I guess you get what you pay for. My eSpring cost me B30k, + 9 filters over 10 yrs approx B40k, gives me 5000ltrs per year (50,000 ltrs) works out at B1.4 per ltr. It is not a reverse osmosis unit so essential minerals remain but nano mesh & carbon + silver + uv light = good quality water for cooking, washing veg, tea/coffee, etc just by turning on the tap. I have been using it for more than 10 years!
not only is it cheaper in the long run but you dont have to carry water, just turn on the tap and move a small lever for filtered water. You then have water for cooking including tea & coffee, taste much better. Filling stations are not trust worthy - how clean are the filters, how often maintained etc.