In smallholder irrigation systems where farm sizes are below 10 hectares pose management problems especially where the availability of water for irrigation is frequently less than the demand. The number of system adjustments that meets each individual farmer’s demands, and the administrative complexity of measuring and accounting water deliveries have proven to be excessive when attempting to meet ‘on demand’ schedules, often resulting in chaos. An alternative operational design known as a ‘structured’ system which provides a simple service based on proportional sharing of available supplies on the basis of landholdings has proved to be more resilient. It provides a clearer definition of water entitlements and the responsibilities of agency staff and farmers. These systems are most suited in regions where water is scarce, clear definitions of water entitlements are lacking, management capacity and investment resources are limited. This report describes an appropriate approach to determine critical aspects of a structured system design.