Well (C) Daniel Friedman Table of Drinking Water Contaminant Levels
What is the Maximum Contamination Allowed in Water?

  • WATER CONTAMINANT LEVELS - CONTENTS: Allowable limits of water contaminants in drinking water
    • What are the action levels for different contaminants found in drinking water?
    • New York State example of maximum level of water contaminants allowed
  • POST a QUESTION or READ FAQs about allowable 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.

Analyte 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)

More Reading

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Frequently Asked Questions (FAQs) about Well Water Quality & Water Contaminant Levels


Please help! I am stumped, how am i getting good readings at my well when im not adding any chlorine and still getting good readings through out all my mobile home rentals? - Smitty Smith 6/28/12



What kind of good readings at your well?

If you mean a bacteria test that is not showing any bacterial contamiantion, if the current water coming into your system is not contaminated with bacteria it won't show up, chlorine or not.


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