Israel recycles 86% of water from the sewers compared to the second most efficient recovery in the world is Spain at 19%.
http://www.smartpeoplepodcast.com/2015/10/26/episode-214-set...
tldr; water was used as an excuse by the British to limit immigration to Israel, so from the earliest onset of the formation of Israel, Israel has been trying to tackle the problem of water use inefficiency.