The lowest flow rate that Flume can detect depends on the water meter. In general, smaller water meters can detect lower flow rates.
For instance, most homeowners have 5/8" or 3/4" water meters. On these meters, Flume can detect flow rates between 0.01 and 0.03 gallons per minute (GPM). That equates to roughly one gallon per hour (GPH). That is precise enough to catch even a drippy faucet.
On larger water meters, we can still detect very low flows. For instance, on 1" and 1 1/2" meters, Flume can detect flow rates between 0.02 and 0.07 gallons per minute (GPM). That is still low enough to catch even the smallest of leaks.