Purity of ultrapure water in a beaker does not match the purity on the water system display

This article addresses the misconception that a discrepancy between the purity of ultrapure water in a beaker and the water system display indicates a problem with the water system. The purity can change rapidly after being dispensed due to CO2 absorption, forming carbonic acid and lowering purity. To verify water purity accurately, it is best to use an inline conductivity meter with a flow cell. Consistent maintenance of the water system is recommended to avoid inaccurate results and downtime