Although I am not on well water, I am amazed at the crud which my whole house string filter catches coming in. I have a very small micron (don't remember the size) on the cold water line going up to the kitchen. When I am the least bit concerned about water purity coming from the public water supply for mixing up my F24 fixer, I draw water from the cold-water kitchen faucet rather than from the faucet feeding my basement darkroom sink.
In ye oldene days it was often advised to use tap water boiled in a stainless steel container, then filtered and stored for use in mixing chemistry. In the past I have done that; but not here in this house and with this set up.
Of course, I break all the rules as explained to me by the experts because for many years I have been collecting and storing the AC run-off water during the hot, humid summers here abouts in the National Capital Area.
I am told that this water, despite my filtering it before use, contains alien spores, detritus, neuritus, and neuralgia and will grow untoward life forms in my basement and especially in the alkaline environment of my D23. The D23 (and DK-25R replenisher) have always seemed to last forever, so I guess they just do not know.
That being said, I have now taken to boiling said AC water in a stainless steel pot for about five minutes, rather than just heating it in the microwave, when mixing developer and replenisher as I have done hitherto receiving the expert advices.