Watertite Bio Wash is a ready‑to‑use fungicidal cleaner designed to treat walls and surfaces infected with algae, fungus and microbial growth before waterproofing or repainting. It works as a protective film cleaner, inhibiting regrowth of algae and fungi so that subsequent primers, waterproofing coats and paints can adhere better and last longer.

It is applied by brush or similar tool, allowed to act, and then the surface is left to dry before the next coat; typical coverage is about 110–140 sq.ft/kg, and it is available in 1 L and 5 L packs for site use. Within the Watertite system it is the first “surface hygiene” step, used before Crack Filler, WaterLoc, DampSeal Primer and DampLoc topcoat to ensure a clean, bio‑free substrate.