We're off to Finland for a week as DH's family are Finnish. We're in a summer house by the lake. My twins will love it but I'm concerned about the safety of the lake, not just the fact that we're by a huge expanse of water but also about the parasites and bacteria that can be caught from swimming in lakes. Does anyone have any good advice about this ? Does Coke kill tummy parasites? Should I go to the docs for advice..? Am I being just a little bit overprotective and should I just let them go wild and not worry about germs/parasites?