I am by no means sure that there is a definitive, simple answer. Such impressions are largely dependent on the nerve endings and molecular sensors in your taste buds. However, they also depend on the way your brain interprets messages from your taste buds. Such things differ between people, which reduces most explanations to hand-waving. Now, chlorinated water kills germs by being powerfully oxidising, and that same quality can make it affect or damage the receptive surfaces of your taste buds. This can affect the selection of taste molecules that can dock in the receptor molecules, and possibly the mode in which they dock and stimulate the nerve endings. Once you stop drinking such water, the taste buds would recover in a few days or so, as your taste buds replace their sensory surfaces, and once again you could find that normal "earthy" water tastes as it did before you did you taste buds violence. You could try obtaining a filter such as some of the better charcoal types (I could recommend a brand that we have used for years, but I hesitate to get all commercial here). I strongly approve of chlorination, but I don't much like the taste. My prediction is that if you drink such filtered water, the effect will vanish. By way of analogy, I regularly use a chlorhexidine-based mouthwash (home-made, but one can buy such.) It works dental and anti-ulcer marvels, but is astringent and also affects my taste buds, no doubt by masking some of the molecular docking sites. The upshot is that I soon no longer notice the effect unless I stop using it, which I seldom do. Apparently people who stop smoking also find that their sense of taste changes, and no doubt for similar reasons.