Drinking Water Right-to-Know Act of 1999

Drinking Water Right-to-Know Act of 1999 - Amends the Safe Drinking Water Act to require a national primary drinking water regulation for radionuclides to require the testing of drinking water for the presence of radium 224 no later than 48 hours after taking a sample.Requires annual consumer confidence reports by community water systems to include a report on the level of each contaminant that may be difficult to detect in finished water and present at levels that present a public health concern in such water. Requires regulations regarding such reports to direct public water systems to mail such reports to residential consumers and such reports suitable for posting to customers providing water to non-residential consumers.Provides that certain procedures for systems serving smaller communities that are not required to mail such report to consumers shall require such systems to notify consumers of new contamination or a significant increase in contamination by a regulated contaminant that is above the maximum contaminant level goal for the contaminant or of such contamination or increase by an unregulated contaminant.Requires State source water assessment programs to assess the susceptibility of each public water system in the delineated areas to any contaminant that is: (1) subject to a national primary drinking water regulation; (2) included on a specified list of unregulated contaminants; (3) the subject of a health advisory published by the Administrator of the Environmental Protection Agency; (4) monitored under such programs; (5) known or suspected to be from a pollution source; or (6) monitored by the U.S. Geological Survey under the National Water Quality Assessment program.Requires such programs to: (1) identify contaminants described in the preceding paragraph that the State determines present a public health threat; (2) require monitoring for such contaminants if a contaminant may have been released by a potentially significant source; (3) identify known or suspected sources of pollution that may threaten public health; (4) apply to wellheads, groundwater recharge areas, watersheds, and other areas determined to be appropriate; and (5) be developed, updated, and implemented in cooperation with the public served by the source water assessment areas included in such programs.Directs States to submit plans for such programs to the Administrator. Provides for plan updates every five years.