Peptic ulcers affect approximately 3 to 5 per cent of the Canadian population. Helicobacter pylori (H. pylori)—a bacterium that causes chronic inflammation of the inner lining of the stomach—plays a key role in the development of peptic ulcers, chronic gastritis and gastric cancer. As H. pylori has been detected in water, drinking water may play a direct role in transmission of the bacterium. To date, minimal research has been conducted regarding the potential association between H. pylori infection and detailed water system characteristics, such as water source, treatment, well depth and aquifer. Neil Bellack is now conducting the first population-based research project that will examine the association between H. pylori infection and exposures to different water system characteristics, as well as other factors that may affect transmission of H. pylori such as sewage disposal methods and land use. Results from this study will identify the role that water systems and water quality play in the transmission of H. pylori, and point to potential mechanisms for blocking transmission of the bacterium and preventing infection.