The same applies to any other minerals or organics the supplied water may have contained. Let’s take lead: the water supplied in the Illawarra region as mentioned above, had a lead concentration of less than 0.0001mg per litre. To reach an unsafe lead concentration (0.01mg per litre, according to Australian guidelines) in a cup of water, you’d need to boil down roughly 20 litres of tap water to just that cup of 200ml.