Basin is being used to refer to the following things:
- A sink with a faucet, like post #6354662
- Various washbowls, like post #6228695, post #7808527, post #8246830
- A utility basin not for washing, like post #9697327 (Rating:S)
Since basin has so many definitions, I think in the first two cases, we should always tag them as sink and washbowl, and in the third case, maybe there are better ways to tag non-washing basins like heavy duty basins and medical basins.