*Savings are based on comparing an unregulated flow rate (ltr/min) and usage in minutes, in a household of 4, versus a regulated flow rate (ltr/min) . For a wash basin these were: 4 minutes with an unregulated flow rate of 10ltr/min compared with an regulated flow rate of 4ltr/min. For a sink these were: 3 minutes with an unregulated flow rate of 12ltr/min compared with a regulated flow rate of 6ltr/min. For a shower these were: 8 minutes with an unregulated flow rate of 15ltr/min compared with a regulated flow rate of 8ltr/min. Water is at an average cost of £2.73 per 1000 ltr for the supply and gas £4.64 per 1kWh. These costs were accurate as of November 2013. A full and detailed account of how savings are calculated can be found on the www.wondervalve.com/water-calculator-explained