I live in Europe (Belgium), where tap water is generally safe for drinking, but may vary in hardness and taste. It's pretty hard and not so good in my area, so I've been using (Brita) water jugs for a while now. I find this unpractical as somehow the jug is always empty when you need it, and it does not seem very ecological as it requires changing the (plastic-cased) filter every month or so, and the jug itself is not really durable, so I'm now looking into alternatives that are at least equally effective but more sustainable, preferably in the form of a small filter with an extra tap for drinking water, or a filter that can be mounted to the tap directly (Brita sells that as well, with slightly longer lasting filters, but you still end up buying and throwing away a lot of plastics). Physical space is a constraint.
I did some research but I find it hard to find independent and scientifically reliable information on this topic: basically every producer seems to propose the "ideal" solution and claims that everything else is bad for you and/or the environment. Here's the little I learnt, divided by filtering purpose
- the most reliable approach seems to be based on ion-exchange, using salt whose Na+ replaces the Ca+ in the water. However this takes a lot of space which we don't have, the salt has to be replaced periodically, and I'm not sure of the impact of using that much salt on the environment; moreover, comments to this answer raise doubts on its impact on human health.
- an approach based on Zinc: supposedly you just cascade a small zinc-releasing pipe into your main pipe, and it softens your water during several years (I somehow find this one hard to believe)
For filtering potentially harmful residuals, aside from Brita(-like) solutions:
- I found one product combining ceramic, silver, active carbon, and a cellulose filter which claims to remove a lot of contaminants, which is reasonably small and requires changing the filter every 8k liters
- This product optionally includes a zeolite filter for removing "heavy metals", but these are reasonably scarce in our tap water, and the filter is based on Na+ ion exchange: in this case there's no salt to replace but the health concern remains. Moreover, zeolites contain aluminum (however this may simply not be an issue if it stays bound in the filter)
- Other alternatives on the market are based on "energisation" and "water memory", all of which sounds like new age mumbo jumbo to me (but thanks for proving me wrong)
I trust my provider to kill bacteria and co., so I'm not interested in sterilizing the water.