A capacitive deionization (CapDI) system comprising: a CapDI module having a fluid inlet and a fluid outlet; a fluid reservoir including a conductivity sensor for determining the conductivity of the fluid configured to provide information regarding the remaining ionization in the fluid after passing through the CapD) module; and a control board comprising: a controller; a conductivity sensor interface coupled to the controller and providing communication between the controller and the conductivity sensor; a switching regulator coupled to the controller; a power MOSFET polarity circuit coupled to the switching regulator; and a module connector connectable to the CapDI module and coupled to the power MOSFET polarity circuit; wherein the power MOSFET polarity circuit is configured to provide bidirectional electrical power to the CapDI module via the module connector; the switching regulator provides electrical power to the power MOSFET polarity circuit; and the controller is configured to control the providing of electrical power from the switching regulator to the power MOSFET polarity circuit based on the communication between the controller and the conductivity sensor, wherein the controller is configured to increase the current applied to the CapDI module, if a measured conductivity is above a threshold by increasing an applied voltage from the controller to the switching regulator and the controller is configured to decrease the current applied to the CapDl module, if the measured conductivity is below the threshold, wherein the controller is configured to collect conductivity information over a length of time and to calculate an average of the measured conductivity before comparing the conductivity to the threshold; wherein the control board is not larger than 10.16 cm (4 inches) by 10.16 cm (4 inches) in dimension; wherein the CapDI System is configured to deionize fluid via the CapDl module and direct deionized fluid tc the fluid reservoir for future use, and further comprising: a first valve coupled between the fluid outlet and a use device; and a second valve coupled between the fluid outlet and a drain. a CapDI module having a fluid inlet and a fluid outlet; a fluid reservoir including a conductivity sensor for determining the conductivity of the fluid configured to provide information regarding the remaining ionization in the fluid after passing through the CapD) module; and a control board comprising: a controller; a conductivity sensor interface coupled to the controller and providing communication between the controller and the conductivity sensor; a switching regulator coupled to the controller; a power MOSFET polarity circuit coupled to the switching regulator; and a module connector connectable to the CapDI module and coupled to the power MOSFET polarity circuit; wherein the power MOSFET polarity circuit is configured to provide bidirectional electrical power to the CapDI module via the module connector; the switching regulator provides electrical power to the power MOSFET polarity circuit; and the controller is configured to control the providing of electrical power from the switching regulator to the power MOSFET polarity circuit based on the communication between the controller and the conductivity sensor, wherein the controller is configured to increase the current applied to the CapDI module, if a measured conductivity is above a threshold by increasing an applied voltage from the controller to the switching regulator and the controller is configured to decrease the current applied to the CapDl module, if the measured conductivity is below the threshold, wherein the controller is configured to collect conductivity information over a length of time and to calculate an average of the measured conductivity before comparing the conductivity to the threshold; wherein a controller; a conductivity sensor interface coupled to the controller and providing communication between the controller and the conductivity sensor; a switching regulator coupled to the controller; a power MOSFET polarity circuit coupled to the switching regulator; and a module connector connectable to the CapDI module and coupled to the power MOSFET polarity circuit; wherein the power MOSFET polarity circuit is configured to provide bidirectional electrical power to the CapDI module via the module connector; the switching regulator provides electrical power to the power MOSFET polarity circuit; and the controller is configured to control the providing of electrical power from the switching regulator to the power MOSFET polarity circuit based on the communication between the controller and the conductivity sensor, wherein the controller is configured to increase the current applied to the CapDI module, if a measured conductivity is above a threshold by increasing an applied voltage from the controller to the switching regulator and the controller is configured to decrease the current applied to the CapDl module, if the measured conductivity is below the threshold, wherein the controller is configured to collect conductivity information over a length of time and to calculate an average of the measured conductivity before comparing the conductivity to the threshold; wherein the control board is not larger than 10.16 cm (4 inches) by 10.16 cm (4 inches) in dimension; wherein the CapDI System is configured to deionize fluid via the CapDl module and direct deionized fluid tc the fluid reservoir for future use, and further comprising: a first valve coupled between the fluid outlet and a use device; and a second valve coupled between the fluid outlet and a drain.