The most efficient way to water is using a drip system which is on a timer and which works at night, except in the winter. During the winter be sure to only water in the mornings. We all forget that the sprinkler is on, so either install a timer that will switch off the water, or set a timer on your phone or watch. A watering can is a sensible way to water newly planted seed or plants as you will then know exactly how much water you are giving the plants. Gardeners love to fleetingly water the top 2 cm of soil and this will evaporate very quickly. It's much better to do a long soaking where the water reaches beyond the roots and that is only necessary once a week. Please don't let your gardener turn the soil as that encourages the soil to dry out. Rather ask him to dig in lots of compost and cover the soil with a thick layer of mulch both of those will help to retain the moisture. Harvest the water from your roof and use the grey water from the kitchen and the bathroom. One of our customers told me that she showers with 4 empty buckets around her so that she doesn't waste any water! Practice recycling by using your fish tank water on your garden. Wash your fruit and vegetables in a bucket and save that water for your garden as well as the water in which you have boiled your vegetables. Keep the bucket handy to save all your water. As the saying goes,"every drop counts."