The Power of Information

National Drinking Water Database


City of Napa Utilities - Napa, CA


Serves 70,000 people

Chloroform

Chloroform is a disinfection byproduct from the trihalomethane (THM) family, and is formed when chlorine, chloramines or other disinfectants react with organic and inorganic matter in water.
 
This Drinking Water System
Test Days Exceeding Health GuidelinesDefinition of what this is
56 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
58 days
Tests ConductedNumber of individual tests done for this contaminant
488 tests

Testing Summary

ContaminantAverage/
Maximum
Result
Health Limit
Exceeded
Legal Limit
Exceeded

Testing History

-Tested      -Detected      -Over Health Guidelines      -Over Legal Limit*
ChloroformChloroform is a disinfection byproduct from the trihalomethane (THM) family, and is formed when chlorine, chloramines or other disinfectants react with organic and inorganic matter in water.35.59 ppb
76.75 ppb
Yes
5.7 ppb
No
80 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 Chloroform

Health Based Limits for Chloroform

StandardDescriptionLevel
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.5.7 ppb
Drinking Water Equivalent LevelA lifetime exposure concentration protective of adverse, noncarcinogenic health effects, that assumes all of the exposure to a contaminant is from drinking water. Source: U.S. Environmental Protection Agency.35 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.70 ppb
Lifetime health-based limit, non-cancer riskConcentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic health effects for a lifetime of exposure. The Lifetime health-based limit (or Health Advisory, HA) is based on exposure for a a 70-kg adult consuming 2 liters of water per day. Source: U.S. Environmental Protection Agency.70 ppb
Maximum Contaminant Limit (MCL)The enforceable standard which defines the highest level of a contaminant that is allowed in drinking water. MCLs are set as close to health-based limits (Maximum Contaminant Level Goals, or MCLGs) as feasible using the best available analytical and treatment technologies and taking cost into consideration. Source: U.S. Environmental Protection Agency.80 ppb
Children's health-based limit for 1-day exposureConcentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic health effects for up to one day of exposure. The One-Day health-based limit (or Health Advisory, HA) is typically set to protect a 10-kg child consuming 1 liter of water per day. Source: U.S. Environmental Protection Agency.4000 ppb
Children's health-based limit for 10-day exposureConcentration of a chemical in drinking water that is not expected to cause any adverse, noncarcinogenic effects for up to ten days of exposure. The Ten-Day health-based limit (or Health Advisory, HA) is typically set to protect a 10-kg child consuming 1 liter of water per day. Source: U.S. Environmental Protection Agency.4000 ppb

Testing Results

Testing DateAverage
Result
Samples taken that dayNumber of Non-DetectsRange of Results
2009-03-1737.25 ppb4023 to 47 ppb
2009-03-0411 ppb1011 ppb
2009-02-0431.64 ppb1702.8 to 53 ppb
2009-01-0730.78 ppb502.9 to 43 ppb
2008-12-0324.07 ppb2102.5 to 59 ppb
2008-11-0546.14 ppb1020 to 87 ppb
2008-10-0147.96 ppb3002.2 to 120 ppb
2008-09-0342.43 ppb1702.3 to 89 ppb
2008-08-0653.66 ppb3105.7 to 140 ppb
2008-07-167.2 ppb107.2 ppb
2008-07-0944.2 ppb1007 to 72 ppb
2008-06-0437.83 ppb2610 to 89 ppb
2008-05-0744.25 ppb8020 to 58 ppb
2008-04-0231.81 ppb1610 to 44 ppb
2008-03-0576.75 ppb4071 to 84 ppb
2008-02-0660.5 ppb4053 to 73 ppb
2008-01-0919.12 ppb503.6 to 24 ppb
2007-12-0521.25 ppb4014 to 26 ppb
2007-11-0718.13 ppb8011 to 25 ppb
2007-10-0336.08 ppb12025 to 46 ppb
2007-09-0549.5 ppb12038 to 60 ppb
2007-08-0146.25 ppb12028 to 56 ppb
2007-07-1639.45 ppb1502.8 to 63 ppb
2007-06-0629.39 ppb1004.9 to 44 ppb
2007-05-0233.75 ppb8030 to 38 ppb
2007-04-0427.5 ppb4020 to 38 ppb
2007-03-0732 ppb3024 to 41 ppb
2007-02-0733.5 ppb4029 to 38 ppb
2007-01-0321.75 ppb4018 to 30 ppb
2006-12-0635 ppb4016 to 61 ppb
2006-11-0845.5 ppb4026 to 63 ppb
2006-10-0447.75 ppb8023 to 69 ppb
2006-09-0644.83 ppb6034 to 62 ppb
2006-08-232.15 ppb210 to 4.3 ppb
2006-08-0241.13 ppb8028 to 60 ppb
2006-07-0526.51 ppb1010 to 52 ppb
2006-06-0731.5 ppb8015 to 45 ppb
2006-05-0350.75 ppb4023 to 70 ppb
2006-03-0129 ppb4018 to 35 ppb
2005-12-0723.25 ppb4021 to 24 ppb
2005-11-0941.25 ppb4023 to 48 ppb
2005-10-0539.17 ppb12027 to 56 ppb
2005-07-203 ppb103 ppb
2005-06-0143.5 ppb8025 to 60 ppb
2005-05-0432.25 ppb4020 to 43 ppb
2005-04-0649.25 ppb4029 to 65 ppb
2005-03-0256.25 ppb4052 to 62 ppb
2005-02-0269 ppb4062 to 76 ppb
2005-01-0535.25 ppb4025 to 46 ppb
2004-12-0824.5 ppb4018 to 31 ppb
2004-11-1030.5 ppb4023 to 38 ppb
2004-10-0640.38 ppb8028 to 62 ppb
2004-09-0126.75 ppb12021 to 34 ppb
2004-08-0225.11 ppb1302.4 to 45 ppb
2004-07-1435.46 ppb13021 to 53 ppb
2004-06-0235.56 ppb9016 to 93 ppb
2004-05-1232.25 ppb8020 to 41 ppb
2004-04-0732.5 ppb4022 to 40 ppb