Still or sparkling water?
friz-ZAN-te — three syllables, double 'z' pronounced 'ts', stress on the middle syllable.
This is the question the waiter will ask you. Knowing the answer — 'naturale' (still) or 'frizzante' (sparkling) — is essential.
In Italian restaurants, tap water ('acqua del rubinetto') is rarely served automatically. You will almost always be offered bottled water. 'Naturale' means still, 'frizzante' means sparkling, 'leggermente frizzante' means lightly sparkling.
Naturale, grazie.
Still, thank you.
The simplest answer — just the adjective
Frizzante, per favore.
Sparkling, please.
Direct and clear
Del rubinetto va benissimo, grazie.
Tap water is perfectly fine, thank you.
Acceptable in casual places — some may look surprised but will comply
Italians drink a lot of sparkling water — 'frizzante' or 'gassata'. In the south, still water ('naturale' or 'liscia') is more popular. Asking for tap water in a mid-range restaurant will not offend anyone, but you may get a surprised look in more formal establishments.