City stairstep constant pressure water supply equipment and method

This invention discloses a kind of city cascade constant pressure supplying of water equipment and method. It includes water supply installation, water supply pipe network and constant and pressure device. The water supply device consists of a group of different frequency pump flow (5), its characteristic lies: there is pressure transducer in frequency pumps (5) one-way outlet valve (8) of water pipe, and it connects to the transducer (4) through lines, the transducer connects to controlled switches (6) through cable converter (3) frequency pumps (5) via wire connects to controlled switches, there are additional pressure and constant devices in the water pipes household heights tower. This invention has changed the traditional supply model, and achieved energy, saved money and prevented secondary water pollution.