Every month, the water bill tells you exactly how much you spent. It never tells you why.

That's the real cost of an undetected leak. Not just the gallons — the fact that the number shows up with no address. No unit, no fixture, no start date. Your team can't fix a total. So the waste keeps running, the next bill looks the same, and water quietly becomes a line item that's "just what this building costs."

Let's put numbers on it, then look at what it costs to find.

One toilet, one year

The EPA estimates that a running toilet can waste 200 gallons a day or more. At the water and sewer rates a Kansas City owner paid in our Stonewood case study — $5.50 per HCF for water and $10.85 for sewer — that single toilet costs about $4.37 a day, $131 a month, or $1,600 a year.

1 HCF = 748 gallons. Your rates will differ — and sewer often costs more than the water itself.

That's a modest leak. A severe one can waste $65 a day or more. Now think about how many toilets, faucets and showers are in your portfolio, and how long any one of them could run before someone noticed.

Why the waste lasts so long

Nobody is hiding it. It's just that the people who could spot it aren't the people who pay for it. A resident may hear a toilet refilling at night, but it doesn't bother them enough to report. Management and maintenance never hear it. By the time the bill arrives, the leak has been running for weeks, and the bill can't point to it anyway.

And leaks are only part of it. Overuse and high-flow fixtures raise the bill the same way. They just need a different fix: a leak needs a repair, overuse needs a conversation with the resident.

What finding it costs

Leak detection pricing depends on what you're buying.

A plumber or leak specialist is billed per visit. You get the location of a leak you already suspect — and nothing after they leave.

Moisture sensors and shutoff valves are priced per device, sometimes with a subscription. They protect against floods near each sensor. Silent waste goes down the drain without ever touching one.

Main-meter monitoring is a device plus a subscription. It tells you the building is using more water, not where.

Fixture-level water intelligence, like DrizzleX, is a one-time hardware cost — per fixture, or per unit for a full install — plus a monthly subscription per unit, priced per property. You get leaks, overuse and high-flow fixtures flagged by unit and fixture, alerts ranked by cost, and proof on the city bill.

Two buildings, real numbers

Stonewood Apartments, Kansas City. 87 units in a 1973 garden-style property. The owner monitored toilets only, to keep up-front cost low: $3,874 in hardware and $435 a month. Consumption fell about 33% in the year after installation, and the system broke even in roughly two months. That payback is fast because of Kansas City's high sewer rates and the toilets-only scope.

Customer 394, Los Angeles. 182 units, all fixtures monitored. $40,950 in hardware and $1,092 a month. Consumption fell about 34% over six months, and the system broke even in about eight months.

Across our case studies, payback has run 2 to 8 months, with consumption down 33–44%.

Where it shows up: NOI

Operating expenses reduce net operating income, and water and sewer is one of the few operating lines you can cut without touching rents or services. The city sets the rates. You can't control the rates — but you can cut the waste.

Here's why that matters to an asset manager. At a 5% cap rate, every $1 of annual expense prevented adds about $20 of building value. Stonewood's net savings of $20,087 a year in years two through ten work out to roughly $400,000 in building value at a 5% cap rate — and about $197,000 in net savings over the ten-year hardware life, assuming flat water rates.

None of that is a rebate. It's water you stop paying for. The money never leaves your bank.

One catch: it only lasts while you're watching

Flappers wear out. Valves stick. New residents move in. New leaks start every month, so consumption stays down only while monitoring continues and your team keeps fixing what it finds. Stop watching, and a building drifts back to its old bill.

There's a second reason to keep watching. Slow leaks behind walls and under sinks don't stay slow forever. Caught early, they're a work order. Caught late, they're drywall, flooring and an insurance claim. More on the methods in our leak detection guide.

Find out what your buildings are losing

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