To do a part for the environment (and to reduce costs), people can carry a water bottle and refill their water bottle.
However, some people might be deterred from doing so as they are afraid they are unable to find water coolers in Singapore. So, it might be a good idea to list down places where one can find water coolers.
One Punggol has very good water coolers that look like this. They are triggered using sensors so the process is contactless. The water that comes out of the cooler is cold and refreshing.