Farmers across the country will have to start installing water meters from next week, when new regulations on water measuring come into force.
From Wednesday, irrigators will have two years to install meters on all water extracted at a rate of more than 20 litres a second.
Water taken at a rate of more five litres a second will have to be metered within six years.
Irrigation New Zealand has been holding public information meetings about the new rules since October.
Its chief executive, Andrew Curtis, says putting in the meters will be a challenge for regions like Canterbury where there are a large number of water takes.
Mr Curtis says meters will have to be installed in Canterbury at a rate of about 160 a month.