Apartments & multi-family
Apartment and multi-family leak detection
One master meter, a hundred near-identical units, and consumption that climbed before anybody reported a thing. Finding which stack, which line and which slab.
How it announces itself
The meter moved before anything else did

On a multi-family property the leak almost never arrives as a phone call. It arrives as consumption. Nobody in a hundred units can hear a supply line weeping under a breezeway slab, and the water goes into the ground rather than onto a floor, so the first symptom is a master-meter reading that no longer matches how the property is being lived in.
The night flow reading
The most useful number on an apartment property needs no equipment. Read the master meter late, when the property is as quiet as it gets, and again early before anyone is up. Almost no legitimate use should happen in between. A property that keeps consuming through that gap is losing water, and the size of the gap tells us whether we are looking for a weep or a break. Do it on two different nights if you can: one reading is a number, two are a trend, and a trend is what makes an owner's approval straightforward.
Why this lands on rental property first
Rental-dense parts of the Valley are where the pattern shows up, because that is where the multi-family stock is. Census figures put owner occupancy in Tempe at about 42 percent of occupied homes, with single-family houses making up only about 39 percent of the housing units there; in the ZCTA5 85007 area north-west of downtown Phoenix owner occupancy is about 44 percent. Those are properties where one meter and one maintenance team sit between a buried pinhole and the person who has to approve digging.
Source: U.S. Census Bureau, American Community Survey 5-year estimates (2023)
Method
Identical units are an advantage, not a problem
Near-identical floor plans mean the pipe takes the same route in every one of them.
Read the master meter with the property quiet
Establish that water is genuinely leaving the system before anyone knocks on a door.
Take the non-unit consumers out of the picture
Irrigation, the pool make-up line and the laundry room are the three biggest users on the property that have nothing to do with any resident, and each isolates at an existing valve.
Work by stack and riser, not unit by unit
The line that failed in 112 runs the same way in 212, so testing a riser answers for every unit on it and turns a hundred doors into a handful of tests.
Use the units you can already get into
Vacants, ground floor and the resident who called are usually enough to isolate and hold a stack; the rest of the building never needs to be entered.
Pressure-test the stack, then listen
A stack that holds is eliminated in writing; on the one that does not, acoustic listening and line tracing put the loss at a point.
Confirm it before a saw comes out
The location is marked and photographed with the unit number in frame, so the work order, the locate and the photograph all agree.
On site
Access is the long pole, not detection
Notices, work schedules, dogs and residents who would rather nobody came in are what make these jobs take a week — not the searching.
Give us the stack we suspect and we will name the exact units needed, so notices go out once. Where we do go in, we explain what we are doing to the resident, in English or Spanish, and nothing about the rest of the property.
The quiet places
Water where nobody lives
Much multi-family loss is nowhere near a resident:
- Common-area irrigation. Longest buried run on the property, runs before dawn, and a mainline break performs for an empty parking lot.
- The pool and spa. An autofill hides a leaking vessel or return line indefinitely, and the loss simply lands on the master meter.
- The laundry room. Supply lines under a slab in a room where a damp floor is not remarkable.
- Hose bibs and exterior runs, especially where a parking lot has been resurfaced or a building added.
- Breezeways and stair landings. A slab leak here shows as efflorescence on stucco one or two units along, which is why the wet wall is so often not above the pipe.
The work order says unit; the leak says stack
Your system wants a unit number and a resident's complaint is attached to one. The plumbing does not work that way. Our locate gives you both — the unit where water is showing and the riser or slab run it belongs to — so the repair is scoped once instead of chased door to door.
What we are likely doing on your property
Where we work
Rental-dense parts of the Valley we work in
Pick your part of the Valley for what is particular about the ground under it.
Straight answers
What on-site and regional managers ask
Consumption climbed and not one resident has reported anything. Is that possible?
It is the normal case. Slab and irrigation leaks on a multi-family property send water into the ground, not onto a floor, and a night meter reading with the property quiet will usually confirm it in one evening.
Do we have to notice every unit in the building?
No. Tell us the plan type and we work by riser, then name the specific units needed to isolate the suspect stack — often only vacants and ground floor. You send notices once, for a single window.
Can you tell us whether it is the plumbing or how somebody is using water?
Yes, and it is one of the more useful outcomes. An isolated stack that will not hold pressure with every fixture shut is plumbing, and that distinction keeps the conversation with a resident short and civil.
Can the pool, the laundry and the leasing office stay open?
Almost always. The measuring and listening happen with the property running normally, and the pressure test needs one isolated section briefly, in the quietest window you have.
Send us the meter reading and the unit number
A photo of the master meter, the wet wall or the equipment pad and one sentence about what changed is enough to start narrowing it down.