Next, you need to find out your Peak Historical month of testing. According to the EPA, the Peak Historical month is the month with the highest TTHM or the highest HAA5 levels or the warmest water temperature, which represents your worst-case scenario for DBP formation. Note that the Standard Monitoring collection sites cannot be the same collection sites used in Stage 1 monitoring. The samples must be collected from distribution rather than source or treatment plant. Download the Standard Monitoring Requirements to determine your monitoring frequency and the number of collection sites. *The EPA says if you have more sites than required, then choose entry points with the highest flows. If you have fewer sites than required, then replace additional sites with TTHM and HAA5 sites.