According to one aspect of the present disclosure, a drain system, including a sensor in communication with a reservoir and controller, uses algorithmic control of a drain valve to adjust the interval and duration of actuation of the drain valve to regulate a fluid level within the reservoir. In embodiments applying the drain system to a gas compressor system, the disclosed control algorithm enables the controller to prevent the loss of compressed gas through an open path out the drain and further to prevent condensate generated by operation of the compressor system from backing up in the reservoir and reentering the flow of compressed gas. The control algorithm adjusts the interval and period of actuation of the drain valve such that as operating conditions change the drain valve opens more or less frequently for longer or shorter periods in response to varying condensate load.