Toads return to the water to breed (where they lay spawn which hatches into tadpoles, just like frogs) and at other times will spend brief periods there. When not breeding they like a moist environment and will try and situate themselves where they can find worms, slugs and other insects which are their main diet. If you can put some shallow containers of water around your garden they will appreciate it, especially in this hot weather, or water spray some of the undergrowth to provide a damp place. This will encourage worms or slugs for them to eat.