The AQUAvalve 9mm is supplied with all AutoPot Watering Systems. Once connected to the water supply the AQUAvalve will control the flow of water to the plants, by simple gravity pressure from a tank or water butt, no pumps, mains water pressure, electricity or timers are required. Once connected to a tank the AQUAvalve will open and allow water to fill the tray to a preset level of 20mm. The AQUAvalve will not refill the tray until all the water has been used.