Water filtration

Hi all,

I'm  wondering if anyone can give me some advice about filtering our water.

We have a concrete water tank and have spring water delivered by tanker.  We have a reverse osmosis system under our sink,  for drinking but it wastes such a lot of water. Showering and other water usage does not go through this process.    Does anyone know of a better system to use to make our water safe for all use, including drinking.

Thanks for any info, which will be much appreciated.