What is an important consideration when sampling chlorinated water?

When sampling chlorinated water, it is crucial to analyze the sample quickly to measure residual chlorine levels accurately. Chlorine, particularly in its free form, can dissipate from water samples over time due to various factors such as temperature and exposure to light. If the analysis is delayed, the chlorine concentration may decrease, leading to inaccurate results that do not reflect the actual chlorine levels in the water system at the time of sampling. Therefore, prompt analysis ensures that the residual chlorine measurements are reliable and can be used to assess water quality effectively.

The other considerations, while they may address various aspects of water sampling, do not hold the same significance in relation to chlorinated water, particularly regarding the stability and accuracy of chlorine measurements. Storing samples at room temperature may not preserve chlorine levels optimally, filtering is not necessarily required for samples intended to measure chlorine, and the time of sampling does not directly impact the residual chlorine measurement as long as the cover of appropriate protocols is maintained.