Public Water System: Arizona Water Co - Overgaard

MyTapWater.org's tap water quality report is the compilation of data collected from federal, state, and local government agencies, most prominently the EPA. We strive to populate the report with the latest data concerning water contaminants, lead and copper levels, and water quality violations. We only collect drinking water data from public water systems.

PWS Service Information
PWS ID: AZ0409004
Type: Community water system
EPA Region: 09
Primary Service Area: Residential Area
Primary Source: Ground water
Population Served: 10,426
Contact Information
LYNDE, REGINA
LYNDE, REGINA
ARIZONA WATER CO
3805 N BLACK CANYON HWY
PHOENIX, AZ 85015-5351

This public water system services 1 zip code in 1 municipality in 1 county.

Summary Results


A summary view of the the times a water contaminant was tested and found to exceed the level set by the EPA (the MCL).

Maximum Contaminant Levels Exceeded (by year):

2013   (1) 2014   (0) 2015   (0)
chlorate

Contaminant Detailed Results


This a view of violations of maximum contaminant levels. In the expanded view you can see each know test date for a given contaminant, the result of the test, the minimum level that can be recognized in a test (MRL), and upper limit that is considered healthy (HRL).

chlorate
Is this in your home's pipes?

Year Test Date MRL HRL Test Result
2013 2013-12-11 20 210 < 20
2013 2013-12-11 20 210 < 20
2013 2013-12-11 20 210 < 20
2013 2013-12-11 20 210 400
2013 2013-12-11 20 210 240
2013 2013-12-11 20 210 160
2013 2013-12-11 20 210 250
2013 2013-12-11 20 210 300
2013 2013-12-11 20 210 < 20
2013 2013-12-11 20 210 < 20
2013 2013-06-25 20 210 < 20
2013 2013-06-25 20 210 < 20
2013 2013-06-25 20 210 150
2013 2013-06-25 20 210 62
2013 2013-06-25 20 210 61
2013 2013-06-25 20 210 < 20
2013 2013-06-25 20 210 190
2013 2013-06-25 20 210 170
2013 2013-06-25 20 210 < 20
2013 2013-06-25 20 210 < 20

Other Water Contaminants Tested


The following contaminants were tested and within national EPA guidelines.

The last mile of pipe makes a big difference, learn more about testing your water.

Contaminant MRL HRL Avg Result
chromium-6 0.03 0 0.933 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-11 0.03 0 1.1
2013 2013-12-11 0.03 0 1.1
2013 2013-12-11 0.03 0 1.1
2013 2013-12-11 0.03 0 0.93
2013 2013-12-11 0.03 0 0.13
2013 2013-12-11 0.03 0 0.72
2013 2013-12-11 0.03 0 0.94
2013 2013-12-11 0.03 0 1.2
2013 2013-12-11 0.03 0 0.62
2013 2013-12-11 0.03 0 0.51
2013 2013-09-09 0.03 0 0.82
2013 2013-07-15 0.03 0 0.98
2013 2013-07-15 0.03 0 1.2
2013 2013-06-25 0.03 0 0.67
2013 2013-06-25 0.03 0 1.3
2013 2013-06-25 0.03 0 1.1
2013 2013-06-25 0.03 0 0.94
2013 2013-06-25 0.03 0 1.2
2013 2013-06-25 0.03 0 1.1
2013 2013-06-25 0.03 0 1
PFHpA 0.01 0 < 0.01 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-11 0.01 0 < 0.01
2013 2013-12-11 0.01 0 < 0.01
2013 2013-12-11 0.01 0 < 0.01
2013 2013-12-11 0.01 0 < 0.01
2013 2013-12-11 0.01 0 < 0.01
2013 2013-06-25 0.01 0 < 0.01
2013 2013-06-25 0.01 0 < 0.01
2013 2013-06-25 0.01 0 < 0.01
2013 2013-06-25 0.01 0 < 0.01
2013 2013-06-25 0.01 0 < 0.01
chloromethane 0.2 2.69 < 0.2 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-11 0.2 2.69 < 0.2
2013 2013-12-11 0.2 2.69 < 0.2
2013 2013-12-11 0.2 2.69 < 0.2
2013 2013-12-11 0.2 2.69 < 0.2
2013 2013-12-11 0.2 2.69 < 0.2
2013 2013-06-25 0.2 2.69 < 0.2
2013 2013-06-25 0.2 2.69 < 0.2
2013 2013-06-25 0.2 2.69 < 0.2
2013 2013-06-25 0.2 2.69 < 0.2
2013 2013-06-25 0.2 2.69 < 0.2
HCFC-22 0.08 0 < 0.08 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-11 0.08 0 < 0.08
2013 2013-12-11 0.08 0 < 0.08
2013 2013-12-11 0.08 0 < 0.08
2013 2013-12-11 0.08 0 < 0.08
2013 2013-12-11 0.08 0 < 0.08
2013 2013-06-25 0.08 0 < 0.08
2013 2013-06-25 0.08 0 < 0.08
2013 2013-06-25 0.08 0 < 0.08
2013 2013-06-25 0.08 0 < 0.08
2013 2013-06-25 0.08 0 < 0.08
strontium 0.3 1500 100.25 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2014 2014-01-27 0.3 1500 60
2014 2014-01-27 0.3 1500 120
2013 2013-12-11 0.3 1500 62
2013 2013-12-11 0.3 1500 110
2013 2013-12-11 0.3 1500 100
2013 2013-12-11 0.3 1500 110
2013 2013-12-11 0.3 1500 100
2013 2013-12-11 0.3 1500 120
2013 2013-12-11 0.3 1500 74
2013 2013-12-11 0.3 1500 140
2013 2013-10-07 0.3 1500 65
2013 2013-08-20 0.3 1500 120
2013 2013-08-20 0.3 1500 140
2013 2013-08-20 0.3 1500 120
2013 2013-06-25 0.3 1500 74
2013 2013-06-25 0.3 1500 61
2013 2013-06-25 0.3 1500 120
2013 2013-06-25 0.3 1500 69
2013 2013-06-25 0.3 1500 130
2013 2013-06-25 0.3 1500 110
PFNA 0.02 0 < 0.02 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-11 0.02 0 < 0.02
2013 2013-12-11 0.02 0 < 0.02
2013 2013-12-11 0.02 0 < 0.02
2013 2013-12-11 0.02 0 < 0.02
2013 2013-12-11 0.02 0 < 0.02
2013 2013-06-25 0.02 0 < 0.02
2013 2013-06-25 0.02 0 < 0.02
2013 2013-06-25 0.02 0 < 0.02
2013 2013-06-25 0.02 0 < 0.02
2013 2013-06-25 0.02 0 < 0.02
PFOS 0.04 0.07 < 0.04 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-11 0.04 0.07 < 0.04
2013 2013-12-11 0.04 0.07 < 0.04
2013 2013-12-11 0.04 0.07 < 0.04
2013 2013-12-11 0.04 0.07 < 0.04
2013 2013-12-11 0.04 0.07 < 0.04
2013 2013-06-25 0.04 0.07 < 0.04
2013 2013-06-25 0.04 0.07 < 0.04
2013 2013-06-25 0.04 0.07 < 0.04
2013 2013-06-25 0.04 0.07 < 0.04
2013 2013-06-25 0.04 0.07 < 0.04
1,4-dioxane 0.07 0.35 < 0.07 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-11 0.07 0.35 < 0.07
2013 2013-12-11 0.07 0.35 < 0.07
2013 2013-12-11 0.07 0.35 < 0.07
2013 2013-12-11 0.07 0.35 < 0.07
2013 2013-12-11 0.07 0.35 < 0.07
2013 2013-06-25 0.07 0.35 < 0.07
2013 2013-06-25 0.07 0.35 < 0.07
2013 2013-06-25 0.07 0.35 < 0.07
2013 2013-06-25 0.07 0.35 < 0.07
2013 2013-06-25 0.07 0.35 < 0.07
PFOA 0.02 0.07 < 0.02 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-11 0.02 0.07 < 0.02
2013 2013-12-11 0.02 0.07 < 0.02
2013 2013-12-11 0.02 0.07 < 0.02
2013 2013-12-11 0.02 0.07 < 0.02
2013 2013-12-11 0.02 0.07 < 0.02
2013 2013-06-25 0.02 0.07 < 0.02
2013 2013-06-25 0.02 0.07 < 0.02
2013 2013-06-25 0.02 0.07 < 0.02
2013 2013-06-25 0.02 0.07 < 0.02
2013 2013-06-25 0.02 0.07 < 0.02
PFHxS 0.03 0 < 0.03 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-11 0.03 0 < 0.03
2013 2013-12-11 0.03 0 < 0.03
2013 2013-12-11 0.03 0 < 0.03
2013 2013-12-11 0.03 0 < 0.03
2013 2013-12-11 0.03 0 < 0.03
2013 2013-06-25 0.03 0 < 0.03
2013 2013-06-25 0.03 0 < 0.03
2013 2013-06-25 0.03 0 < 0.03
2013 2013-06-25 0.03 0 < 0.03
2013 2013-06-25 0.03 0 < 0.03
1,2,3-trichloropropane 0.03 0.0004 < 0.03 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-11 0.03 0.0004 < 0.03
2013 2013-12-11 0.03 0.0004 < 0.03
2013 2013-12-11 0.03 0.0004 < 0.03
2013 2013-12-11 0.03 0.0004 < 0.03
2013 2013-12-11 0.03 0.0004 < 0.03
2013 2013-06-25 0.03 0.0004 < 0.03
2013 2013-06-25 0.03 0.0004 < 0.03
2013 2013-06-25 0.03 0.0004 < 0.03
2013 2013-06-25 0.03 0.0004 < 0.03
2013 2013-06-25 0.03 0.0004 < 0.03
PFBS 0.09 0 < 0.09 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-11 0.09 0 < 0.09
2013 2013-12-11 0.09 0 < 0.09
2013 2013-12-11 0.09 0 < 0.09
2013 2013-12-11 0.09 0 < 0.09
2013 2013-12-11 0.09 0 < 0.09
2013 2013-06-25 0.09 0 < 0.09
2013 2013-06-25 0.09 0 < 0.09
2013 2013-06-25 0.09 0 < 0.09
2013 2013-06-25 0.09 0 < 0.09
2013 2013-06-25 0.09 0 < 0.09
chromium 0.2 100 1.025 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2014 2014-01-27 0.2 100 1.4
2014 2014-01-27 0.2 100 1.1
2013 2013-12-11 0.2 100 0.8
2013 2013-12-11 0.2 100 1
2013 2013-12-11 0.2 100 1
2013 2013-12-11 0.2 100 1
2013 2013-12-11 0.2 100 0.9
2013 2013-12-11 0.2 100 1.3
2013 2013-12-11 0.2 100 1.1
2013 2013-12-11 0.2 100 1
2013 2013-10-07 0.2 100 1.1
2013 2013-08-20 0.2 100 0.9
2013 2013-08-20 0.2 100 0.9
2013 2013-08-20 0.2 100 1.1
2013 2013-06-25 0.2 100 0.7
2013 2013-06-25 0.2 100 1.2
2013 2013-06-25 0.2 100 0.9
2013 2013-06-25 0.2 100 0.9
2013 2013-06-25 0.2 100 1.1
2013 2013-06-25 0.2 100 1.1
molybdenum 1 40 < 1 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2014 2014-01-27 1 40 < 1
2014 2014-01-27 1 40 < 1
2013 2013-12-11 1 40 < 1
2013 2013-12-11 1 40 < 1
2013 2013-12-11 1 40 < 1
2013 2013-12-11 1 40 < 1
2013 2013-12-11 1 40 < 1
2013 2013-12-11 1 40 < 1
2013 2013-12-11 1 40 < 1
2013 2013-12-11 1 40 < 1
2013 2013-10-07 1 40 < 1
2013 2013-08-20 1 40 < 1
2013 2013-08-20 1 40 < 1
2013 2013-08-20 1 40 < 1
2013 2013-06-25 1 40 < 1
2013 2013-06-25 1 40 < 1
2013 2013-06-25 1 40 < 1
2013 2013-06-25 1 40 < 1
2013 2013-06-25 1 40 < 1
2013 2013-06-25 1 40 < 1
bromomethane 0.2 140 < 0.2 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-11 0.2 140 < 0.2
2013 2013-12-11 0.2 140 < 0.2
2013 2013-12-11 0.2 140 < 0.2
2013 2013-12-11 0.2 140 < 0.2
2013 2013-12-11 0.2 140 < 0.2
2013 2013-06-25 0.2 140 < 0.2
2013 2013-06-25 0.2 140 < 0.2
2013 2013-06-25 0.2 140 < 0.2
2013 2013-06-25 0.2 140 < 0.2
2013 2013-06-25 0.2 140 < 0.2
1,3-butadiene 0.1 0.0103 < 0.1 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-11 0.1 0.0103 < 0.1
2013 2013-12-11 0.1 0.0103 < 0.1
2013 2013-12-11 0.1 0.0103 < 0.1
2013 2013-12-11 0.1 0.0103 < 0.1
2013 2013-12-11 0.1 0.0103 < 0.1
2013 2013-06-25 0.1 0.0103 < 0.1
2013 2013-06-25 0.1 0.0103 < 0.1
2013 2013-06-25 0.1 0.0103 < 0.1
2013 2013-06-25 0.1 0.0103 < 0.1
2013 2013-06-25 0.1 0.0103 < 0.1
1,1-dichloroethane 0.03 6.14 < 0.03 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-11 0.03 6.14 < 0.03
2013 2013-12-11 0.03 6.14 < 0.03
2013 2013-12-11 0.03 6.14 < 0.03
2013 2013-12-11 0.03 6.14 < 0.03
2013 2013-12-11 0.03 6.14 < 0.03
2013 2013-06-25 0.03 6.14 < 0.03
2013 2013-06-25 0.03 6.14 < 0.03
2013 2013-06-25 0.03 6.14 < 0.03
2013 2013-06-25 0.03 6.14 < 0.03
2013 2013-06-25 0.03 6.14 < 0.03
Halon 1011 0.06 90 < 0.06 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2013 2013-12-11 0.06 90 < 0.06
2013 2013-12-11 0.06 90 < 0.06
2013 2013-12-11 0.06 90 < 0.06
2013 2013-12-11 0.06 90 < 0.06
2013 2013-12-11 0.06 90 < 0.06
2013 2013-06-25 0.06 90 < 0.06
2013 2013-06-25 0.06 90 < 0.06
2013 2013-06-25 0.06 90 < 0.06
2013 2013-06-25 0.06 90 < 0.06
2013 2013-06-25 0.06 90 < 0.06
cobalt 1 70 < 1 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2014 2014-01-27 1 70 < 1
2014 2014-01-27 1 70 < 1
2013 2013-12-11 1 70 < 1
2013 2013-12-11 1 70 < 1
2013 2013-12-11 1 70 < 1
2013 2013-12-11 1 70 < 1
2013 2013-12-11 1 70 < 1
2013 2013-12-11 1 70 < 1
2013 2013-12-11 1 70 < 1
2013 2013-12-11 1 70 < 1
2013 2013-10-07 1 70 < 1
2013 2013-08-20 1 70 < 1
2013 2013-08-20 1 70 < 1
2013 2013-08-20 1 70 < 1
2013 2013-06-25 1 70 < 1
2013 2013-06-25 1 70 < 1
2013 2013-06-25 1 70 < 1
2013 2013-06-25 1 70 < 1
2013 2013-06-25 1 70 < 1
2013 2013-06-25 1 70 < 1
vanadium 0.2 21 1.91 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2014 2014-01-27 0.2 21 1.5
2014 2014-01-27 0.2 21 2.1
2013 2013-12-11 0.2 21 1.7
2013 2013-12-11 0.2 21 2
2013 2013-12-11 0.2 21 1.5
2013 2013-12-11 0.2 21 1
2013 2013-12-11 0.2 21 2
2013 2013-12-11 0.2 21 2.2
2013 2013-12-11 0.2 21 1.6
2013 2013-12-11 0.2 21 2.4
2013 2013-10-07 0.2 21 1.9
2013 2013-08-20 0.2 21 2.2
2013 2013-08-20 0.2 21 2.2
2013 2013-08-20 0.2 21 2.4
2013 2013-06-25 0.2 21 1.8
2013 2013-06-25 0.2 21 1.5
2013 2013-06-25 0.2 21 2.2
2013 2013-06-25 0.2 21 2.2
2013 2013-06-25 0.2 21 2
2013 2013-06-25 0.2 21 1.8

Lead and Copper Data


Lead and copper are recorded separately from other contaminants because of the Lead and Copper Rule. As with all other results, these are the findings at the water supply. Lead and copper can be — and often are — added to drinking water in between the water facility and a tap.

Sample ID Contaminant Sampling Start Date Sampling End Date Result
AZ24740 lead 2014-01-01 2016-12-31 0.0039mg/L
AZ18957 lead 2011-01-01 2013-12-31 0.005mg/L
AZ12784 lead 2009-01-01 2011-12-31 0.004mg/L

Violations


Known violations of the Safe Drinking Water Act as recorded by the EPA.

Compliance Dates Rule Violation Type Contaminant Name Status
2015-10-01 - 2015-12-31 Stage 1 Disinfectants and Disinfection Byproducts Rule Monitoring and Reporting (DBP) Chlorine Returned to Compliance
2009-01-01 - 2009-12-31 Nitrates Monitoring, Regular Nitrate Returned to Compliance
2009-04-01 - 2009-04-30 Total Coliform Rule Monitoring, Routine Major (TCR) Coliform (TCR) Returned to Compliance
2007-07-01 - 2007-09-30 Stage 1 Disinfectants and Disinfection Byproducts Rule Monitoring and Reporting (DBP) Chlorine Returned to Compliance
2006-08-01 - 2006-08-31 Total Coliform Rule Monitoring, Routine Minor (TCR) Coliform (TCR) Returned to Compliance
2005-03-01 - 2005-03-31 Total Coliform Rule Monitoring, Repeat Major (TCR) Coliform (TCR) Returned to Compliance
2004-01-01 - 2004-12-31 Stage 1 Disinfectants and Disinfection Byproducts Rule Monitoring and Reporting (DBP) TTHM Returned to Compliance
2004-01-01 - 2004-12-31 Stage 1 Disinfectants and Disinfection Byproducts Rule Monitoring and Reporting (DBP) Total Haloacetic Acids (HAA5) Returned to Compliance
2004-01-01 - 2004-03-31 Stage 1 Disinfectants and Disinfection Byproducts Rule Monitoring and Reporting (DBP) Chlorine Returned to Compliance
2003-01-01 - 2003-12-31 Synthetic Organic Chemicals Monitoring, Regular Benzo(a)pyrene Returned to Compliance
2003-01-01 - 2003-12-31 Synthetic Organic Chemicals Monitoring, Regular Pentachlorophenol Returned to Compliance
2003-01-01 - 2003-12-31 Synthetic Organic Chemicals Monitoring, Regular 1,2-DIBROMO-3-CHLOROPROPANE Returned to Compliance
2003-01-01 - 2003-12-31 Synthetic Organic Chemicals Monitoring, Regular ETHYLENE DIBROMIDE Returned to Compliance
2003-01-01 - 2003-12-31 Synthetic Organic Chemicals Monitoring, Regular Chlordane Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular Methoxychlor Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular 1,2-DIBROMO-3-CHLOROPROPANE Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular ETHYLENE DIBROMIDE Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular Chlordane Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular Toxaphene Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular Endrin Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular Diquat Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular Endothall Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular Di(2-ethylhexyl) adipate Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular OXAMYL Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular Simazine Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular Di(2-ethylhexyl) phthalate Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular Picloram Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular BHC-GAMMA Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular Dinoseb Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular Hexachlorocyclopentadiene Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular Carbofuran Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular Atrazine Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular LASSO Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular Heptachlor Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular Heptachlor epoxide Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular 2,4-D Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular 2,4,5-TP Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular HEXACHLOROBENZENE Returned to Compliance
2000-01-01 - 2000-12-31 Synthetic Organic Chemicals Monitoring, Regular Benzo(a)pyrene Returned to Compliance
2002-07-01 - N/A Consumer Confidence Rule Consumer Confidence Report Complete Failure to Report Consumer Confidence Rule Returned to Compliance
2004-07-01 - N/A Consumer Confidence Rule Consumer Confidence Report Complete Failure to Report Consumer Confidence Rule Returned to Compliance

What My Water Data Means


Water data isn't always easy to interpret, but by following the links on this page you should be able to have most of your questions answered. By clicking the name of a water contaminant or secondary substance you can learn about that specific substance. Ultimately this page should give you some insight towards learning if your water is safe, what water filter you should buy (if any), and how well your local water compares against other sources.

Sources


The origin of MyTapWater.org's water data is explained on our Data Sources page.

Why Is My Water Data Not More Recent?


The recency of the data for your ZIP code depends on the last your water source was tested, by a federal, state, or local agency. More information about the timing can be determined by learning about the dataset in question and seeing how often the EPA (other another governing body) mandated testing.