In Germany, the water is checked with special shrimp.  you have to imagine that.  These are really spoiled shrimp who only know hight quality water and if they only get a little trickier water they scream and freak out completely.  They are put in a container where the water just runs through.  there is a sensor that monitors the activity of the shrimp.  if the shrimp freaks out because the water does not meet its requirements, the sensor notices that and reports it.