I live in another part of the world (NE Florida) where - even with a water softener - everything that comes into contact with water develops a lot of mineral deposits. It is usually easier to replace less expensive products (whether they are coffee makers or faucets with lots of tiny holes) than to clean them (after a few years). Vinegar works in something like a coffee maker - up to a point (about 2-3 years). The trick with vinegar in a coffee maker is to flush it out with about 10 runs of clear water. You can use a wire brush on faucet filters (if the faucets have removable filters).

FWIW - I use a Bunn coffee maker - which has a mechanical cleaning tool. Works better than most chemical cleaning agents.

One product that works well (best I have found) in terms of things that are very expensive to replace - like the tile in your shower - is A-maz water stain remover. It is a paste with a mild abrasive (I'd test it first before using it on a high gloss surface). If you have a large mineral build-up - it may take 2-3 applications and a little "elbow grease") to get the tile clean - but it is worth it. A once a month or so application thereafter will keep things clean in the future. The product is sold here in glass stores. As for Argentina - I don't have a clue. Another handy item for cleaning things like toilets is a pumice stone. Our local hardware stores sell pumice stones on a stick - so you can keep your hands out of the toilet. They charge a premium for the "stone on a stick" - but it is worth it IMO. Robyn