How do you say: flush the toilet? in Spanish

I smiled to myself when I saw this posted in a bathroom. During my brief travels aboard "toilet" was an important topic to know how to say. If you recall, I stayed in a hostel that was big on conserving water. Beside anywhere you go  – Dónde es el baño? is one of the first questions that one should always ask.

So, as I looked as this sign - I thought to myself what is up with this translation? Why do people struggle with translating this topic? I wondered: Do people who are not hispanohablantes walk away saying: I know how to say “flush the toilet”? Are any hispanohablantes annoyed? What is Spanglish? Is it a means to an end? Can it be consider tolerance and appreciation for another's culture? It is grammatically correct. What academics opinons on this? I am pretty sure I took a class about jargon, dialects and  Ebonics in college - look out for more information to come. Or feel free to post  any links to related literature.

How do you say "flush the toilet" in Spanish?