Glossary
Q1 (minimum flow rate)
The lowest flow rate at which a meter must give readings within the maximum permissible error, under ISO 4064 and OIML R 49. Below Q1 the meter may still register, but its accuracy is not specified.
Why it matters
Dripping taps, trickling cisterns and low-pressure supply all run at low flows. A lower Q1 means more of that water is measured within limits.
Source
ISO 4064-1:2014; OIML R 49-1:2013