I used to give my dogs filtered tap water. It's what the whole family drinks in France where I live. The water quality is pretty good in the area (from spring water in the Pyrenees) so we have no complaints. In Malaysia where I grew up, I used to use filtered water as well but luckily I lived (at the time) in an area near huge limestone caves with good mineral deposits in the local water supply.
For my fish pond in Malaysia, I used to use tap water that I would turn on very low until it comes out in a trickle. When changing water, I would flush out about one quarter of the water level and then turn on the tap at a low trickle. The water would slowly trickle to fill up the pond and this helps to maintain the water temperature as too much tap water suddenly added into the pond will change the temperature and possibly give the fish a shock. This way, they have time to adapt to the new temperature.
