There was a bit on the old Mary Tyler Moore show which got laughs - Mary wondered if you need to wash a pot if all you did was boil water in it, the answer being of course not.
Not knowing where you live or whether your water supply is unreliable or you are just worried about it, it’s impossible to pinpoint the problem. If you have very hard water, a chalky residue of minerals would eventually build up in the pan but in general, with a stainless steel pan, I doubt that the pan is the issue. If you take any daily medications orally, that might be it. Many of them affect the taste buds. Or, maybe what you are tasting is the dish soap. You shouldn’t need to be cleaning the pot at all.
If you have a microwave, try boiling water in a glass cup/bowl. If that also tastes odd to you, the stainless pan is not the problem.
As to naf’s suggestion, it would be baking soda, not powder.