How long do we need to boil water?

about 4-5mins

事實上真係要睇你有幾多水喎？

depend on the voltage of the boiler....the quanlity(how much water there)...
Ig u are using a normal electric kettle(電水壺) ,usually between 3 to 6 mins)

It depends on how much liters water u are going to boil.
Normally when u see the bubles in the water bubling and also steams coming out, the water has been boiled.