When a commercial water bill spikes, check the meter after hours to confirm whether water is flowing when the building is closed, then work through restroom fixtures, kitchen and process equipment, cooling towers and HVAC makeup water, irrigation, and the underground service line. If the meter moves after hours and nothing visible explains it, professional leak detection finds the hidden source.
- After-hours meter reading is the fastest leak test for a business.
- Flush valves, urinals and faucets in restrooms are frequent culprits.
- Equipment with water makeup lines can run nonstop if a valve fails.
- Separate irrigation and fire lines when testing.
Step 1: Confirm With an After-Hours Reading
Read the meter when the building closes and again before it opens, with no scheduled irrigation or equipment running overnight. Any usage points to a leak or something running that shouldn't be. For a quick check, watch the meter's low-flow indicator for 15 minutes during closed hours. If your property has multiple meters, such as domestic, irrigation and fire, check each separately.
Step 2: Restrooms
- Flush valves that don't close fully or run on
- Urinals with stuck or misadjusted valves
- Tank toilets with leaking flappers
- Faucets with worn cartridges or failed sensors that keep running
- Leaks under sinks and at supply stops
Step 3: Kitchens and Equipment
Restaurants and food businesses have many water-using appliances: ice machines, dishwashers, pre-rinse sprayers, steamers, combination ovens and water filters. A failed valve on any machine with an automatic fill can run continuously. In other businesses, look at process equipment, wash bays, water heaters, and any equipment with a makeup water line.
Step 4: HVAC and Cooling
Cooling towers and some HVAC systems use makeup water. A float valve stuck open or a leak in the system can send water to drain constantly. Chilled water and hydronic systems in larger buildings can also leak. See chilled water leak detection.
Step 5: Irrigation and the Service Line
Irrigation schedules reset after power outages, valves stick, and mainlines break under parking lots and landscaping. Check the controller and walk the zones. The underground service line from the meter to the building can also leak without surfacing in sandy soil, especially under pavement. Our guide to underground water line leak signs applies to commercial lines too.
Fire Lines
Fire sprinkler systems are usually on a separate service and meter. A leak in a fire line, which may be detected by a meter or by system pressure changes, needs a licensed fire protection contractor. See fire sprinkler line leak detection.
When to Call for Detection
If after-hours readings show water use and you can't find the source, the leak is likely hidden: under a slab, in a wall, or underground. Commercial leak detection uses pressure testing of isolated sections, acoustic and correlation equipment, thermal imaging and tracer gas to locate it while minimizing disruption to your operation. See commercial leak detection.
Frequently Asked Questions
How do I know if my business has a leak?
Read the meter after closing and before opening. Water use when the building is closed points to a leak or equipment running.
Can a single fixture really affect a business bill?
Yes. A continuously running flush valve or urinal can use a significant amount of water.
Can leak detection be scheduled after hours?
Many providers can work around business hours. Discuss timing when you call.
What about leaks under the parking lot?
Underground lines are traced and listened to from the surface, so only the leak point needs to be opened.
Do you handle fire sprinkler lines?
Fire lines need a licensed fire protection contractor. We can connect you with leak detection; fire system repairs follow their requirements.
