The Power of Information

National Drinking Water Database


Merrimack Valley Montessor Sch - Portsmouth, NH


Serves 65 people - Test data available: 2004-2008

This drinking water quality report shows results of tests conducted by the water utility and provided to the Environmental Working Group (EWG) by the New Hampshire Department of Environmental Services. It is part of EWG's national database that includes 47,667 drinking water utilities and 20 million test results. Water utilities nationwide detected more than 300 pollutants between 2004 and 2009. More than half of these chemicals are unregulated, legal in any amount. Despite this widespread contamination, the federal government invests few resources to protecting rivers, reservoirs, and groundwater from pollution in the first place. The information below summarizes test results for this utility and lists potential health concerns.

 
This Drinking Water System
National Average
Exceed Health GuidelinesTests showing chemicals at concentrations above health guidelines established by federal and state health agencies. These guidelines are typically set at a levels that pose no significant health risk.
2 chemicals
4
Health Standard ExceedencesChemicals detected at concentrations above the legal limit, the Maximum Contaminant Level (MCLs) established by the U.S. EPA. 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.
2 chemicals
0.5
Pollutants FoundThe total number of contaminants detected since 2004, according to data provided by the state water agency.
4 chemicals
8
Tests ConductedThe total number of number of water quality tests conducted by water utilities and recorded in data provided by the state water agency.
202 tests
420

Contaminants Exceeding Health Guidelines

ContaminantAverage/
Maximum
Result
Health Limit
Exceeded
Legal Limit
Exceeded

Testing History

-Tested      -Detected      -Over Health Guidelines      -Over Legal Limit*
Arsenic (total)Arsenic contaminates drinking water due to mining runoff, erosion of natural deposits, emissions from glass and electronics processing and the use of arsenical compounds as wood preservatives and pesticides.16.6 ppb
16.6 ppb
Yes
MCLGA 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.: 0 ppb
Yes
10 ppb
ManganeseManganese is a naturally occurring element released from mineral deposits as well as industrial use.156.6 ppb
156.6 ppb
Yes
50 ppb
Yes
50 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.

Other Detected Contaminants

ContaminantAverage/
Maximum
Result
Health Limit
Exceeded
Legal Limit
Exceeded

Testing History

-Tested      -Detected      -Over Health Guidelines      -Over Legal Limit*
Barium (total)Barium is a mineral that enters drinking water through drilling and mining waste runoff, discharges from chemical industries and erosion of natural deposits.7.3 ppb
7.3 ppb
No
700 ppb
No
2000 ppb
Mercury (total inorganic)Mercury is a metal from refinery and factory pollution, coal burning, landfill and agricultural runoff and erosion of natural deposits.0.9 ppb
0.9 ppb
No
1.2 ppb
No
2 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.

Contaminants Not Detected - 61 chemicals

1,1,1,2-Tetrachloroethane, 1,1,1-Trichloroethane, 1,1,2,2-Tetrachloroethane, 1,1,2-Trichloroethane, 1,1-Dichloroethane, 1,1-Dichloroethylene, 1,1-Dichloropropene, 1,2,3-Trichlorobenzene, 1,2,3-Trichloropropane, 1,2,4-Trichlorobenzene, 1,2,4-Trimethylbenzene, 1,2-Dichloroethane, 1,2-Dichloropropane, 1,3,5-Trimethylbenzene, 1,3-Dichloropropane, 1,3-Dichloropropene, 2,2-Dichloropropane, Benzene, Bromobenzene, Bromochloromethane, Bromodichloromethane, Bromoform, Bromomethane, Carbon tetrachloride, Chloroethane, Chloroform, Chloromethane, cis-1,2-Dichloroethylene, Dibromochloromethane, Dibromomethane, Dichlorodifluoromethane, Dichloromethane (methylene chloride), Ethylbenzene, Ethylene dibromide (EDB), Hexachlorobutadiene, Isopropylbenzene, m-Dichlorobenzene, Monochlorobenzene (Chlorobenzene), Mtbe, n-Butylbenzene, n-Propylbenzene, Naphthalene, Nitrate, Nitrite, o-Chlorotoluene, o-Dichlorobenzene, p-Chlorotoluene, p-Dichlorobenzene, p-Isopropyltoluene, p-Xylene, sec-Butylbenzene, Styrene, tert-Butylbenzene, Tetrachloroethylene, Toluene, Total trihalomethanes (TTHMs), trans-1,2-Dichloroethylene, Trichloroethylene, Trichlorofluoromethane, Vinyl chloride, Xylenes (total)

Pollution Summary

4Total Contaminants Detected (2004 - 2008)

Arsenic (total), Barium (total), Manganese, Mercury (total inorganic)

1Agricultural Pollutants
(pesticides, fertilizer, factory farms)

Arsenic (total)

2Sprawl and Urban Pollutants
(road runoff, lawn pesticides, human waste)

Arsenic (total), Mercury (total inorganic)

4Industrial Pollutants

Arsenic (total), Barium (total), Manganese, Mercury (total inorganic)

0Water Treatment and Distribution Byproducts
(pipes and fixtures, treatment chemicals and byproducts)

4Naturally Occurring
(naturally present but increased for lands denuded by sprawl, agriculture, or industrial development)

Arsenic (total), Barium (total), Manganese, Mercury (total inorganic)

EPA Violation Summary

Violation CategoryNumber of Violations
MCL and Treatment
(click see violations)
2
Reporting
(click see violations)
2

Information on violations is drawn directly from EPA's national violations database in the Agency's Safe Drinking Water Information System. Analyses by others have raised questions about the quality of the information in EPA's database. For the purposes of this investigation, EWG is not showing below or including in our analyses, those violations for individual water suppliers that occurred on days for which the total number of violations assigned by EPA to that water supplier was greater than 20. This criteria was based on common characteristics of incorrect violations data as identified by water utilities, from a review of EPA's violations data by several hundred utilities prior to the release of EWG's investigation.