Liquid level maintaining device

The present invention pertains to a plant watering system that is particularly suited for a plant container with a reservoir of water below the plant. The watering system uses a pilot controlled sequence valve to maintain the water level of the reservoir. The sequence valve includes a diaphragm that is pneumatically coupled to a pilot port fixed to the reservoir and submersed in the water. When the water level in the reservoir reaches a lower limit, the reduced pressure on a diaphragm causes it to open a pathway for water to flow from a water supply to the reservoir. When the water level reaches an upper limit, the increased pressure on the diaphragm causes it to close that pathway and shut off the water flow. The water supply can be an elevated tank or the pressurized water system. A pressure regulator can be used to lower the water pressure at the intake of the sequence valve. A nozzle controls the flow rate of water into the reservoir.