Drinking water buffer intensity simulator (BIS): Development and practical simulations

Abstract

An established body of research over many decades has identified the importance of both bulk-water and pipe scale surface microenvironment buffering to meet distribution system pH targets and reduce corrosivity toward metallic piping and components. Buffer intensity quantifies the ability of water to resist pH changes, and the greater the buffer intensity, the more resistant the water is to pH changes. To provide a practical tool for exploring buffer intensity, a buffer intensity simulator (BIS) was implemented in open-source R code, incorporating typical chemical species (e.g., carbonate and orthophosphate) that contribute to drinking water buffer intensity along with temperature and ionic strength impacts. The BIS was verified against a parallel spreadsheet implementation and is publicly available at https://github.com/USEPA/BIS. Simulations were conducted to illustrate impacts related to buffer intensity using three practical scenarios: carbonate buffering in drinking waters, temperature impacts, and free ammonia presence from chloramine use and/or source water presence.