Plants can't survive without water and if Mother Nature does not provide enough, you must make up the shortfall if your garden is to thrive. But it needn't take hours of your time.
First of all, prevent unnecessary water loss from soil and potting compost by applying a layer of mulch to damp soil in spring, and adding water-retaining gel to compost in pots and hanging baskets (or buy compost with the gel already in it). Topping up containers with decorative pebbles helps, too, as does choosing hanging baskets with a built-in water reservoir.
Water in the early morning or the evening, to give it time to soak well through. Use saucers on smaller patio pots. When it comes to borders, your established plants may only need an occasional thorough soak but any new plantings, especially annuals and vegetables, will need more help.
With a watering can or a hose (an extended lance nozzle is great for this), deliver a fair amount of water to the soil directly at the base of the plant. Set the nozzle to a low-pressure spray to reduce run-off. Any water put onto leaves will be wasted – remember your water meter!
A great way to target water to where it's most needed is to sink flower pots or upturned plastic bottles (the bottoms cut off) next to plants, and pour water into those.
Have you considered an automatic irrigation system to save both water and your time?
A lawn will survive a dry summer even if it turns brown but if you need to keep it green, only use the sprinkler on a calm evening. Longer grass deals better with drought, it shades the soil surface reducing evaporation. This works even better if you leave the clippings on. Make sure the blades are sharp and they cut cleanly rather that tearing the grass.