Well water in Chelmsford, Massachusetts

In Chelmsford, 3% of 64 tested well samples exceeded the EPA limit for nitrate (10 mg/L), based on public data from USGS Water Quality Portal.

918 test results across 15 contaminants from at least 45 wells, 1954 to 2019; chloride has the most at 262. Data refreshed September 3, 2026.

Compiled by Nick at Well Water Nerd from public records. How these pages are built

What individual samples found

Each row summarizes every public sample for that contaminant inside Chelmsford. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.

Contaminant	Above limit	Samples	Detected	Median	Highest	Limit
Nitrate 1954 to 2019	3%	64	100%	3.3	28	10 mg/L EPA limit
Fluoride 1954 to 2019	0%	56	98%	0.1	0.3	4 mg/L EPA limit
Chloride 1954 to 2019	no limit	262	100%	67	1,300	250 mg/L nuisance level
Sodium 1954 to 2019	no limit	240	100%	32.5	740	20 mg/L health guideline
Iron 1954 to 2019	no limit	199	92%	100	8,000	300 ug/L nuisance level
Manganese 1955 to 2019	no limit	76	88%	50	1,300	300 ug/L health guideline

Sampled fewer than 10 times, too few to summarize: PFOA (1), PFOS (1), E. coli (2), Radium (226 + 228) (4), Arsenic (3), Copper (3), Uranium (3), Lead (3), Radon (1).

Closer than the town

See the sampled wells near your address

The same records, drawn around one point: which wells within a few miles were sampled and what they found, how deep the wells next to you were drilled, and any leaking tank or cleanup site within a mile.

Check my address

What this means

The contaminants most often above their limit here are nitrate (3% of 64 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.

Chloride, Iron, and Manganese are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.

What to test for in Chelmsford

1
Nitrate
3% of 64 local samples were above the limit.
2
Radon
Median local reading is 990 pCi/L.
3
PFOA
Above the limit in 1 of 1 local samples; too few to quote a rate.
4
PFOS
Above the limit in 1 of 1 local samples; too few to quote a rate.
5
E. coli
Above the limit in 1 of 2 local samples; too few to quote a rate.
6
Copper
Detected in 100% of local samples.
7
Chloride
Detected in 100% of local samples.
8
PFAS
2 unlined landfills on record locally.
9
Volatile organic compounds (VOCs)
2 unlined landfills on record locally.

Test your Chelmsford well for nitrate, radon and PFOA

Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.

Order the Tap Score well water test kit, from $209 Already tested? Upload the report

Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.

Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.

Affiliate links: the merchant pays us a commission and the price is the same for you. It does not change what the data above says. As an Amazon Associate we earn from qualifying purchases.

Where to get a well tested in Massachusetts: certified labs, state programs and prices.

Already have results back? Get your lab report read against the Chelmsford numbers, $29. Every line explained, ranked by what matters, with the fix for each.

Wells in Chelmsford

62 domestic wells in Chelmsford are on record with the state since 1915. 96% are drilled into bedrock, and the typical well is 284 feet deep (one in ten goes past 496 feet).

In a typical Chelmsford well, bedrock starts about 27 feet down, the median yield is 15 gallons per minute, 2% of wells yield under 3 gallons per minute and usually need a storage tank.

Bedrock wells are where arsenic, uranium and radon come from: the water sits in fractures in granite and metamorphic rock and picks up whatever the rock carries. That is why testing for those three matters more here than in a dug or gravel well.

1960s

1970s

1980s

1990s

2000s

2010s

Find your own well's report

The state keeps the driller's report for most wells drilled since 1984. It tells you how deep your well is, where bedrock starts, and how much water it makes, which decides what treatment can work.

Open MassDEP Well Location Viewer and choose Water Well.
The completion report lists total depth, depth to bedrock, static water level, yield and the driller.

Drillers have filed completion reports with the state since 1984; the viewer's public copy is refreshed a few times a year.

The rock under Chelmsford

Not a principal aquifer

The USGS map places this area outside any principal aquifer, which usually means wells here draw from fractured bedrock or thin local deposits rather than a large regional aquifer. Bedrock wells of that kind are where arsenic, radon and uranium turn up, and yields vary from well to well.

Classification from the USGS Principal Aquifers of the United States (national map, 2003 edition, GIS release 2015), read at the town centroid. A single well can sit in a different unit, especially near a boundary.

Official help in Massachusetts

Two places to start that are not selling anything: the state program that answers private well questions, and its list of labs certified to run drinking water tests. A certified lab is the difference between a result you can act on and a number.

Private Wells, MassDEP
Certified Laboratories, MassDEP

Contamination sources on record in Chelmsford

MassDEP records 2 unlined landfills in Chelmsford, among 25 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.

2: unlined landfillsOlder unlined landfills are a leading source of PFAS, VOCs and metals in nearby wells.
20: registered underground storage tank sitesRegistered tanks are regulated and inspected; they matter most when they are old or near a shallow well.
3: other remediation projects

Treatment that fits the local profile

Nitrate

Point-of-use reverse osmosis; Anion exchange; Distillation

Chloride

Point-of-use reverse osmosis; Distillation

Iron

Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration

Manganese

Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis

Systems we would look at first

Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.

For nitrate

Under-sink reverse osmosis system

under-sink or countertop, about $300

Look for NSF/ANSI 58 certification listing the contaminant you need removed.

For nitrate

Aquasana SmartFlow reverse osmosis

under-sink or countertop, about $225

Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.

For iron

Iron and manganese oxidizing filter

whole-house, at the point of entry, about $1,800

Air-injection or greensand media; fixes staining at the source.

Free, no obligation

Get on the list for a free in-home water test in Chelmsford

No water treatment company serves Chelmsford through Well Water Nerd yet. We are signing licensed companies on county by county: they test at your tap for free, walk you through the numbers, and quote treatment only if something needs fixing. Leave your details and you are first in line. Nothing is shared until a company joins for Chelmsford, and you get an email naming it first.

Common questions

How deep are wells in Chelmsford?

The typical domestic well in Chelmsford is 284 feet deep, based on 62 wells reported to the state since 1915. One in ten is deeper than 496 feet. 96% are drilled into bedrock.

How often should I test a private well in Chelmsford?

Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.

Towns near Chelmsford

Closest first. Groundwater does not stop at a line on a map, so the next town over is a fair second opinion.

Want the numbers themselves? Download the Massachusetts dataset as CSV, every county and town, with the sources named.

Sources

USGS Water Quality Portal: 918 samples in Chelmsford. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
MassDEP well completion reports: 521 well records in Chelmsford, 62 domestic. Well completion reports filed with the Massachusetts Department of Environmental Protection, as published in the Well Location Viewer (April 2023 vintage). Only aggregates are shown; owner names and addresses are never stored. Retrieved September 16, 2026.
MassDEP regulated sites: 25 regulated sites located in Chelmsford. Chapter 21E release sites, solid waste landfills and underground storage tank facilities from the Massachusetts Department of Environmental Protection, through MassGIS. Retrieved September 16, 2026.

Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.