Whenever the PUB provides figures related to water production or consumption, it always uses gallons, such as in “400 million gallons per day” of daily water demand.

Why does the PUB still use gallons instead of expressing in litres (or kilolitres) for the measurement of water, such as when its Chief Executive Officer talked about water usage during an event commemorating World Water Day? (“Daily water usage exceeds level during haze last year”; March 14).

As a government agency, it should use metric units; instead, it uses units that many of us may not understand.

The PUB also did not state whether the gallons were imperial gallons or United States gallons — for those who use imperial gallons, the unit is equivalent to 4.54 litres. In US gallons, it is equivalent to only 3.78 litres.

As far as I know, not many of the younger generation know how much one gallon of water is or its equivalent in litres.

Singapore has stopped using imperial units and has adopted the metric system for all measurements and weights since the 1970s.

For the pioneer generation, we are familiar with the one-gallon and five-gallon metal containers that we used to have at home to keep water and other food items. My grandson, who learns only the metric units in school and daily life, is confused about gallons.

I hope the PUB can adopt the metric system as it seeks to keep us informed about water usage.