Originally Posted by rlitman
Could they be drain flies? I would run some hot water down each drain every night before you go to bed, and then pour in a shot of enzyme drain cleaner.
If they are fruit flies, you just need to clean up any food particles, but I don't know about fruit flies in a bathroom. Sounds kinda not right to me.
Because it is both the Kitchen and Bathroom at the same time Drain Flies sounds very likely. I like to use a Aerosol Spray can of Fly Spray. That way I can also hit the Overflow pipe located in the front of most bathroom sinks. I find that works the quickest. But certainly Boiling water or Bleach etc can also be used. The name of the game is understanding the problem and diagnose it.