State Well Water Guide
Rhode Island Private Well Water Guide
Rhode Island is the most densely populated state with a significant private well population — approximately 12% of residents, or about 125,000 people, rely on private wells. Most private well users are in Kent, Washington, and Providence counties. Rhode Island's geology includes granite bedrock in the northern third of the state and glacial outwash deposits across much of the state. Arsenic from granite is a documented concern, as is PFAS from Quonset State Airport and former naval activities at Naval Air Station Quonset Point. The RI DEM certifies labs and provides guidance under the Private Well Regulation Act.
Testing Guidance
Rhode Island DEM recommends annual testing for coliform bacteria. Test for arsenic and radon-in-water for all granite bedrock wells at initial testing and every 5 years. PFAS testing is recommended for wells within 2 miles of Quonset Airport, North Kingstown. Nitrate testing is warranted near septic systems on small lots, agricultural areas in South County, and near the former military operations areas in South Kingston.
What to Test For in Rhode Island
Total coliform bacteria and E. coli — annual minimum
Arsenic — granite bedrock wells in northern and western Rhode Island
Radon in water — granite terrain in Providence and Kent counties
PFAS — wells near Quonset Airport, North Kingstown, and former NAS Quonset Point
Nitrates — South County agricultural areas, dense septic areas
Lead — homes built before 1986 with older plumbing
Volatile organic compounds — wells near former industrial sites in Providence, Cranston, or Woonsocket
Manganese and iron — glacial outwash deposits can have elevated iron and manganese
Common Contamination Risks in Rhode Island
Arsenic from granite bedrock — northwestern Rhode Island has documented arsenic in bedrock wells above the EPA MCL; strongly tied to the Scituate Reservoir granite complex
PFAS from Quonset Point — former Naval Air Station Quonset Point and the current Quonset State Airport have documented PFAS in groundwater from AFFF firefighting foam use; private wells in North Kingstown are the most affected
Radon dissolved in water from granite — northern RI, especially Providence County, has elevated radon in bedrock groundwater
Industrial VOC contamination — Rhode Island's industrial heritage, particularly in Providence and Pawtucket, has left legacy VOC plumes affecting some private wells near former manufacturing sites
Coliform from shallow wells — Rhode Island's high development density means many older wells have inadequate separation from septic systems; bacteria contamination is a persistent risk
Nitrates from septic systems — Rhode Island's small lot sizes mean many wells have substandard setbacks from septic systems, creating nitrate contamination risk
Contaminant Guides Relevant to RI Wells
PFAS
Synthetic Chemicals
EPA limit: 4 ppt
Lead
Heavy Metals
EPA limit: 15 ppb (action level)
Nitrates
Agricultural Chemicals
EPA limit: 10 mg/L
DBPs
Disinfection Byproducts
EPA limit: 80 µg/L (TTHMs) / 60 µg/L (HAA5)
Arsenic
Heavy Metals
EPA limit: 10 ppb
Hard Water
Minerals
EPA limit: No federal limit
Chlorine
Disinfection Chemicals
EPA limit: 4 mg/L (MRDL)
Microplastics
Emerging Contaminants
EPA limit: No federal limit
Bacteria
Microbial Contamination
EPA limit: Zero E. coli / < 1 coliform per 100 mL
Fluoride
Minerals
EPA limit: 4 mg/L (MCL) / 2 mg/L (Secondary MCL)
Chromium-6
Heavy Metals
EPA limit: 100 ppb (total chromium)
Copper
Heavy Metals
EPA limit: 1.3 mg/L (action level)
Radon
Radioactive Contaminants
EPA limit: No finalized MCL
Iron & Manganese
Minerals
EPA limit: 0.3 mg/L iron / 0.05 mg/L manganese (aesthetic SMCLs)
Atrazine
Agricultural Chemicals
EPA limit: 3 ppb (0.003 mg/L)
Uranium
Radioactive Contaminants
EPA limit: 30 µg/L (30 ppb)
Perchlorate
Industrial Chemicals
EPA limit: 0.056 mg/L (56 ppb)
VOCs
Industrial Chemicals
EPA limit: Varies by compound: benzene 5 ppb; TCE 5 ppb; PCE 5 ppb; vinyl chloride 2 ppb
Radium
Radioactive Contaminants
EPA limit: 5 pCi/L (combined Ra-226 + Ra-228)
Crypto & Giardia
Microbial Contamination
EPA limit: Zero (treatment technique standard)
Hydrogen Sulfide
Naturally Occurring Compounds
EPA limit: No MCL; Secondary MCL (aesthetic) of 0.05 mg/L
Selenium
Minerals
EPA limit: 50 ppb (0.05 mg/L)
Cadmium
Heavy Metals
EPA limit: 5 ppb (0.005 mg/L)
Mercury
Heavy Metals
EPA limit: 2 ppb (0.002 mg/L)
Barium
Heavy Metals
EPA limit: 2 mg/L
Find a Certified Lab in Rhode Island
Use the Rhode Island state-certified laboratory program to find accredited labs for private well testing. Always verify current certification before submitting samples.
RI Certified Lab Directory ↗Rhode Island Well Water FAQs
Related Pages
Data Sources & Provenance
All data on this page is sourced from official U.S. government or public datasets.
Quick Reference
State program
RI Certified Labs ↗EPA guidance
EPA Private Wells Program ↗State lab directory
RI Certified Labs ↗Minimum Annual Tests
Plus state-specific contaminants listed above
Other State Guides