Water, water, everywhere, nor a drop to drink.

[SandwichShortOfAPicnic]

Yes, but the tanks are designed to keep it sterile and safe. They're not cheap. It's very much an Australian thing (though we used to collect a lot of water in the UK for the garden in 5 × 1000L white plastic tanks in that metal cage (can't think what they are called right now (update IBCs)). It always looked good enough to drink but we never needed to test it. ).

Here in Australia it is very common to be on "tank water" if you're not in a town or city. And in cities and towns you'll still have tanks for collecting rain water for the garden or fire brigade use (Rural Fire Service volunteers). A lot of places will also have bore water which will have a separate pipe work for garden and toilet use. No point in flushing the toilet with your drinking water if you don't need to. In our last rental, the washing machine was also on the bore water with a decent filter in place before it. Living at the top of a mountain this time around we don't have that option, so the backup are 7 dams (it's a sheep farm, so there is serious contamination issues to consider before drinking it and during the drought the dams actually ran dry before we ran out of tank water (we actually didn't run out of tank water, but all you can do at that point is buy it in at $$$$ as our neighbour had to. )

There are quite a few countries I've drunk stream/ river and lake water in, but they are known for good quality water and little to no air pollution. The south of England isn't one of them, but when we lived in the lake district or water supply was from the beck at the back of the farmhouse. That went through a sand trap before getting to us. That was beautifully clean and clear. When I was living in the Scottish highlands, the water was stained brown with peat, but perfectly good to drink.
We see a similar colour residue build up in the kettle here at this place. It's from the gum leaves in the gutters of the shearing shed. They release a pigmentation that permanently stains clothes/ wool etc (and is used to dye fabric) when they soak in water.

I don't think I'd get over my fear something died in the water upstream
I had a fearful set of lectures on waterborne pathogens whilst young and impressionable, not sure I'll ever get past that.

Waterborne diseases are the number one killer in the world. Of course this figure is completely skewed by stats from developing countries with poor water supply but study it for a while and the idea of drinking untreated water, even well stored using well proven methods makes me shudder just a bit.

 

[badjak]

I was born and raised in the Netherlands and the water there is absolutely fine to drink.
Here (Zambia) I use Zambezi river water. It's safe to drink, although I generally boil it or use in tea or coffee.
No mining/major agriculture on this river.
If I go elsewhere, I use bottled water for drinking

 

[blades]

I couldn't fathom why everyone in Spain (well not quite everyone but a the vast majority) drink bottled water. The water here is classed as potable quality. When I tried to make a cup of tea with it and it was truly awful. It has almost a slimy quality and certainly makes odd tasting tea. I immediately bought a water filter and that made a little difference but not a lot.
So I look it up and apparently Spaniards buy water because in most areas they don't like the way their water tastes.

I've just tested the waters TDS (total dissolved solids) and it's currently at 376ppm so it's not a surprise the water has a 'flavour'
A brand new Brita filter doesn't even half it, it brought it down to 273ppm and theres still quite a film on the tea.
I don't want to buy bottled water, environmentally it bothers me and I'm not entirely convinced health wise drinking water stored in plastic bottles is good for you. So I'm thinking an upgrade to a Zero water filter might do even if they are rather pricey.

Can you drink straight from your tap or do you have to do something to make your water palatable?

I live in the country so we have a well for our water. It is rich in iron oxide but otherwise not bad. I use a Brita to remove the rust and then put the filtered water into a Zero Water to complete the drinking water filtration. The result is just like bottled water. You are on the right track I would say.