Jcsa - Central System Water System

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: VA3095490
Type: Community water system
EPA Region: 03
Primary Service Area: Residential Area
Primary Source: Ground water
Population Served: 51,137
Contact Information
POWELL, DOUGLAS
POWELL, DOUGLAS
119Tewning Road
WILLIAMSBURG, VA 23188-2639
[email protected]

This public water system services 1 county.

Summary Results


A summary view of tests in which a water contaminant found to exceed the Maximum Contaminant Level (MCL) set by the EPA.

Maximum Contaminant Levels Exceeded (by year):

2013   (0) 2014   (0) 2015   (1) 2016   (0) 2017   (0) 2018   (0)
chlorate

Contaminant Detailed Results


This a view of violations of maximum contaminant levels. Use the expanded view see result data for a drinking water contaminant, the minimum level that can be recognized in a test (MRL), and upper limit that is considered healthy (HRL).

chlorate

Year Test Date MRLMinimum Reporting Level HRLHealth Risk Limit Test Result
2015 2015-08-12 20 210 310
2015 2015-08-12 20 210 330
2015 2015-08-12 20 210 1400
2015 2015-08-12 20 210 660
2015 2015-08-11 20 210 1500
2015 2015-08-11 20 210 1400
2015 2015-08-11 20 210 1100
2015 2015-08-11 20 210 920
2015 2015-08-11 20 210 720
2015 2015-02-11 20 210 150
2015 2015-02-10 20 210 240
2015 2015-02-10 20 210 350
2015 2015-02-10 20 210 1700
2015 2015-02-10 20 210 210
2015 2015-02-09 20 210 170
2015 2015-02-09 20 210 210
2015 2015-02-09 20 210 240
2015 2015-02-09 20 210 180

Other Water Contaminants Tested


The following contaminants were tested and found to be within national EPA guidelines.

Contaminant MRLMinimum Reporting Level HRLHealth Risk Limit Avg Result
chromium 0.2 100 < 0.2 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-12 0.2 100 < 0.2
2015 2015-08-12 0.2 100 < 0.2
2015 2015-08-12 0.2 100 < 0.2
2015 2015-08-12 0.2 100 < 0.2
2015 2015-08-11 0.2 100 < 0.2
2015 2015-08-11 0.2 100 < 0.2
2015 2015-08-11 0.2 100 < 0.2
2015 2015-08-11 0.2 100 < 0.2
2015 2015-08-11 0.2 100 < 0.2
2015 2015-02-11 0.2 100 < 0.2
2015 2015-02-10 0.2 100 < 0.2
2015 2015-02-10 0.2 100 < 0.2
2015 2015-02-10 0.2 100 < 0.2
2015 2015-02-10 0.2 100 < 0.2
2015 2015-02-09 0.2 100 < 0.2
2015 2015-02-09 0.2 100 < 0.2
2015 2015-02-09 0.2 100 < 0.2
2015 2015-02-09 0.2 100 < 0.2
chromium-6 0.03 0 < 0.03 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-25 0.03 0 < 0.03
2015 2015-08-12 0.03 0 < 0.03
2015 2015-08-12 0.03 0 < 0.03
2015 2015-08-12 0.03 0 < 0.03
2015 2015-08-11 0.03 0 < 0.03
2015 2015-08-11 0.03 0 < 0.03
2015 2015-08-11 0.03 0 < 0.03
2015 2015-08-11 0.03 0 < 0.03
2015 2015-08-11 0.03 0 < 0.03
2015 2015-02-19 0.03 0 < 0.03
2015 2015-02-11 0.03 0 < 0.03
2015 2015-02-10 0.03 0 < 0.03
2015 2015-02-10 0.03 0 < 0.03
2015 2015-02-10 0.03 0 < 0.03
2015 2015-02-10 0.03 0 < 0.03
2015 2015-02-09 0.03 0 < 0.03
2015 2015-02-09 0.03 0 < 0.03
2015 2015-02-09 0.03 0 < 0.03
cobalt 1 70 < 1 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-12 1 70 < 1
2015 2015-08-12 1 70 < 1
2015 2015-08-12 1 70 < 1
2015 2015-08-12 1 70 < 1
2015 2015-08-11 1 70 < 1
2015 2015-08-11 1 70 < 1
2015 2015-08-11 1 70 < 1
2015 2015-08-11 1 70 < 1
2015 2015-08-11 1 70 < 1
2015 2015-02-11 1 70 < 1
2015 2015-02-10 1 70 < 1
2015 2015-02-10 1 70 < 1
2015 2015-02-10 1 70 < 1
2015 2015-02-10 1 70 < 1
2015 2015-02-09 1 70 < 1
2015 2015-02-09 1 70 < 1
2015 2015-02-09 1 70 < 1
2015 2015-02-09 1 70 < 1
molybdenum 1 40 2.45 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-12 1 40 2.3
2015 2015-08-12 1 40 2.2
2015 2015-08-12 1 40 < 1
2015 2015-08-12 1 40 5.1
2015 2015-08-11 1 40 2.7
2015 2015-08-11 1 40 < 1
2015 2015-08-11 1 40 1.2
2015 2015-08-11 1 40 3.7
2015 2015-08-11 1 40 3.4
2015 2015-02-11 1 40 1.1
2015 2015-02-10 1 40 3.5
2015 2015-02-10 1 40 4.4
2015 2015-02-10 1 40 1.2
2015 2015-02-10 1 40 5.3
2015 2015-02-09 1 40 2.4
2015 2015-02-09 1 40 3
2015 2015-02-09 1 40 < 1
2015 2015-02-09 1 40 2.6
strontium 0.3 1500 91.6 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-12 0.3 1500 16
2015 2015-08-12 0.3 1500 11
2015 2015-08-12 0.3 1500 160
2015 2015-08-12 0.3 1500 90
2015 2015-08-11 0.3 1500 96
2015 2015-08-11 0.3 1500 110
2015 2015-08-11 0.3 1500 100
2015 2015-08-11 0.3 1500 140
2015 2015-08-11 0.3 1500 99
2015 2015-02-11 0.3 1500 96
2015 2015-02-10 0.3 1500 130
2015 2015-02-10 0.3 1500 130
2015 2015-02-10 0.3 1500 140
2015 2015-02-10 0.3 1500 93
2015 2015-02-09 0.3 1500 18
2015 2015-02-09 0.3 1500 100
2015 2015-02-09 0.3 1500 110
2015 2015-02-09 0.3 1500 9.8
vanadium 0.2 21 < 0.2 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-12 0.2 21 < 0.2
2015 2015-08-12 0.2 21 < 0.2
2015 2015-08-12 0.2 21 < 0.2
2015 2015-08-12 0.2 21 < 0.2
2015 2015-08-11 0.2 21 < 0.2
2015 2015-08-11 0.2 21 < 0.2
2015 2015-08-11 0.2 21 < 0.2
2015 2015-08-11 0.2 21 < 0.2
2015 2015-08-11 0.2 21 < 0.2
2015 2015-02-11 0.2 21 < 0.2
2015 2015-02-10 0.2 21 < 0.2
2015 2015-02-10 0.2 21 < 0.2
2015 2015-02-10 0.2 21 < 0.2
2015 2015-02-10 0.2 21 < 0.2
2015 2015-02-09 0.2 21 < 0.2
2015 2015-02-09 0.2 21 < 0.2
2015 2015-02-09 0.2 21 < 0.2
2015 2015-02-09 0.2 21 < 0.2
1,1-dichloroethane 0.03 6.14 < 0.03 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-12 0.03 6.14 < 0.03
2015 2015-08-12 0.03 6.14 < 0.03
2015 2015-08-12 0.03 6.14 < 0.03
2015 2015-08-11 0.03 6.14 < 0.03
2015 2015-08-11 0.03 6.14 < 0.03
2015 2015-08-11 0.03 6.14 < 0.03
2015 2015-08-11 0.03 6.14 < 0.03
2015 2015-08-11 0.03 6.14 < 0.03
2015 2015-02-11 0.03 6.14 < 0.03
2015 2015-02-10 0.03 6.14 < 0.03
2015 2015-02-10 0.03 6.14 < 0.03
2015 2015-02-10 0.03 6.14 < 0.03
2015 2015-02-10 0.03 6.14 < 0.03
2015 2015-02-09 0.03 6.14 < 0.03
2015 2015-02-09 0.03 6.14 < 0.03
2015 2015-02-09 0.03 6.14 < 0.03
1,2,3-trichloropropane 0.03 0.0004 < 0.03 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-12 0.03 0.0004 < 0.03
2015 2015-08-12 0.03 0.0004 < 0.03
2015 2015-08-12 0.03 0.0004 < 0.03
2015 2015-08-11 0.03 0.0004 < 0.03
2015 2015-08-11 0.03 0.0004 < 0.03
2015 2015-08-11 0.03 0.0004 < 0.03
2015 2015-08-11 0.03 0.0004 < 0.03
2015 2015-08-11 0.03 0.0004 < 0.03
2015 2015-02-11 0.03 0.0004 < 0.03
2015 2015-02-10 0.03 0.0004 < 0.03
2015 2015-02-10 0.03 0.0004 < 0.03
2015 2015-02-10 0.03 0.0004 < 0.03
2015 2015-02-10 0.03 0.0004 < 0.03
2015 2015-02-09 0.03 0.0004 < 0.03
2015 2015-02-09 0.03 0.0004 < 0.03
2015 2015-02-09 0.03 0.0004 < 0.03
1,3-butadiene 0.1 0.0103 < 0.1 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-12 0.1 0.0103 < 0.1
2015 2015-08-12 0.1 0.0103 < 0.1
2015 2015-08-12 0.1 0.0103 < 0.1
2015 2015-08-11 0.1 0.0103 < 0.1
2015 2015-08-11 0.1 0.0103 < 0.1
2015 2015-08-11 0.1 0.0103 < 0.1
2015 2015-08-11 0.1 0.0103 < 0.1
2015 2015-08-11 0.1 0.0103 < 0.1
2015 2015-02-11 0.1 0.0103 < 0.1
2015 2015-02-10 0.1 0.0103 < 0.1
2015 2015-02-10 0.1 0.0103 < 0.1
2015 2015-02-10 0.1 0.0103 < 0.1
2015 2015-02-10 0.1 0.0103 < 0.1
2015 2015-02-09 0.1 0.0103 < 0.1
2015 2015-02-09 0.1 0.0103 < 0.1
2015 2015-02-09 0.1 0.0103 < 0.1
1,4-dioxane 0.07 0.35 < 0.07 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-12 0.07 0.35 < 0.07
2015 2015-08-12 0.07 0.35 < 0.07
2015 2015-08-12 0.07 0.35 < 0.07
2015 2015-08-11 0.07 0.35 < 0.07
2015 2015-08-11 0.07 0.35 < 0.07
2015 2015-08-11 0.07 0.35 < 0.07
2015 2015-08-11 0.07 0.35 < 0.07
2015 2015-08-11 0.07 0.35 < 0.07
2015 2015-02-11 0.07 0.35 < 0.07
2015 2015-02-10 0.07 0.35 < 0.07
2015 2015-02-10 0.07 0.35 < 0.07
2015 2015-02-10 0.07 0.35 < 0.07
2015 2015-02-10 0.07 0.35 < 0.07
2015 2015-02-09 0.07 0.35 < 0.07
2015 2015-02-09 0.07 0.35 < 0.07
2015 2015-02-09 0.07 0.35 < 0.07
bromomethane 0.2 140 < 0.2 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-12 0.2 140 < 0.2
2015 2015-08-12 0.2 140 < 0.2
2015 2015-08-12 0.2 140 < 0.2
2015 2015-08-11 0.2 140 < 0.2
2015 2015-08-11 0.2 140 < 0.2
2015 2015-08-11 0.2 140 < 0.2
2015 2015-08-11 0.2 140 < 0.2
2015 2015-08-11 0.2 140 < 0.2
2015 2015-02-11 0.2 140 < 0.2
2015 2015-02-10 0.2 140 < 0.2
2015 2015-02-10 0.2 140 < 0.2
2015 2015-02-10 0.2 140 < 0.2
2015 2015-02-10 0.2 140 < 0.2
2015 2015-02-09 0.2 140 < 0.2
2015 2015-02-09 0.2 140 < 0.2
2015 2015-02-09 0.2 140 < 0.2
chloromethane 0.2 2.69 < 0.2 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-12 0.2 2.69 < 0.2
2015 2015-08-12 0.2 2.69 < 0.2
2015 2015-08-12 0.2 2.69 < 0.2
2015 2015-08-11 0.2 2.69 < 0.2
2015 2015-08-11 0.2 2.69 < 0.2
2015 2015-08-11 0.2 2.69 < 0.2
2015 2015-08-11 0.2 2.69 < 0.2
2015 2015-08-11 0.2 2.69 < 0.2
2015 2015-02-11 0.2 2.69 < 0.2
2015 2015-02-10 0.2 2.69 < 0.2
2015 2015-02-10 0.2 2.69 < 0.2
2015 2015-02-10 0.2 2.69 < 0.2
2015 2015-02-10 0.2 2.69 < 0.2
2015 2015-02-09 0.2 2.69 < 0.2
2015 2015-02-09 0.2 2.69 < 0.2
2015 2015-02-09 0.2 2.69 < 0.2
Halon 1011 0.06 90 < 0.06 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-12 0.06 90 < 0.06
2015 2015-08-12 0.06 90 < 0.06
2015 2015-08-12 0.06 90 < 0.06
2015 2015-08-11 0.06 90 < 0.06
2015 2015-08-11 0.06 90 < 0.06
2015 2015-08-11 0.06 90 < 0.06
2015 2015-08-11 0.06 90 < 0.06
2015 2015-08-11 0.06 90 < 0.06
2015 2015-02-11 0.06 90 < 0.06
2015 2015-02-10 0.06 90 < 0.06
2015 2015-02-10 0.06 90 < 0.06
2015 2015-02-10 0.06 90 < 0.06
2015 2015-02-10 0.06 90 < 0.06
2015 2015-02-09 0.06 90 < 0.06
2015 2015-02-09 0.06 90 < 0.06
2015 2015-02-09 0.06 90 < 0.06
HCFC-22 0.08 0 < 0.08 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-12 0.08 0 < 0.08
2015 2015-08-12 0.08 0 < 0.08
2015 2015-08-12 0.08 0 < 0.08
2015 2015-08-11 0.08 0 < 0.08
2015 2015-08-11 0.08 0 < 0.08
2015 2015-08-11 0.08 0 < 0.08
2015 2015-08-11 0.08 0 < 0.08
2015 2015-08-11 0.08 0 < 0.08
2015 2015-02-11 0.08 0 < 0.08
2015 2015-02-10 0.08 0 < 0.08
2015 2015-02-10 0.08 0 < 0.08
2015 2015-02-10 0.08 0 < 0.08
2015 2015-02-10 0.08 0 < 0.08
2015 2015-02-09 0.08 0 < 0.08
2015 2015-02-09 0.08 0 < 0.08
2015 2015-02-09 0.08 0 < 0.08
PFBS 0.09 0 < 0.09 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-12 0.09 0 < 0.09
2015 2015-08-12 0.09 0 < 0.09
2015 2015-08-12 0.09 0 < 0.09
2015 2015-08-11 0.09 0 < 0.09
2015 2015-08-11 0.09 0 < 0.09
2015 2015-08-11 0.09 0 < 0.09
2015 2015-08-11 0.09 0 < 0.09
2015 2015-08-11 0.09 0 < 0.09
2015 2015-02-11 0.09 0 < 0.09
2015 2015-02-10 0.09 0 < 0.09
2015 2015-02-10 0.09 0 < 0.09
2015 2015-02-10 0.09 0 < 0.09
2015 2015-02-10 0.09 0 < 0.09
2015 2015-02-09 0.09 0 < 0.09
2015 2015-02-09 0.09 0 < 0.09
2015 2015-02-09 0.09 0 < 0.09
PFHpA 0.01 0 < 0.01 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-12 0.01 0 < 0.01
2015 2015-08-12 0.01 0 < 0.01
2015 2015-08-12 0.01 0 < 0.01
2015 2015-08-11 0.01 0 < 0.01
2015 2015-08-11 0.01 0 < 0.01
2015 2015-08-11 0.01 0 < 0.01
2015 2015-08-11 0.01 0 < 0.01
2015 2015-08-11 0.01 0 < 0.01
2015 2015-02-11 0.01 0 < 0.01
2015 2015-02-10 0.01 0 < 0.01
2015 2015-02-10 0.01 0 < 0.01
2015 2015-02-10 0.01 0 < 0.01
2015 2015-02-10 0.01 0 < 0.01
2015 2015-02-09 0.01 0 < 0.01
2015 2015-02-09 0.01 0 < 0.01
2015 2015-02-09 0.01 0 < 0.01
PFHxS 0.03 0 < 0.03 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-12 0.03 0 < 0.03
2015 2015-08-12 0.03 0 < 0.03
2015 2015-08-12 0.03 0 < 0.03
2015 2015-08-11 0.03 0 < 0.03
2015 2015-08-11 0.03 0 < 0.03
2015 2015-08-11 0.03 0 < 0.03
2015 2015-08-11 0.03 0 < 0.03
2015 2015-08-11 0.03 0 < 0.03
2015 2015-02-11 0.03 0 < 0.03
2015 2015-02-10 0.03 0 < 0.03
2015 2015-02-10 0.03 0 < 0.03
2015 2015-02-10 0.03 0 < 0.03
2015 2015-02-10 0.03 0 < 0.03
2015 2015-02-09 0.03 0 < 0.03
2015 2015-02-09 0.03 0 < 0.03
2015 2015-02-09 0.03 0 < 0.03
PFNA 0.02 0 < 0.02 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-12 0.02 0 < 0.02
2015 2015-08-12 0.02 0 < 0.02
2015 2015-08-12 0.02 0 < 0.02
2015 2015-08-11 0.02 0 < 0.02
2015 2015-08-11 0.02 0 < 0.02
2015 2015-08-11 0.02 0 < 0.02
2015 2015-08-11 0.02 0 < 0.02
2015 2015-08-11 0.02 0 < 0.02
2015 2015-02-11 0.02 0 < 0.02
2015 2015-02-10 0.02 0 < 0.02
2015 2015-02-10 0.02 0 < 0.02
2015 2015-02-10 0.02 0 < 0.02
2015 2015-02-10 0.02 0 < 0.02
2015 2015-02-09 0.02 0 < 0.02
2015 2015-02-09 0.02 0 < 0.02
2015 2015-02-09 0.02 0 < 0.02
PFOA 0.02 0.07 < 0.02 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-12 0.02 0.07 < 0.02
2015 2015-08-12 0.02 0.07 < 0.02
2015 2015-08-12 0.02 0.07 < 0.02
2015 2015-08-11 0.02 0.07 < 0.02
2015 2015-08-11 0.02 0.07 < 0.02
2015 2015-08-11 0.02 0.07 < 0.02
2015 2015-08-11 0.02 0.07 < 0.02
2015 2015-08-11 0.02 0.07 < 0.02
2015 2015-02-11 0.02 0.07 < 0.02
2015 2015-02-10 0.02 0.07 < 0.02
2015 2015-02-10 0.02 0.07 < 0.02
2015 2015-02-10 0.02 0.07 < 0.02
2015 2015-02-10 0.02 0.07 < 0.02
2015 2015-02-09 0.02 0.07 < 0.02
2015 2015-02-09 0.02 0.07 < 0.02
2015 2015-02-09 0.02 0.07 < 0.02
PFOS 0.04 0.07 < 0.04 [+] Expand Test Data
Year Test Date MRL HRL Test Result
2015 2015-08-12 0.04 0.07 < 0.04
2015 2015-08-12 0.04 0.07 < 0.04
2015 2015-08-12 0.04 0.07 < 0.04
2015 2015-08-11 0.04 0.07 < 0.04
2015 2015-08-11 0.04 0.07 < 0.04
2015 2015-08-11 0.04 0.07 < 0.04
2015 2015-08-11 0.04 0.07 < 0.04
2015 2015-08-11 0.04 0.07 < 0.04
2015 2015-02-11 0.04 0.07 < 0.04
2015 2015-02-10 0.04 0.07 < 0.04
2015 2015-02-10 0.04 0.07 < 0.04
2015 2015-02-10 0.04 0.07 < 0.04
2015 2015-02-10 0.04 0.07 < 0.04
2015 2015-02-09 0.04 0.07 < 0.04
2015 2015-02-09 0.04 0.07 < 0.04
2015 2015-02-09 0.04 0.07 < 0.04

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 level. Lead and copper can be — and often are — deposited in drinking water in between the water facility and your tap.

Sample ID Contaminant Sampling Start Date Sampling End Date Result
VA27144 lead 2016-01-01 2018-12-31 0mg/L
VA22720 lead 2013-01-01 2015-12-31 0.001mg/L
VA19249 lead 2010-01-01 2012-12-31 0.002mg/L
VA14657 lead 2009-01-01 2009-12-31 0.003mg/L

Violations


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

Compliance Dates Rule Violation Type Contaminant Name Status
- N/A Total Coliform Rule Maximum Contaminant Level Violation, Monthly (TCR) Coliform (TCR) Known
- N/A Total Coliform Rule Maximum Contaminant Level Violation, Monthly (TCR) Coliform (TCR) Known
- N/A Total Coliform Rule Maximum Contaminant Level Violation, Monthly (TCR) Coliform (TCR) Known
- N/A Total Coliform Rule Maximum Contaminant Level Violation, Monthly (TCR) Coliform (TCR) Known
- N/A Total Coliform Rule Maximum Contaminant Level Violation, Monthly (TCR) Coliform (TCR) Known
- N/A Total Coliform Rule Maximum Contaminant Level Violation, Monthly (TCR) Coliform (TCR) Known
- N/A Total Coliform Rule Monitoring, Routine Major (TCR) Coliform (TCR) Known
- N/A Total Coliform Rule Monitoring, Routine Major (TCR) Coliform (TCR) Known

Local Water Testing


Find a lab in your area so you can get your tap or well water tested. This list contains both governmental and private labs, all of which are EPA-certified for drinking water testing.

Lab Location Zip Code
ENVIRONMENTAL HAZARDS SERVICES LLC RICHMOND, VA 23237
Environmental Hazards Services LLC Richmond, VA 23237
Schneider Laboratories Global, Incorporated Richmond, VA 23220-5117

Water Bill Information


Convenient information about your water service.

Unable to identify any billing information about Jcsa - Central System (VA3095490).

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.