What could we possibly find in it?

Small traces of chemicals, microorganisms and bacteria may occasionally be present in water before treatment. Any pesticides found will be at extremely low levels which are not harmful to health. Nitrates from fertilizers may also be found in pre-treated water which could be harmful to very young babies. Lead could be found in drinking water, coming from the lead pipes in your house, and is suspected of affecting the mental behaviour of children. Iron occurs naturally in many water sources but can also be added to water by the corrosion of water mains, although is unlikely to be harmful to health.