Under the current Total Coliform Rule, repeat samples must be taken at the original sample location, plus at least one sample within 5 service connections upstream of the original sample location and at least one sample within 5 service connections downstream of the original sample location. If the original sample location is at the end of the distribution system or one away from the end of the distribution system, the state may waive the requirement of at least one of the upstream and downstream samples being within 5 service connections of the original sample location (although the sample must be collected elsewhere). In this case, the hydrants being considered for use for repeat sampling would have to be within 5 service connections upstream and downstream. The system could also consider dedicated sampling stations, as long as they meet the 5 upstream and downstream requirement.
Under the Revised Total Coliform Rule, which takes effect on April 1, 2016, systems must continue to meet this requirement. However, the state may allow for an alternative repeat monitoring location in lieu of the requirement that at least one of the repeat samples be collected within 5 service connections upstream and downstream – see 141.853(a)(5)(i). In this case, the system may propose an alternative repeat sampling location that the system believes is representative of a pathway for contamination to enter the distribution system. So, as of the effective date of the Revised Total Coliform Rule, sampling at the hydrants could be used as long as the locations are representative of a pathway for contaminant entry to the distribution system. Absent such a finding, hydrants upstream and downstream may only be used if they are within 5 service connections.
Generally, hydrants are not good sample locations and are not commonly used. Some systems have installed dedicated sampling stations to improve sampler security and access.