A tablet for use in a drip tray including an excipient selected so that the tablet will not fully dissolve in water at ambient temperature for a period of at least one month, more preferably up to 12 months, a biocide, at least one enzyme, preferably a proteolytic or hydrolase enzyme, and enzyme preserving means, such as a boron compound for maintaining enzyme activity in a moist environment. The excipient may be for example poly vinyl alcohols, high molecular weight polyethylene glycols, high molecular weight polypropylene glycols, esters or partial esters of polyethylene glycols or of polypropylene glycols, and high molecular weight thermoplastic surfactants. The invention also relates to methods for inhibiting the growth of biofilm in an drip tray or the like, including the step of adding to the tray a tablet according to the invention.