Systems for controlling the level of water with in reservoir, such as in a catch basin for an infinity pool. One embodiment of such a water level control system comprises a system housing having a removable front plate with front plate openings, and a water inlet into the housing. The system further comprises a removable mounting plate within the housing, with the mounting plate removable from the housing when the front plate is removed. A valve is included that is connected to the mounting plate, with water from the reservoir entering the housing through the front plate openings. The valve is operable to allow water to flow into the housing through the water inlet when water within the reservoir water falls below a desired level, and stopping the flow into the housing when the reservoir is at the desired level.