Do what water suppliers have ...

Do what water suppliers have always done. Anticipate the usual ups and downs of rainfall and have adequate storage capacity. If you are in an area of increasing population and strained access to natural water, build a wastewater recycling system so you will get multiple use of the water that you have and thus be more independent of the water source and become more sustainable. Of course, you might have to think about periodic water use restrictions, but keep in mind that drinking water represents less than 1% of the treated water that is delivered. Non potable uses far exceed the drinking water, so place restrictions on non potable uses. Also, Fix the leaks in your distribution system. Most systems have very high water losses because they do not provide adequate distribution system maintenance and replacement.