If you’ve started exploring sewer credits for your cooling tower, you’ve probably encountered the term “makeup water meter” \u2014 and you may be wondering what exactly it measures and where it goes. This small piece of equipment is the cornerstone of your sewer credit documentation, and understanding it helps you make smarter decisions about installation and monitoring.<\/p>\n
Makeup water is simply the fresh water that enters your cooling tower to replace the water lost to evaporation, blowdown, and drift. Every gallon that leaves the tower through these three mechanisms must be replaced to maintain proper water levels. The city water supply provides this replacement water through a dedicated pipe called the makeup water line, and the meter installed on this line measures the total volume of fresh water your tower consumes.<\/p>\n
Think of it like a bathtub with a slow drain. The water level drops continuously, and a float valve opens to add fresh water. The makeup water meter measures how much fresh water flows through that valve over time. The U.S. Department of Energy<\/a> identifies makeup water metering as a fundamental requirement for effective cooling tower water management.<\/p>\n The makeup water meter is installed on the pipe that feeds fresh city water to your cooling tower, typically in the mechanical room near the tower or in the pipe chase where the water line branches off from the building’s main supply. The ideal location is as close to the tower as practical, but far enough upstream to provide the straight pipe runs that most meters need for accurate readings \u2014 usually five to ten pipe diameters of straight pipe upstream and two to three diameters downstream.<\/p>\n For most commercial cooling towers, the makeup water line is 1.5 to 4 inches in diameter. The meter must match this pipe size. If your tower has multiple makeup connections (some large installations do), you’ll need a meter on each one to capture total makeup flow.<\/p>\n Installation typically requires a licensed plumber and takes a few hours to a full day, depending on accessibility and whether the building water system needs to be shut down during the work. If a system shutdown is unacceptable, an ultrasonic clamp-on meter<\/a> can be installed without cutting into the pipe \u2014 though insertion and inline meters generally provide better long-term accuracy.<\/p>\n The makeup water meter provides the primary data point for your sewer credit application<\/a>. When you tell the utility “my cooling tower evaporates X gallons per month,” the metering data is your proof. Specifically, the calculation works like this: evaporation equals makeup water minus blowdown minus drift. If you also meter the blowdown line, you can calculate evaporation precisely. If you only meter makeup, you can estimate evaporation using your known cycles of concentration<\/a> \u2014 but having both meters gives you the strongest case.<\/p>\n Utilities want to see consistent, documented data \u2014 not back-of-napkin estimates. A properly installed makeup water meter with 60 to 90 days of baseline readings gives your application the credibility it needs for approval. The EPA’s WaterSense program<\/a> recommends submetering all major water end-uses in commercial buildings as a standard practice for both conservation and billing accuracy.<\/p>\n Three meter technologies are commonly used for cooling tower makeup lines. Mechanical turbine meters are the most affordable and work well for steady flow rates \u2014 they’re accurate and reliable but have moving parts that eventually wear. Electromagnetic (mag) meters have no moving parts and handle varying flow rates better, making them ideal for towers with fluctuating loads. Ultrasonic meters clamp onto the outside of the pipe and require no pipe cutting, but they’re more expensive and can be sensitive to pipe condition and flow profile.<\/p>\n For sewer credit purposes, any properly installed and maintained meter type is acceptable. Choose based on your budget, your pipe conditions, and whether a system shutdown is practical during installation.<\/p>\n RPM Water Equity Solutions helps commercial facilities recover money lost to sewer billing assumptions. If your building has cooling towers, you may be paying sewer charges on water that never reaches the sewer system.<\/p>\nWhere It’s Installed<\/h2>\n
Why It Matters for Sewer Credits<\/h2>\n
Meter Types for Makeup Water<\/h2>\n
Ready to Find Out What You Could Save?<\/h3>\n