Flow Meters: Part of a Resilient Response to Colorado’s Drought

The drought we face following the winter of 2026 is unlike anything Colorado has seen before. Our snowpack is at an all-time low, reservoirs are at 79% of capacity (compared to the 85% average), and there is less snow to melt and refill in the coming months.  As of April, 2026, the US Drought Monitor reports that 97 percent of Colorado is in Moderate to Exceptional Drought, due in part to record March warmth that depleted the already historically low snowpack.

In spite of these worsening conditions, we’re still not doing enough to conserve our most vital resource. In addition to using a lot of water in the normal course of our lives, we are also wasting a great deal. Sprinklers are a prime culprit. According to the EPA's WaterSense program, residential irrigation in the U.S. accounts for almost 9 billion gallons of water per day, or about a third of all household water use. Up to 50% of that irrigation water is wasted through inefficient systems, leaks, evaporation, wind, or runoff. Even small leaks can result in thousands of gallons of wasted water, because it’s not uncommon for irrigation problems to go undetected for a long time. Most systems run at night (to avoid excessive evaporation) when no one is around to notice leaks, and some leaks occur underground, where they are hard to see.

One solution combines a smart irrigation controller, such as those made by Rachio and others, with a flow meter. The flow meter is typically installed in the mainline of a sprinkler system, and it continually sends flow rate information to the controller. During an initial calibration step, the controller learns the average flow rate for each zone. Then, in normal operation, any flow outside a range selected by the user can trigger an alert on the user’s phone app or email. This could be the sign of a malfunctioning sprinkler head or valve. Any flow detected when the system should be off is interpreted as a leak, such as from a broken underground pipe.

There are several different kinds of flow meters, using different technologies to measure the flow. The cheapest is a sensor that has a rotating component like a propeller, paddle wheel, or turbine. Because these meters have bearings and rotating parts, they have shorter lifetimes and are less accurate than other technologies. At the high end there are electromagnetic and ultrasonic flow sensors that measure flow without having anything inside the pipe to restrict the flow. These are accurate but expensive.

Vortex flow meters occupy a middle ground. They are relatively inexpensive, but also very reliable due to the lack of rotating parts. A small bar placed in the flow produces eddies, or vortices, behind it. A piezoelectric sensor responds to these vortices, and electronics converts their frequency into a flow rate. There is a precise relationship between the frequency of these vortices and the flow rate, which makes this technology quite accurate.