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 allowing the plant to go through a wet & dry cycle.