Laboratories participating in SDWIS analyze water samples for TTHMs according to methods approved by U.S.
The incomplete data and reporting delays described under the heading "Data Quality" suggest that intended participants may lack willingness to participate in SDWIS.
Incomplete data, variability in data collection, and delays in data reporting as described under "Data Quality" suggest that SDWIS may not be detecting all TTHM violations and enforcement actions.
The quality of SDWIS laboratory analyses as described under the heading "Simplicity" is likely to result in reports of TTHM level violations that are truly violations.
SDWIS covers the specified population/region of more than 172,000 public water systems facilities that serve more than 90 percent of the U.S.
Data on TTHM levels in drinking water and enforcement actions for noncompliant TTHM levels are reported in SDWIS on a quarterly basis.
SDWIS is a stable system that has demonstrated the ongoing ability to produce information and adapt to changes as described under the heading "Flexibility" The reliability and availability of the system for public health surveillance are affected, however, by variability in data collection, reporting delays, and incomplete data.
Data on noncompliant TTHM levels are limited for public health surveillance because the type and impact of enforcement action are not reported to SDWIS. SDWIS has two strengths for measuring TTHMs.
SDWIS is an example of an existing environmental data system that is potentially useful for public health surveillance.
Evaluation of the Environmental Protection Agency's safe drinking water information system (SDWIS).