If you're watering them during the day the water droplets act like magnifying glasses and promote scorching. Also daily watering could be causing root rot.

I suspect you might be more likely to get a good answer at !gardeningaustralia@aussie.zone

Are these in ground plants or in pots? What type of plants? Is it all the plants or just ones in a certain area? Do you use mulch? What type of dirt do you have i e. Is it sandy or do you add compost etc? All these things can influence nutrient uptake, so let is know what you have and maybe some pics of leaves and we can help a little more

Be certain your tap water isn't softened. Softened water contain an elevated amount of salt that is harmful to plants.