Frequent Questions

Our water district has a number of wells that are operated on an as-needed basis. If we wouldn't otherwise run the wells except during a short amount of time, are we required to turn the wells on just to collect the scheduled samples for UCMR3?

For UCMR sampling, the regulations in 40 CFR 141.35(a)(v)(ii)(c) require samples to be taken at the entry point to the distribution system. As specified in footnote f of Table 1 in 40 CFR 141.40, entry points to the distribution system (EPTDS) are after treatment.

For further questions regarding UCMR3, please contact the UCMR Message Center at 1-800-949-1581 or at

Have more questions? Submit a request