An improved method and apparatus to prevent clogging of condensate drain lines with a biocide delivery system that prevents the growth of bioorganic growth in the liquid trap using time release biocide tablets or liquid biocide. When using solid biocide tablets erosion and dissolution of the tables is reduced. When using liquid biocides, combination of initial release followed by gradual release of residual liquid biocide in the drain water is attainable. Drain line are promoted from clogging while being installed anywhere on the drain line upstream of the liquid trap. The apparatus can also be incorporated with a liquid trap, allowing placement anywhere in the drain line.