I washed my face at the washbasin.
We will install a new bathroom sink.
When I get up in the morning, I first wash my face at the washbasin.
He was standing at the washbasin brushing his teeth.
I cleaned the washbasin over the weekend.
シンク usually refers to a kitchen (or utility) sink, while 洗面台 specifically means the bathroom washbasin used for washing your face and hands.