A section 104 agreement, often abbreviated s.104, is a formal agreement under the Water Industry Act 1991 by which a developer commits to build new sewers to adoption standards in exchange for the sewerage undertaker, such as Thames Water in Greater London, taking on long-term maintenance once construction is complete. The agreement covers design approval, materials, testing, inspection and a bond against defects. Practical implications for residential developers across London include the need to follow Sewers for Adoption design code requirements, including BS EN 752 and Thames Water specific supplements. Once vested, the adopted sewer becomes a public sewer maintained at the water company's cost. Homeowners purchasing new build property should ensure that the section 104 process is complete or expected to complete promptly, as unadopted sewers remain a private liability.
Section 104 agreement (s.104)
Agreement under the Water Industry Act 1991 for new sewers to be adopted by the water company.
