About 15 years ago, I played with a modification to an irrigation system, that seemed to work quite well. We had a large lgarden that required a pop up system for the summer months and also required a drainage system for periods of heavy rainfall.
The solution we came up with was to design the irrigation so as to be installed with a drainage system, allowing the drained water via stone filters to be temporarily stored in an underground tank. This tank stored the water until the irrigation tank required water, the water was then pumped into the irrigation tank for reuse, before topping up with water from the house supply.
This system worked well on two sites... since then I have spent a number of years in the USA where temperatures are much higher and much lower - 120f in the summer and -28f in the winter. with an annual rainfall of 38 inches (900mm).
Today I have been working with a system that reduces watering needs by up to 80%
The first part collects water from hard surfaces and then stores in a drainage system, before being recycled back to the lawn and shrub areas via a dripline irrigation system - driplines reduce watering needs of plants significantly.
The final piece of the jig saw is almost ready - a way to store some of the much needed, but available rainwater in the soil for use by lawns and shrubs - it would seem that this part of the system is able to reduce watering by a factor of 50% whilst it also feeds and aerates the soil at the same time.