Is "You should drink more water" correct?

Why

Maanasi has correctly noticed that both sentences point in the same general direction — both are recommending drinking more water, so it's easy to see them as basically the same advice worded differently. Modal verbs like "must" and "should" actually carry different STRENGTHS of obligation, though, even when the topic is identical. "Must" signals something close to a strong requirement or near-necessity — a doctor telling a dehydrated patient "you must drink more water" means it urgently, almost as an order. "Should" signals gentler advice or a recommendation, something wise to do but with more room to skip — a friend casually saying "you should drink more water" is offering a helpful suggestion, not an urgent command. Test: notice you'd say "You must wear a seatbelt, it's the law" (a strong, non-negotiable requirement) but "You should wear comfortable shoes for the trek" (helpful advice, not a legal rule) — swapping the two words in each sentence would noticeably change how forceful each one sounds. No, "must" is stronger: it signals a firm requirement, while "should" offers gentler advice, even when both point toward the same action.