A water treatment device for providing activated wash water to a washing machine, the treatment device comprising: an inlet for receiving pre-treated wash water from a water supply; an outlet for passing activated wash water out of the treatment device and toward a washing machine; a conduit extending between the inlet and outlet for passing water from the inlet to the outlet; a photocatalytic assembly including a reaction chamber, a lamp disposed within the reaction chamber for generating ultraviolet light when activated, the lamp having a length of 10.2 cm (4 inches) to 30.5 cm (12 inches), a diameter of 1.27 cm (1/2 inch), and a rating of 5 watts to 30 watts, and a catalyst cell disposed within the reaction chamber for generating one or more oxidizing agents upon exposure to ultraviolet light from the lamp, the catalyst cell having a surface area of at least 50 cm 2 (8 in 2), and wherein the lamp has a length that is 50% to 150% a length of the catalyst cell, wherein the photocatalytic assembly does not generate ozone when activated; a connecting duct extending from the reaction chamber to an injector, the injector being coupled to the conduit to introduce air from the reaction chamber comprising oxidizing agents generated in the reaction chamber into the conduit to be mixed with the wash water, the injector being configured to supply 0.5 ppm to 2 ppm of oxidizing agents to the wash water, measured as hydrogen peroxide, wherein the oxidizing agents omit ozone; a flow sensor coupled to the conduit for sensing flow of wash water through the conduit; and a controller communicatively coupled to the flow sensor and to the photocatalytic assembly, the controller comprising logic components that enable the controller to receive from the flow sensor a flow state signal indicating that measured flow through the conduit is above or below a predetermined threshold, and based on the received flow state signal, activate the lamp of the photocatalytic assembly when flow is determined to be above the threshold and deactivate the lamp of the photocatalytic assembly when flow is determined to be below the threshold. an inlet for receiving pre-treated wash water from a water supply; an outlet for passing activated wash water out of the treatment device and toward a washing machine; a conduit extending between the inlet and outlet for passing water from the inlet to the outlet; a photocatalytic assembly including a reaction chamber, a lamp disposed within the reaction chamber for generating ultraviolet light when activated, the lamp having a length of 10.2 cm (4 inches) to 30.5 cm (12 inches), a diameter of 1.27 cm (1/2 inch), and a rating of 5 watts to 30 watts, and a catalyst cell disposed within the reaction chamber for generating one or more oxidizing agents upon exposure to ultraviolet light from the lamp, the catalyst cell having a surface area of at least 50 cm 2 (8 in 2), and wherein the lamp has a length that is 50% to 150% a length of the catalyst cell, wherein the photocatalytic assembly does not generate ozone when activated; a reaction chamber, a lamp disposed within the reaction chamber for generating ultraviolet light when activated, the lamp having a length of 10.2 cm (4 inches) to 30.5 cm (12 inches), a diameter of 1.27 cm (1/2 inch), and a rating of 5 watts to 30 watts, and a catalyst cell disposed within the reaction chamber for generating one or more oxidizing agents upon exposure to ultraviolet light from the lamp, the catalyst cell having a surface area of at least 50 cm 2 (8 in 2), and wherein the lamp has a length that is 50% to 150% a length of the catalyst cell, wherein the photocatalytic assembly does not generate ozone when activated; a connecting duct extending from the reaction chamber to an injector, the injector being coupled to the conduit to introduce air from the reaction chamber comprising oxidizing agents generated in the reaction chamber into the conduit to be mixed with the wash water, the injector being configured to supply 0.5 ppm to 2 ppm of oxidizing agents to the wash water, measured as hydrogen peroxide, wherein the oxidizing agents omit ozone; a flow sensor coupled to the conduit for sensing flow of wash water through the conduit; and a controller communicatively coupled to the flow sensor and to the photocatalytic assembly, the controller comprising logic components that enable the controller to receive from the flow sensor a flow state signal indicating that measured flow through the conduit is above or below a predetermined threshold, and based on the received flow state signal, activate the lamp of the photocatalytic assembly when flow is determined to be above the threshold and deactivate the lamp of the photocatalytic assembly when flow is determined to be below the threshold. receive from the flow sensor a flow state signal indicating that measured flow through the conduit is above or below a predetermined threshold, and based on the received flow state signal, activate the lamp of the photocatalytic assembly when flow is determined to be above the threshold and deactivate the lamp of the photocatalytic assembly when flow is determined to be below the threshold.