Protocol for the Collection, Transfer and ANSI/AARST MW-RN 2020 Measurement of Radon in Water 23 Table 8. 5 .2 For Concentrations of Radon in Water That are Less Than 4,000 pCi/L (150 Bq/L) (or a lower action level recommended by local jurisdiction or state health department). EQUIVALENT STATEMENTS FOR THESE ADVISORIES SHALL TO BE INCLUDED IN THE REPORT • Consider mitigation if radon in water test results indicate radon concentrations greater than half the action level. • Confirm low test results if samples were collected under unusual temporary conditions such as: - If the building was vacant when initial sample collection is conducted, repeat the collection with 30 days after occupancy if the water supply has not passed through a municipal treatment facility. - If initial sample collection is conducted during unusual flood or drought conditions, repeat the measurement under more typical water table conditions. • Confirm low test results by repeating tests during different seasons and weather conditions. If no seasonal variation is measured, retest radon in water at least every 5 years. • In addition, be certain to test again when any of the following circumstances occur: - modifications are made to the well, pump or water treatment systems. - modifications are made to a radon-in-water mitigation system. 8. 6 All reports—Other health guidance advisories The test report shall also include equivalent statements for each of the following statements shown in Table 8. 6 . Table 8. 6 Other Health Guidance Advisories EQUIVALENT STATEMENTS FOR THESE ADVISORIES SHALL TO BE INCLUDED IN THE REPORT • The EPA recommends that all homes and buildings be tested for radon in indoor air. The quantity of radon in air that often comes from soil is not identified by a measurement of radon in water. • Treatment of potable water for bacteria should always be an important consideration (e.g., ultraviolet light, chlorination). • Measurement of gross alpha (GA) activity is another consideration to reveal if there are other dissolved radioisotopes in the water, such as radium and uranium. • Radium-bearing scaling can sometimes occur inside the pipes of a water system. Such an occurrence can be revealed by comparing radon levels in water samples collected prior to flushing the water system with those collected after flushing the system. • Other contaminants in the water may impact the function of a radon in water mitigation system. To make sure the radon water mitigation system functions as intended, it may be necessary to test the water for other contaminants and also treat the water for those other contaminants.