Most tap water contains a mix of pollutants. Even bottled and filtered waters contain impurities.
The only guaranteed way to get the absolute purest water is steam distillation using a water distiller. Distilled water is 99.9% pure water. By using a water distiller you get water that is purer than any bottled or tap water and purer than any other type of filtration or purification method.
With this water distiller the water is first gently boiled. This kills off viruses and bacteria and leaves most of the pollutants behind. The steam is then captured in a stainless steel coil where it cools to form pure water. This water then passes through an activated charcoal filter to finally remove any trace impurities.
Most bottled water is more expensive than petrol. Using a GT Sonic water distiller the cost of water works out at about 9p a litre over a typical year of use.
The water distiller produces 4 litres of absolutely pure water in five to six hours; fill it up, switch it on and let it run.