Remote flush

Penny-pinching water companies will love William Paterson’s cunning plan for
saving water: he plans to use radio to control the amount of water used to flush
a toilet (GB 2 315 500). All new cisterns, he suggests, will be divided into two
chambers, one large and one small, connected by a valve. When the valve is open,
the whole cistern fills. When the valve is closed, only the small chamber fills.
During water shortages, a water company can transmit a coded radio signal that
makes a receiver in the cistern close the valve. That way everyone in the area
uses half as much water to flush. The plan effectively automates the practice of
placing a brick in the cistern to cut the flushing volume.