An antimicrobial coating slurry includes about 15.5 wt % of a wetting agent, about 6.0 wt % of an insolubilizer, about 1.1 wt % of a biocide agent, and about 7.8 wt % of an inorganic material that includes lithium oxide and the balance water. The slurry is applied to a heat exchanger surface, cured, and washed to form a hydrophilic coating that includes lithium silicate. The hydrophilic coating provides improved moisture wicking and a reduced dissolution rate of biocide, which is held within a lithium silicate matrix.