Filtering or even buying water in fear of unclean tap water is no rarity in Germany even though the quality is good.
But our tap water is monitored more than the mineral water we buy. Our knowledge about the so called bad microbes is bigger then what we know about the harmless good ones. One glass of clean drinking water contains ten million bacteria, which actually help to purify the water. Sphingomonas are able to remove pollutants, other ones release substances that make the water taste and smell good.
The project ten million gives you a feeling of our vital water in a sensual way. What we cannot see, becomes haptic. We should appreciate the thousand different species, that make our water what it is: water of good quality.