Individual Water Supply Wells - Fact Sheet #3

"Recommended Residential Water Quality Testing" is available in English and Spanish PDF.

Recommended Residential Water Quality Testing

Water quality testing is important for new drinking water wells in addition to periodic evaluation of existing wells. The table below lists the recommended testing parameters for new individual residential water supply wells. These tests should be performed following proper well installation and development, and prior to homeowner use. Beyond these initial tests it is recommended to test for coliform bacteria every year and to periodically re-test water quality for other well-specific constituents of concern.

All samples should be analyzed by a laboratory certified by the NYSDOH Environmental Laboratory Approval Program (ELAP) for testing potable water. A current listing of ELAP laboratories may be accessed at or by contacting your Local Health Department (LHD).

Analysis Recommended MCL(1)(2) Concerns
Arsenic (3) 0.01 mg/l Cancer of the skin, bladder, lungs, kidneys and liver
Chloride 250 mg/l Salty taste
Coliform Bacteria Any positive result Indicator of possible disease causing contamination, e.g. Gastro-intestinal illness
Lead 0.015 mg/l Brain, nerve and kidney damage (especially in children)
Nitrate 10 mg/l as N Methemoglobinemia ("blue baby syndrome")
Nitrite 1 mg/l as N Methemoglobinemia ("blue baby syndrome")
Iron 0.3 mg/l Rust-colored staining of fixtures or clothes
Manganese 0.3 mg/l Black staining of fixtures or clothes; potential nervous system damage
Iron plus manganese 0.5 mg/l Rusty or black staining of fixtures or clothes
Turbidity 5 NTU Cloudy, "piggybacking" of contaminants, interferes with chlorine and UV-light disinfection
Sulfate 250 mg/l Laxative effect
pH No designated limit Pipe corrosion (lead and copper), metallic-bitter taste
Hardness No designated limit Mineral and soap deposits, detergents are less effective
Alkalinity No designated limit Inhibits chlorine effectiveness, metallic-bitter taste
Sodium No designated limit(4) Effects on individuals with high blood pressure
  1. MCL means maximum contaminant level. The MCLs listed are based upon requirements for Public Water Supply systems and are also recommended for use on individual residential systems.
  2. mg/l means milligram per liter (parts per million); NTU means Nephelometric Turbidity Units.
  3. Contact your Local Health Department to determine if arsenic has been detected in local groundwater.
  4. Water containing more than 20 mg/l of sodium should not be used for drinking by people on severely restricted sodium diets. Water containing more than 270 mg/l of sodium should not be used by people on moderately restricted sodium diets.

Additional tests are recommended for naturally occurring constituents that appear on a regional basis such as: barium, fluoride, methane, radium, radon, and uranium. Additional tests may also be appropriate for contaminants associated with potential sources such as: oil storage facilities, junkyards, gasoline stations, landfills, industry, and active or historic agricultural use. Water samples from older existing residences or residences with corrosive water (i.e., pH less than 6.5) should be tested for lead and copper. In addition, you may wish to contact your LHD to check if any emerging contaminants have been detected in your area.

Some LHDs may have their own residential water quality testing requirements. Contact the LHD to determine their required analyses and procedures, and to inquire about any local water quality concerns.

The table below is based upon the United States Environmental Protection Agency's (USEPA) publication: "Drinking Water From Household Wells", January 2002, and may be used as a reference for determining additional testing.

Conditions or Nearby Activities: Test for:
Recurring gastro-intestinal illness1 Coliform bacteria, e-coli
Household plumbing contains lead (older homes) pH, lead, copper
Radon in indoor air or region is radon rich Radon
Corrosion of pipes, plumbing pH, lead, copper
Nearby areas of intensive agriculture Nitrate, pesticides, arsenic, coliform bacteria
Coal or other mining operations nearby Metals, pH, total dissolved solids
Gas drilling operations nearby Sodium, chloride, barium, strontium
Dump, junkyard, landfill, factory, gas station, or dry-cleaning operation nearby Volatile organic compounds, total dissolved solids, pH, sulfate, chloride, metals
Odor of gasoline or fuel oil, and near gas station or buried fuel tanks Volatile organic compounds
Objectionable taste or smell Hydrogen sulfide, pH, metals
Stained plumbing fixtures, toilet tanks or laundry Iron, copper, manganese, hardness
Salty taste and seawater, or a heavily salted roadway nearby Sodium, chloride, total dissolved solids
Scaly residues, soaps don't lather Hardness, chloride, sodium
Rapid wear of water treatment equipment pH, iron, manganese, hardness
Water softener needed to treat hardness Hardness, manganese, iron
Water appears cloudy, frothy, or colored Color, detergents, turbidity, total dissolved solids
Reddish-brown films on fixtures or toilet tanks Iron bacteria, iron, manganese

1 Individuals with symptoms of gastro-intestinal illness should seek the attention of a medical physician.

Sampling and Treatment
  1. Sampling for lead and coliform may give false results if sampling is not done properly. Please contact your Local Health Department for guidance on sampling and interpreting results.
  2. If testing shows any level above the recommended MCL, a new water source and/or treatment may be necessary. Please contact your Local Health Department for guidance.

Other sources of information that may be helpful:

For questions concerning this Fact Sheet or a copy of Appendix 5-B: contact