IEA Radon_Reporter_April 2025

24 | APRIL 2025 UPDATE: Radon in Water Standards Detailed methods to collect a representative water sample for dissolved radon in groundwater were developed into the ANSI-AARST standard (MW-RN 2020). Edits to update and resolve public and committee member comments are underway. However, no standard exists for the installation, operation, and maintenance of a water mitigation system for radon reduction, and developing one has become the primary goal of the Radon in Water Standards Committee in 2025. Generally, when radon mitigation of a home water supply is desired, use of an activated carbon (AC) filtration system is applicable for lower concentrations, while aeration mitigation systems are applicable for any radon level. To date, the Committee has worked on drafting text regarding: • Chemical and other substances in water and how some interact with each other to impact potable water quality, system operation and occupant safety. • A Health and Safety section, largely similar to that currently in the standard on mitigation of radon in air (SGM- SF-2023), with attention paid to installation of another potentially back-drafting utility. • Plumbing requirements, such as by-pass valves to isolate individual components for exchange or cleaning, also support Operation, Maintenance and Monitoring (OM&M) goals. • Aeration system exhaust configurations to include: 1. Requiring a separate dedicated exhaust. 2. Methods (parts) to exclude entrance of external contaminants from entering the system through the exhaust port when not operating may have to be developed, and tested again freeze-up. 3. A timer to complete aeration of reservoir water below 5000 pCi/L • Activated carbon filtration systems discussion have included: 1. The suggested maximum radon in water to be treated by AC 2. Concern related to the practice of leaving “used” activated carbon for the homeowner to discard, since the contained activity can be significant (and detected by landfill monitors). • Other emerging methods have to be addressed. We thank the many highly experienced members of this committee in guiding the technical aspects of radon in water mitigation based on what is known and what we mutually learn during the consensus process. PROFICIENCY