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Public water system record

Gwa Central Water System

Serves an area of Guam, GU that includes Agana Heights, Piti, Asan and 11 more places · 21,398 people served

Federal records show 1 health-based violation and no monitoring/reporting issues for Gwa Central Water System in the last ten years. The most serious issue in this window was a resolved Revised Total Coliform Rule violation.

  • GU0000003
  • MANGILAO
  • GU
  • 21,398 served

System profile

Source water Purchased surface water
ZIP 96913
EPA system ID GU0000003

Verify this system on EPA ECHO →

Health-based violations, last 10 years
1
Resolved
1
Unresolved
0
Any acute record
Yes
Monitoring issues, last 10 years
0

Key facts

  • Gwa Central Water System draws water from 1 spring.
  • Most recent enforcement action: boil water order by Guam, April 2022.
  • Record on file since 1979, with 16 health-based violations before October 19, 2016.
  • Lead pipe inventory: 0 lead and 2,658 unknown out of 2,919 service lines.

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Health-based violations

Since October 2016

Violation data reflects EPA records through March 2026. For the most current status, visit the EPA ECHO database.

Contaminant Rule family Start date Status Acute
Revised Total Coliform Rule
Contaminant limit exceeded
 110 Apr 1, 2022 Resolved Yes

Full record since 1979

EPA's records for Gwa Central Water System go back to 1979. Before October 19, 2016 they list 16 health-based violations (14 resolved, 2 archived by EPA without a recorded fix) and 22 monitoring or reporting violations.

Violations that began in Health-based Monitoring and reporting
1970s 0 2
1980s 0 1
1990s 0 1
2000s 1 0
2010 to October 18, 2016 15 18
2020s 1 0

Most recent health-based violation before October 19, 2016: Haloacetic Acids (HAA5), began January 2012, Resolved.

Show all 16 health-based violations before October 19, 2016
Contaminant Start date Status
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.072 mg/L, federal limit 0.06 mg/L (1.2 times the limit)
 Jan 1, 2012 Resolved
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.148 mg/L, federal limit 0.08 mg/L (1.9 times the limit)
 Jan 1, 2012 Resolved
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.068 mg/L, federal limit 0.06 mg/L (1.1 times the limit)
 Oct 1, 2011 Resolved
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.145 mg/L, federal limit 0.08 mg/L (1.8 times the limit)
 Oct 1, 2011 Resolved
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.07 mg/L, federal limit 0.06 mg/L (1.2 times the limit)
 Jul 1, 2011 Resolved
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.139 mg/L, federal limit 0.08 mg/L (1.7 times the limit)
 Jul 1, 2011 Resolved
Total Coliform (acute)
Contaminant limit exceeded
 Jul 1, 2011 Archived
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.121 mg/L, federal limit 0.08 mg/L (1.5 times the limit)
 Apr 1, 2011 Resolved
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.104 mg/L, federal limit 0.08 mg/L (1.3 times the limit)
 Jan 1, 2011 Resolved
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.093 mg/L, federal limit 0.08 mg/L (1.2 times the limit)
 Oct 1, 2010 Resolved
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.098 mg/L, federal limit 0.08 mg/L (1.2 times the limit)
 Jul 1, 2010 Resolved
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.063 mg/L, federal limit 0.06 mg/L (1.1 times the limit)
 Apr 1, 2010 Resolved
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.104 mg/L, federal limit 0.08 mg/L (1.3 times the limit)
 Apr 1, 2010 Resolved
Haloacetic Acids (HAA5)
Contaminant limit exceeded
Measured 0.064 mg/L, federal limit 0.06 mg/L (1.1 times the limit)
 Jan 1, 2010 Resolved
Total Trihalomethanes (TTHMs)
Contaminant limit exceeded
Measured 0.109 mg/L, federal limit 0.08 mg/L (1.4 times the limit)
 Jan 1, 2010 Resolved
Total Coliform (acute)
Contaminant limit exceeded
 Jan 1, 2004 Archived

Enforcement actions

Guam regulators issued 3 boil water orders to Gwa Central Water System between 2004 and 2022. The most recent was a boil water order in April 2022.

Date By Action Violations covered
Apr 28, 2022 Guam Boil water order 1 violation (1 health-based): Revised Total Coliform Rule
Oct 3, 2013 Guam Boil water order 1 violation (1 health-based): Total Coliform
Jan 29, 2004 Guam Boil water order 1 violation (1 health-based): Total Coliform

What the violations mean

Revised Total Coliform Rule

1 incident

The system did not meet a requirement of the Revised Total Coliform Rule

Coliform and E. coli rules protect against bacteria in the distribution system

Where the water comes from

Gwa Central Water System draws water from 1 spring. It also buys water from U.S. Navy Water System. 1 other community water system buys water from Gwa Central Water System.

Buys water from

Community systems that buy water from it

Annual water quality report

Gwa Central Water System must give its customers an annual water quality report (Consumer Confidence Report) by July 1, with the levels its tests found in the previous year.

Systems serving 10,000 or more people must mail or deliver the report to every customer, and from 2027 they must send it twice a year.

Find a posted report with EPA's Consumer Confidence Report search

Testing your own water

To test the water at your tap, or a private well this record does not cover, use a laboratory certified for drinking water by Guam.

Certified drinking water labs by state EPA guidance for private wells