I have been trying to make coffee at work for a little while now.
Started with a plastic pourover. I used my fresh roasted beans, and a hand grinder, heated water in the microwave. Coffee had a funny aftertaste. I thought I might be overextracting, but I made sure I did not brew for longer then 4 minutes, and it still had the funny aftertaste.

Bought a brew and go, and same funny after taste.

Then, I read Jim's very long water paper, and wondered about the water.

Water at work was either bottled water, or filtered water. After reading the paper, I looked under the sink, filtering method is RO.

I decided to buy a box of baking soda, and see if that helps.

Bingo, a little pinch of baking soda in the water, and the funny aftertaste was gone.

I can now enjoy work coffee, because I can make it myself, and no funny aftertaste.

BTW, the normal work coffee is bad enough so I think it masks the aftertaste.

Who would have thought water is not all the same?

Randy