When there is prolonged dry weather any water you might add to your garden often either runs off at surface level or just does not soak into the soil. This is due to the surface tension of the water and a lack of organic ingredients in the soil (called hydrophobic soil).
The quickest way to help your plants AND SAVE WATER is to use a soil wetter or Wetting Agent. This breaks down the surface tension of the water and allows it to soak into the soil and get to the roots - which of course is your main objective. Most importantly, the water you do add to your garden is more effective - and as a result you'll definitely use less.
There are a few different types of soil wetters on the market - some are a thick liquid - a bit like washingup liquid - and you can also get it in hose on bottles and as granules to sprinkle over the soil and water in.
You can also consider making a mulch cover of straw and if possible digging it in a bit too - adding compost or composted manures at this point will also be good. Water then remains in the hollow parts of the straw and the other organic materials will absorb moisture as well.
And as for Jake's point about helping break down the soil hydrophobia you can try Water Storage Crystals from Yates - we sell it here in the Garden Shop, here's the link:-
https://www.gardensonline.com.au/Shopping/GardenShop/Show_6554.aspx