Water

A single laboratory result may not describe conditions throughout a water system or across the period being disputed. An expert can compare sampling location, timing, collection method, laboratory procedures, detection limits, treatment conditions, and trends across repeated measurements. The analysis may also distinguish source-water conditions from changes occurring during treatment or distribution.

Filtration records can show how a treatment system handled particles or targeted constituents, while disinfectant data may provide information about microbial-control practices and conditions within the distribution system. Equipment settings, filter runs, pressure or flow data, chemical-feed rates, residual measurements, maintenance, and water-quality results can be examined together. EPA notes that many surface-water systems use disinfection and maintain a disinfectant residual in the distribution system to reduce microbial risks.

Water-use records can help quantify water withdrawals, deliveries, metered use, or other water use during a relevant period and, where supported by appropriate data and methods, may also help evaluate consumptive use. Meter data, billing records, production information, pumping records, flow measurements, and historical usage can be compared for inconsistencies or changes over time. USGS treats withdrawals and consumptive use as distinct measures and maintains water-use information across public supply, industrial, irrigation, domestic self-supply, and other categories.