A drain cleaner may be used on a periodic basis to clean soil residues from residential and commercial waste drains. The drain cleaner may chemically self-foam to fill a waste drain with the foam. For example, the drain cleaner may be provided in two or more parts that are physically intermixed during use of the drain cleaner. One part may include hydrogen peroxide and water while another part may include a catalase, an amylase, a protease, and an enzyme stabilizer. The drain cleaner may also include a surfactant present in at least one of the first part and the second part. Additionally, in some examples, the drain cleaner includes a sanitizing agent present in either of the two parts or in yet a third physically separate part. During use, the different drain cleaner parts can be dispensed simultaneously into a drain to generate a cleaning and/or sanitizing foam in-situ.