A toilet with a small sink built into the top or lid of the cistern (aka the toilet tank). These sinks operate by drawing some of the clean water going into the cistern and diverting it to the faucet so people can wash their hands. The used water then enters the cistern from the sink. These sinks are directly tied to the toilet's flushing mechanism, so automatically run after flushing and shut off when the cistern is filled.
