Hello!  

The first challenge is to confirm whether they are fruit flies or a drain fly.  They look very similar.  One way you can test is to take a clear glass that can fit over your kitchen drain.  Line it with some vaseline or other stickier substance.  If drain flies are flying out of the drain, they will come up into the glass, seeing light, but become trapped in the sticky lining and would confirm they are coming from the drain.

If fruit flies, you need to check around the pantries and kitchen for any overly ripe fruit or vegetable, potato, rotting onions that may have fallen behind a cabinet etc.  Clean up materials like that and put any food worth keeping into the fridge to slow or stop any fly development that may be within fruit.  If all fruit is cleaned up and out of the home, then we look more to the drains.  Often you can create little pan traps with apple cider vinegar or wine in a bowl with a drop of soap in it. it will attract the flies to the scent and the soap will break the surface tension of the liquid and they will drown in the bowl.  But you have to remove the breeding areas to eliminate the problem.

There are several species of drain flies that live on the gunky build up in drains and disposals, or burst sewage pipes or other organic matter in drain issues.  Cleaning those drains is challenging but goes a long way to preventing flies reproducing in the drain.  Different enzyme-based cleaners can help break down that gunk.  Also make sure your P-trap/U-bend of your sink drain is holding water which prevents sewage smells and drain flies from flying up from lower in the drain line.  Sometimes in sinks that don't get used frequently, those traps can dry out and allow smells or drain flies to move freely.  The pan traps can also attract some of these flies to reduce numbers flying around. 

Feel free to call the Extension Office of Medina at<personal data hidden> for more information or if you have further questions.