The Power of Information

National Drinking Water Database

City of Modesto Utilities - Modesto, CA

Serves 190,106 people


Copper is a naturally occuring metal and drinking water contaminant that enters tap water by corrosion of household plumbing systems and erosion of natural deposits.
This Drinking Water System
Test Days Exceeding Health GuidelinesDefinition of what this is
0 days
Test Days Exceeding Legal LimitsNumber of days in which the samples taken in that day exceed the Maximum Contaminant Level (Depending on the contaminant and its MCL, that may or may not trigger an MCL violation. Some MCLs are based on averages spanning several months to a year)
0 days
Test DaysNumber of days in which this chemical has reported results in the data we received from the State
114 days
Tests ConductedNumber of individual tests done for this contaminant
172 tests

Testing Summary

Health Limit
Legal Limit

Testing History

-Tested      -Detected      -Over Health Guidelines      -Over Legal Limit*
CopperCopper is a naturally occuring metal and drinking water contaminant that enters tap water by corrosion of household plumbing systems and erosion of natural deposits.0 ppb
0 ppb
300 ppb
1000 ppb
NOTE: Each dot in the above graph represents one month.
* Water utilities are noted as exceeding the legal limit if any test is above the maximum contaminant level (MCL). Most MCLs are based on annual averages so exceeding the MCL for one test does not necessarily indicate that the system is out of compliance.

Health Based and Legal Limits for Copper

Health Based Limits for Copper

California Public Health GoalsDefined by the State of California Office of Environmental Health Hazard Assessment (OEHHA) as the level of contaminant that is allowed in drinking water. For acutely toxic substances, levels are set at which scientific evidence indicates that no known or anticipated adverse effects on health will occur, plus an adequate margin-of safety. PHGs for carcinogens or other substances which can cause chronic disease shall be based solely on health effects without regard to cost impacts and shall be set at levels which OEHHA has determined do not pose any significant risk to health.300 ppb
National Secondary Drinking Water RegulationsA National Secondary Drinking Water Regulation is a non-enforceable guideline regarding contaminants that may cause cosmetic effects (such as taste, odor, or color). Some states choose to adopt them as enforceable standards. Source: U.S. Environmental Protection Agency. 1000 ppb
Maximum Contaminant Limit Goal (MCLG)A non-enforceable health goal that is set at a level at which no known or anticipated adverse effect on the health of persons occurs and which allows an adequate margin of safety. Source: U.S. Environmental Protection Agency.1300 ppb
EPA Human Health Water Quality CriteriaWater quality criteria set by the US EPA provide guidance for states and tribes authorized to establish water quality standards under the Clean Water Act (CWA) to protect human health. These are non-enforceable standards based upon exposure by both drinking water and the contribution of water contamination to other consumed foods. Source: U.S. Environmental Protection Agency.1300 ppb

Testing Results

Testing DateAverage
Samples taken that dayNumber of Non-DetectsRange of Results
2009-03-240 ppb220 ppb
2009-03-170 ppb220 ppb
2009-03-100 ppb110 ppb
2009-03-030 ppb220 ppb
2009-02-190 ppb110 ppb
2009-02-100 ppb330 ppb
2008-12-180 ppb110 ppb
2008-11-120 ppb110 ppb
2008-08-120 ppb110 ppb
2008-06-240 ppb110 ppb
2008-06-170 ppb110 ppb
2008-06-120 ppb110 ppb
2008-06-100 ppb110 ppb
2008-06-030 ppb110 ppb
2008-05-220 ppb110 ppb
2008-05-130 ppb110 ppb
2008-05-060 ppb110 ppb
2008-04-290 ppb220 ppb
2008-04-230 ppb110 ppb
2008-04-220 ppb110 ppb
2008-04-080 ppb110 ppb
2008-03-270 ppb220 ppb
2008-03-180 ppb110 ppb
2008-03-060 ppb110 ppb
2008-02-140 ppb110 ppb
2008-01-290 ppb110 ppb
2008-01-220 ppb220 ppb
2008-01-150 ppb440 ppb
2007-12-180 ppb110 ppb
2007-11-280 ppb110 ppb
2007-11-150 ppb110 ppb
2007-10-160 ppb110 ppb
2007-07-240 ppb110 ppb
2007-06-180 ppb110 ppb
2007-05-240 ppb110 ppb
2007-05-150 ppb440 ppb
2007-04-170 ppb440 ppb
2007-04-160 ppb220 ppb
2007-04-100 ppb220 ppb
2007-04-040 ppb220 ppb
2007-04-020 ppb220 ppb
2007-03-150 ppb220 ppb
2007-03-140 ppb220 ppb
2007-03-070 ppb220 ppb
2007-02-140 ppb110 ppb
2007-02-070 ppb220 ppb
2007-02-060 ppb110 ppb
2006-12-200 ppb110 ppb
2006-12-190 ppb220 ppb
2006-12-070 ppb110 ppb
2006-11-210 ppb110 ppb
2006-11-150 ppb220 ppb
2006-07-250 ppb110 ppb
2006-07-180 ppb110 ppb
2006-06-280 ppb110 ppb
2006-06-210 ppb110 ppb
2006-05-170 ppb110 ppb
2006-05-030 ppb110 ppb
2006-04-040 ppb110 ppb
2006-03-280 ppb220 ppb
2006-03-220 ppb110 ppb
2006-03-080 ppb110 ppb
2006-02-280 ppb110 ppb
2006-02-210 ppb220 ppb
2006-02-150 ppb220 ppb
2006-02-140 ppb110 ppb
2006-02-070 ppb220 ppb
2005-11-220 ppb110 ppb
2005-11-080 ppb220 ppb
2005-10-190 ppb110 ppb
2005-09-010 ppb110 ppb
2005-08-250 ppb110 ppb
2005-07-270 ppb220 ppb
2005-07-260 ppb110 ppb
2005-07-130 ppb110 ppb
2005-07-060 ppb110 ppb
2005-06-280 ppb110 ppb
2005-06-160 ppb110 ppb
2005-06-150 ppb110 ppb
2005-06-080 ppb110 ppb
2005-05-250 ppb220 ppb
2005-05-240 ppb110 ppb
2005-05-190 ppb110 ppb
2005-05-100 ppb220 ppb
2005-04-260 ppb110 ppb
2005-04-190 ppb110 ppb
2005-04-130 ppb110 ppb
2005-04-120 ppb110 ppb
2005-03-170 ppb110 ppb
2005-03-100 ppb220 ppb
2005-02-170 ppb330 ppb
2005-02-030 ppb330 ppb
2005-01-270 ppb220 ppb
2005-01-200 ppb440 ppb
2005-01-130 ppb220 ppb
2005-01-060 ppb330 ppb
2004-12-300 ppb110 ppb
2004-12-090 ppb110 ppb
2004-11-180 ppb110 ppb
2004-11-040 ppb330 ppb
2004-10-140 ppb110 ppb
2004-10-070 ppb110 ppb
2004-09-160 ppb110 ppb
2004-09-090 ppb110 ppb
2004-08-120 ppb330 ppb
2004-06-070 ppb110 ppb
2004-04-150 ppb220 ppb
2004-04-080 ppb440 ppb
2004-03-110 ppb220 ppb
2004-03-040 ppb110 ppb
2004-02-120 ppb110 ppb
2004-02-050 ppb330 ppb
2004-01-150 ppb110 ppb
2004-01-080 ppb110 ppb