By boiling, we mean heating the water to 100oC for two minutes. The water should bubble and most of the bacteria will be neutralised or killed. It is important to comply with the recommendations for temperature (boiling water should bubble) and time.
Water can be boiled effectively in an ordinary kettle or saucepan. If you are using a kettle, the water should be boiled twice with an interval of two to five minutes. Cool the water after it has boiled and pour it into bottles. Avoid using plastic bottles because they make the water taste of plastic.
Water in coffee or tea makers rarely reaches the required 100oC for two minutes. Therefore, these machines are unsuitable for boiling water.
Boiling water taps (e.g. Quooker) do not heat the water for long enough to kill the bacteria. Therefore, water from these taps should also be boiled as mentioned above.