In many districts, growers now need to monitor their water use with a water meter. However, regardless of whether your water supply is abundant or low, it makes sense to only use the amount of water needed to actually grow a particular crop.
Some crops actually benefit from selective irrigation.
For example, apples can have better blush colour when there is an irrigation defecit. Reduced irrigation can also lessen stem-end splitting in apples. This article examines some of the ways in which you can irrigate your crops to allow for efficient water use without affecting the growth of the crop. In other words, supply sufficient irrigation water to the rootzone to compensate for what is being lost to the air by transpiration. However, instead of focussing on merely wetting the soil, we should irrigate to supply just sufficient water to active roots to meet the requirements of the plant.