When someone is thirsty and wants a drink of Sydney tap water. Commonly used in Sydney.
"Can I please have a Warragamba Slammer? I am quenched. "
“Want a beer?”
“No thanks, I'll stick to my Warrgamaba Slammer.”
“Is that a vodka soda?”
“No, that is a Warragamba Slammer.”
“Can I have a glass of water?”
“You mean a Warragamaba Slammer?”