My sister's toilet with a built in hand basin - it uses the waste water to fill the cistern for the next flush : r/mildlyinteresting
The Combi is an innovative modular unit that comprises of a WC with an integrated hand basi… | Small bathroom with shower, Small bathroom sinks, Small toilet design
SinkPositive Touch-Free Water/Space Saving Adjustable Toilet Tank Retrofit Sink/Faucet Basin White HD214-01 - The Home Depot
Close Coupled Toilet with Sink on Top - Legend - Better Bathrooms