How do I check my sample results?

How do I know what my results mean?

Visit the NH DES Be Well Informed guide (even if you live in Maine!) to see what your results mean. When you enter your analytes, make sure you change the units to ug/L, which is how your results come back to you (the following units are equal: 10 ppb = 0.01 ppm = 0.01 mg/l = 10 ug/l).

What are the Maximum Contaminate Levels (MCLs) for each analyte?

The numbers below are standards set by the EPA for the maximum contaminant amount allowed in drinking water. These are set to protect public health. There are a few exceptions to the Maximum Contaminant Levels.

ContaminantSymbolEPA Maximum Contaminant Level
BerylliumBe4 ug/L
ChromiumCr100 ug/L
ManganeseMn50 ug/L**
IronFe300 ug/L**
NickelNiN/A
CopperCu1300 ug/L*
ArsenicAs10 ug/L
SeleniumSe50 ug/L
CadmiumCd5 ug/L
AntimonySb6 ug/L
BariumBa2000 ug/L
ThalliumTl2 ug/L
LeadPb15 ug/L
UraniumU30 ug/L
  • *Lead and Copper are regulated under an action level because they enter drinking water primarily through plumbing materials. Treatment at the tap is recommended.
  • **Iron and Manganese are “secondary standards” and not health threatening. The EPA sets these standards because contaminants present in your water above these standards, may cause your water to be discolored, taste funny, or have an odor. However, your water is still safe to drink.
  1. What is the EPA limit for the amount of arsenic allowable in public drinking water?

    The EPA limit for arsenic in public drinking water is 10 parts per billion (ppb), which is the same as 10 ug/L. This standard was adopted in 2001, replacing the old standard of 50 ppb. Public water systems were required to meet the new standard by 2006. 

  2.  Is drinking water containing less than 10 ug/L of arsenic safe to drink?

    No. The EPA’s goal is zero arsenic in drinking water. There isn’t really a “safe” level of arsenic because even low levels of arsenic may increase your risk of diseases like cancer, heart disease, and diabetes later in life. 

  3.  Is it important to get your well tested for arsenic and other contaminants?

    Yes. Bacteria, nitrates, arsenic, radon, uranium, lead, and copper are all important to test for. Watch this short video about concerns contaminants in drinking water can cause. 

  4. What should I do if I get a high test result?

    If anything is above the recommended federal guidelines, a confirmation sample should be collected before making any decisions regarding water treatment. It is a good idea to switch to drinking bottled water until you confirm the first test, and then install a remediation system if necessary. There are a number of certified water quality testing labs you can use (Maine labs and New Hampshire labs). 

  5.  Why do I have to retest my drinking water for arsenic every 3-5 years?

    Water quality can change over time due to natural and human-induced causes, so it’s important to monitor your well water. 

  6.  Why are there so many units associate with drinking water limits?

    The following units are equal: 10 ppb = 0.01 ppm = 0.01 mg/l = 10 ug/l

  7. Where should I go for well water advice? 
    Maine: 866-292-3474 or wellwater.maine.gov
    New Hampshire: 603-271-2513

More questions and answers:   https://www.dartmouth.edu/~toxmetal/arsenic/facts-on-arsenic.html