Hello Bernhard,
Gomphonema acuminatum for the first
Diploneis Eliptica for the second
Synedra (ulna ?) with Meridion circulare for the third
These diatoms can be found only in freshwater with minor pollution
The maximum probability to find them is in P6/P7 class wich seems that the water is very clean... you are lucky, you can drink it...
best regards
Dominique