This usually means hard water, which is calcium and magnesium carried in solution.

Those minerals drop out of solution on anything hot and stay behind when a droplet dries, and they bind to soap instead of letting it foam.

Look for crust on the kettle element and the shower head, a chalky ring at the water line in the toilet, and more soap used for less lather.

Do not buy a cartridge filter for this. Sediment and carbon cartridges do not take hardness out, and any softener sized before someone has a hardness number is a guess.