Well (C) Daniel FriedmanTable of Drinking Water Contaminant Levels
What Are the Maximum Acceptable Levels of Contaminants in Drinking Water?

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Limits of allowable levels of water contaminants:

When testing drinking water the contaminant limits listed here assist in deciding when water purification or other water treatment is needed.

This table provides the allowable limits of various contaminants found in drinking water.

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Table of Allowable Limits of Water Contaminants

While the table of water contamination ingredients and allowable levels is from New York State, these limits or similar numbers will apply in most jurisdictions. Water contamination limits and testing requirements in the U.S. are regulated by the Federal Clean Drinking Water act.

Subpart 5-1 of the New York State Sanitary Code defines "Maximum Water Contaminant Level' as the permissible level of a contaminant in water which is delivered to any user of a public water system. New York State does not regulate private drinking water supplies (single family homes on well water).

Most lenders require at least a confirmation of "potable" water meaning that bacteria count and coliform bacteria count is less than 1 CFU per 100 ml. of drinking water in the water test sample. Some lenders require water passing the FHA "Short" or FHA "Long" test list items. Readers of this article should also see Drinking Water Supply, Contamination Levels, Water Testing Procedures.


Table of Acceptable Limits on Common Drinking Water Contaminants

Analyte / Contaminant MCL(a) Unit
Arsenic 0.05 mg/L
Barium 2.00 mg/L
Cadmium 0.005 mg/L
Chloride 250.0 mg/L
Chromium 0.10 mg/L
Color 15 Pt Co units(d)
Copper Action Level=1.3(g) mg/L
Fluoride 2.2 mg/L
Iron 0.3(b) mg/L
Lead Action Level=0.015(g)(h) mg/L
Manganese 0.3 (b) mg/L
Mercury 0.002 mg/L
Nitrate-nitrogen 10 (f)(h) mg/L
Nitrite-nitrogen 1 (f)(h) mg/L
Odor 3 TON (e)
Selenium 0.01 mg/L
Silver 0.05 mg/L
Sodium designated limits (c) mg/L
Sulfate 250.0 mg/L




Coliform Bacteria <1 (h) Colony /100 ml
Total Bacteria <1 (h) Colony /100 ml

Notes about drinking water contaminant acceptable levels

(a) mg/L = milligrams per liter

(b) If iron and manganese are present, the total concentration of both should not exceed 0.5 mg/L.

© Water containing more than 20 mg/L of sodium should not be used for drinking by people of severely restricted sodium diets. Water containing more than 270 mg/L of sodium should not be used for drinking by people on moderately restricted sodium diets.

(d) Color test result expressed as Platinum Cobalt Color Units

(e) Odor test result expressed as Threshold Odor Number

(f) If nitrate and nitrite are present, the total concentration of both should not exceed 10 mg/L.

(g) "Action level" is the concentration of lead or copper (in a sample of water drawn from a tap normally used for drinking after a 6-hour period of no water use) that, when exceeded, triggers actions to be taken by a water system.

(h) FHA "Short List" items

(i) FHA "Long List" items - (indications to be added after lab review)


Continue reading at WELL WATER CONTAMINATION: CAUSES, CURES or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see BUILDING CODE DOWNLOADS - free downloadable PDF files of building codes & standards




Watch out: also see WATER TESTING ADVICE for home buyers and building owners: water contaminants, water test procedures, well shock procedures, preventing drinking water contamination, and CHEATING ON WATER TESTS that warns about how people accidentally or on purpose can obtain incorrect water test results.

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WATER CONTAMINANT LEVELS & LIMITS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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