The Power of Information

National Drinking Water Database


City of Daly City Utilities - San Mateo, CA


Serves 92,311 people

Chlorine dioxide

Chlorine dioxide is used as drinking water disinfection agent and as a bleaching agent for cellulose, paper pulp, flour and oils; in water, it rapidly decomposes into toxic disinfection byproducts chlorite and chlorate.
 
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
14 days
Tests ConductedNumber of individual tests done for this contaminant
14 tests

Testing Summary

ContaminantAverage/
Maximum
Result
Health Limit
Exceeded
Legal Limit
Exceeded

Testing History

-Tested      -Detected      -Over Health Guidelines      -Over Legal Limit*
Chlorine dioxideChlorine dioxide is used as drinking water disinfection agent and as a bleaching agent for cellulose, paper pulp, flour and oils; in water, it rapidly decomposes into toxic disinfection byproducts chlorite and chlorate.57.14 ppb
190 ppb
No
800 ppb
Legal at any levelThis is the Federal Limit. State Limits may be lower.
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 Chlorine dioxide

Health Based Limits for Chlorine dioxide

StandardDescriptionLevel
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.800 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.840 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.840 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.1000 ppb

Testing Results

Testing DateAverage
Result
Samples taken that dayNumber of Non-DetectsRange of Results
2005-07-0690 ppb1090 ppb
2005-07-01110 ppb10110 ppb
2005-06-3060 ppb1060 ppb
2005-06-290 ppb110 ppb
2005-06-2860 ppb1060 ppb
2005-06-2460 ppb1060 ppb
2005-06-2340 ppb1040 ppb
2005-06-2250 ppb1050 ppb
2005-06-210 ppb110 ppb
2005-06-170 ppb110 ppb
2005-06-16190 ppb10190 ppb
2005-06-130 ppb110 ppb
2005-06-12140 ppb10140 ppb
2005-06-110 ppb110 ppb