Safety and sustainability of potable tap water irrigation in endoscopy in Canada: an interrupted time series study

Summary: Background: International guidelines recommend sterile water for endoscopic irrigation despite limited evidence. Single-use plastic sterile water bottles generate substantial costs, greenhouse gas emissions, and microplastics. We sought to estimate whether replacing sterile water with potable tap water for endoscopic irrigation affected clinical outcomes.

Methods

This quasi-experimental study involved an interrupted time series design at a multi-campus tertiary care academic health system (The Ottawa Hospital, Canada). All adults undergoing esophagogastroduodenoscopy, colonoscopy, flexible sigmoidoscopy, enteroscopy, ileoscopy, or pouchoscopy between February 2024 and August 2025 were included. A system-wide switch to tap water took place on February 10, 2025. The primary outcome was a composite of emergency department visits, unplanned admissions, or deaths within 7 days post-procedure. Infectious complications within 30 days constituted secondary endpoints. Data were obtained from validated institutional databases. Segmented regression modeled the weekly outcome proportion to estimate the step change post-implementation, with a non-inferiority margin of <0.5% absolute risk increase.