Tap water tastes like soil

I've traveled a lot of Australia, and I have a small water filter that I take with me everywhere, because there are many many town's water that taste like earth, or dirt, or dusty.

Depends. How do you get your water??

Not in Australia, but: I have my own waterwell (just a 4 meter deep hole in the ground) and learned that water tastes different nearly each day. A little rain, no rain, heavy rain, long showers or short, the length of periods between the rain's ..... it all has an impact on the taste. For what I know, it's more constant if you get your water from greater depths. That's probably why a water company (who often use larger reservoirs on greater depths) have a more constant taste. that and usually a lot of water treatment.

Ph might be out of balance