You probably don't want to know how we filter our water then [1]: "Slow sand filters work through the formation of a gelatinous layer (or biofilm) called the h

You probably don't want to know how we filter our water then [1]: "Slow sand filters work through the formation of a gelatinous layer (or biofilm) called the hypogeal layer or Schmutzdecke in the top few millimetres of the fine sand layer." Treating all bacteria as the enemy is really solving the wrong problem — the question is not how to kill all the bacteria (which is impossible, from almost thermodynamic considerations (if there is free energy and the ability for life colonize it, then there will be life)), but how to manage the bacteria so we favor nonpathogenic or useful species and help them outcompete the 'bad' bacteria. Incidentally, this is the same strategy our own bodies use—the immune system spends enormous amounts of effort discriminating between commensal/mutual and pathogenic species, and favoring the former as much trying to outright kill the latter. We need to pick the right analogies. How to herd, tame, and recruit allies, not just how to fight and kill. [1] https://en.wikipedia.org/wiki/Slow_sand_filter#Method_of_operation https://en.wikipedia.org/wiki/Slow_sand_filter#Method_of_ope...