Enter the catchment data below in milliliters from your catchment readings. Typically this data would result in pouring your catchments into a graduated cylinder or directly reading a catchment calibrated in milliliters. Enter catchments in groups of four to properly calculate the Low Quarter. 4-24 catchments can be entered. Note: For Ag drip and micro sprinkler audits enter the spacing in square inches for the catchment area to correctly calculate the precipitation rate.