a finished basement the cost of putting the space back can exceed the plumbing repair, so it is worth doing properly.
What is a slab leak?
A leak in a water line running beneath a concrete slab. Common signs are a warm patch on the floor, unexplained damp, or the sound of running water with everything turned off. Depending on the house, the fix is either a targeted repair or rerouting the line above the slab — we will explain which makes sense.
My pressure dropped. Is that a leak?
Sometimes, but in older Long Island homes it is just as often galvanized supply pipe corroding closed from the inside. Those need very different fixes — a repair versus a repipe — so it is worth diagnosing rather than guessing.
I found one pinhole in a copper pipe. Just fix that spot?
We can, but be aware that a pinhole is usually the first of several. Copper that has thinned enough to perforate in one place has generally thinned along the run. We will tell you honestly whether a spot repair is realistic or whether you are going to be calling us back.
Do you handle leaks in commercial buildings?
Yes — offices, restaurants, retail and multi-family properties across Nassau and Suffolk County, with the same 24/7 response.
Are estimates free?
Yes, free and with no obligation. Call 631-587-0085, or use the form on this page and we will be in touch within 24 hours.
Service Area
Proudly Serving Long Island and Surrounding Areas.
Based in North Babylon, working across both counties — close enough to get there fast, local enough to know the housing stock and the permit offices.
Find Plumbing Services Near You!
- Long Island
- Nassau County
- Suffolk County
Towns We Serve
- North Babylon
- Babylon
- West Babylon
- Deer Park
- Lindenhurst
- Farmingdale
- Massapequa
- Hicksville
- Dix Hills
- Commack
- Islip
- Hempstead
- North Hempstead
- Rockville Centre
Proudly serving all of Nassau and Suffolk County, with deep local roots near our North Babylon home base.
Get A Free EstimateWhat Long Island Says
Reviews From Homes & Businesses We've Served
5 out of 5 stars
Neil came first thing in the morning with a late night. Call on an emergency really took care of us one of the best guys out there. Awesome camera system found everything we needed and was able to fix the same day 5star company
Jason Z.October 2024
5 out of 5 stars
Our experience with NJM mechanical and contracting company was excellent. Neil fixed our shower leak. He was efficient and personable. We would highly recommend using them. Thank you Neil.
Linda LevinsonJanuary 2024
5 out of 5 stars
leaking elbow on a baseboard radiator great job very professional checked leak all good.
Filippo GranittoFebruary 2022
Need Leak Detection & Repair?
Free estimates with no obligation, 24/7 emergency response, and 22+ years serving homes and businesses across Nassau and Suffolk County.