Safeguarding distribution system integrity

Keeping a residual is important, but it is only one of many actions needed to safeguard the integrity of the distribution system. When water utilities began using chlorine for primary disinfection, a residual in the distribution system came with it. Regulations have made the distribution system residual an increasingly important requirement in many parts of the world. However, many groundwater systems commonly operate without a residual, and several European utilities now operate with no residual in treated surface water. This article examines the reasons often cited for maintaining a disinfectant residual and discusses the merits of alternative residual disinfectants.