The audit starts with what actually comes out of the drippers, measured with a bucket and a stopwatch at eight points of the network, because a catalogue's nominal flow and the flow of a six-year-old line are not the same number.

A water balance per plot follows: crop needs, rainfall, soil water reserve. The deliverable is a rationing calendar, month by month, in cubic metres and pumping hours.

The report also names what is not worth the investment. An audit that recommends everything it saw is not an audit.