Abstract: A foam generator is provided for generating a treatment foam within a pipe, such as a sewer pipe, in need of treatment. The foam generator includes a foam generating head having a first perforated conduit for carrying a fluid such as compressed air and a second perforated conduit surrounding said first conduit for carrying a fluid such as a liquid which contains a foaming agent and a treatment chemical. A wicking material surrounds the first and second conduits in the foam generating head and receives the compressed air and liquid from the conduits and causes the production of a foam. A pressure casing can surround the foam generating head for delivering the foam under increased pressure to coat an inner wall surface of the pipe.