'Water' is not a Spanish slang term. It's an English word. However, in Spanish, 'agua' is the equivalent word for 'water', but it is not a slang. It's a common term used to refer to the natural liquid that we drink and that falls from the sky as rain.
Examples
- Spanish: Necesito beber agua porque tengo sed.
- English: I need to drink water because I'm thirsty.