The washbasin is designed for providing its user the opportunity to use the product as single basin and double basin at the same time. In single basin use, product provides a large shelf area; in double basin use, the shelf is cancelled and a new basins forms and this way the basin can be used by two people at the same time. By cancelling shelf aspect, the shelf which is not used anymore can be used as shelf in bathroom furniture with mounting elements provided when it is requested.