Is it rude to refuse tea?
What it really means
Not rude, but the offer of tea is really an offer of welcome, so a flat "no" can land a little cold. Soften it: "I'm fine, thanks — maybe later" or accept something else: "Could I just have some water?" Accepting a drink, any drink, accepts the hospitality — that's the part that matters.
Context, tips & common mistakes
Refusing tea is allowed — the offer is a welcome ritual, not a test — but refuse it warmly and with a reason-shaped noise: 'I'm alright thanks, just had one' does perfectly. A bare 'no' lands colder than intended, because the question was really 'you are welcome here'; your answer should accept the welcome even while declining the drink. Accepting something (a glass of water) visibly relaxes hosts who need to provide.
Expect the second offer ('sure? Kettle's on anyway') — that is the go-on-then mechanism, not pressure — and know your second refusal will be final and respected. One institution worth knowing: offering tea to tradespeople working in your home ('tea or coffee? How do you take it?') is close to a national covenant, warmly received and quietly noted; a builder's verdict on a household often begins with whether the tea flowed.