Emerald Lake
What EPA’s and CDC’s records show in this utility’s water: nitrate, arsenic and other regulated chemicals, plus violations since 2016, with the certification that handles each result.
- Serves
- 1,300 people
- Connections
- 528
- Water source
- Groundwater
- Based in
- Hillsborough, NH
- County
- Hillsborough
- Owner
- Local government
The ZIP code it serves
The short answer
1 result is above EPA’s legal limit. The worst: Arsenic, above the legal limit. 5 health-based violations since 2016.
What handles itWhat was found
Arsenic, haloacetic acids (HAA5), total trihalomethanes (TTHM), nitrate and uranium: New Hampshire’s yearly averages per water system, as CDC’s Environmental Public Health Tracking Network publishes them, 2020 to 2023, with EPA’s 2012 to 2019 file for earlier years.
Fluoride and chromium (total): EPA’s compliance monitoring file, samples taken from Jan. 16, 2014 to Dec. 9, 2019. Newer results are in the utility’s annual water quality report.
Above the legal limit1
Arsenic
Comes from the source
3.9ppb
Highest yearly average, 2020 to 2023
2023 average: 2.8 ppb
Averaged by year, the highest was 3.9 ppb, in 2022: below EPA’s legal limit of 10 ppb, but above its health goal of zero. In 2023, the latest year on file, it averaged 2.8 ppb. EPA judges this limit at each sampling point, and recorded a violation for arsenic at this utility in 2020. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 9.9 ppb, in 2019, and EPA recorded a violation in 2019.
What handles it
- NSF/ANSI 58 look for “Arsenic (Pentavalent)<=50 ppb Reduction”
- NSF/ANSI 53 look for “Arsenic (Pentavalent)<=50 ppb Reduction”
Below EPA’s limits3
Fluoride
Forms or is added in treatment
3.6ppm
Highest yearly average, 2014 to 2019
2019 average: 2.7 ppm
Averaged by year, the highest was 3.6 ppm, in 2015, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 4.4 ppm. In 2019, the latest year on file, its six samples averaged 2.7 ppm. EPA recorded no violation for fluoride at this utility from 2012 to 2019.
What handles it
- NSF/ANSI 58 look for “Fluoride Reduction”
- NSF/ANSI 53 look for “Fluoride”
Haloacetic acids (HAA5)
Forms or is added in treatment
13.2ppb
Highest yearly average, 2020 to 2023
2023: not found
Averaged by year, the highest was 13.2 ppb, in 2020, below EPA’s legal limit of 60 ppb. In 2023, the latest year on file, it wasn’t found.
What handles it
No certification claim covers this compound yet.
Total trihalomethanes (TTHM)
Forms or is added in treatment
4.6ppb
Highest yearly average, 2020 to 2023
2023 average: 1.7 ppb
Averaged by year, the highest was 4.6 ppb, in 2020, below EPA’s legal limit of 80 ppb. In 2023, the latest year on file, it averaged 1.7 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 2.8 ppb, in 2019.
What handles it
- NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
- NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”
3 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
- Chromium (total)
- Nitrate
- Uranium
What handles it
A certification covers specific claims, not a whole standard. Look for these claims on the certifier’s listing, not the box. Wording varies a little: NSF writes “Lead Reduction,” WQA just “Lead.”
- NSF/ANSI 53
Claim: Arsenic (Pentavalent)<=50 ppb Reduction
For: Arsenic
Other certifiers’ wording: Arsenic (III) (50 ppb influent level)
- NSF/ANSI 58
Claim: Arsenic (Pentavalent)<=50 ppb Reduction
For: Arsenic
Other certifiers’ wording: Arsenic (Pentavalent)<=300 ppb Reduction; Arsenic (V) (300 ppb influent level)
At the tap, or for the whole house?
These come with the water itself, so a whole-house system certified for the same claims treats every tap and shower. A filter at the tap treats drinking water for much less. How whole-house systems compare.
Filters with those claims on a certifier’s listing
Disclosure: TapBuff earns a commission if you buy through some links on this page. It does not change which standard or filter we name. As an Amazon Associate, TapBuff earns from qualifying purchases. How TapBuff makes money
Countertop reverse osmosis
- IAPMO listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 4, 2026
Certified for: Arsenic
Aquasana SmartFlow Reverse Osmosis (AQ-SFRO2)
Under-sink reverse osmosis
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 9, 2026
Certified for: Arsenic
Brondell Capella RC250 Reverse Osmosis System
Under-sink reverse osmosis
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 9, 2026
Certified for: Arsenic
Violations since 2016
| Contaminant or rule | Type | Period | Measured | Status |
|---|---|---|---|---|
| Groundwater Rule | A significant problem found in a state inspection was not fixed on time.EPA: Failure To Address Deficiency | Oct. 2, 2020 | — | Unaddressed |
| Arsenic | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Jan. 1, 2020 to March 31, 2020 | 0.013 MG/L | Resolved |
| Arsenic | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Oct. 1, 2019 to Dec. 31, 2019 | 0.023 MG/L | Resolved |
| Arsenic | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | July 1, 2019 to Sept. 30, 2019 | 0.023 MG/L | Resolved |
| Arsenic | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | April 1, 2019 to June 30, 2019 | 0.015 MG/L | Resolved |
| Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 7 monitoring or reporting violations not shown. | ||||
What this report can’t tell you
Everything else. Arsenic, haloacetic acids (HAA5), total trihalomethanes (TTHM), nitrate and uranium results here are New Hampshire’s yearly averages as CDC publishes them, from 2020 on, with EPA’s national file for 2012 to 2019. Fluoride and chromium (total) come from EPA’s file alone, which ends in 2019. Emerald Lake’s own annual report, which it must send you every year, has newer results for those and the contaminants this page does not show.
Your own plumbing. Lead results are the 90th percentile across homes the utility samples. Your home’s service line, solder and fixtures decide yours. A certified lab test is the only way to know.
What it means for your health. This page reports what the records show and EPA’s limits and goals; it is not medical advice. If you are worried about a health effect, talk to a doctor or your local health department.
Anything after the latest data. SDWIS data is from 2026 Q3; UCMR 5 didn’t sample this utility; CDC’s yearly averages for New Hampshire cover 2020 to 2023; EPA’s compliance samples are from Jan. 16, 2014 to Dec. 9, 2019.
Testing your own tap
The 3 labs New Hampshire certifies closest to the area Emerald Lake serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
New Hampshire DHHS Public Health Laboratories
Concord, NH · about 18 miles
Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics, organic chemicals, disinfection byproducts, radioactivity
Eurofins Concord
Concord, NH · about 20 miles
Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics, organic chemicals, disinfection byproducts
Nelson Analytical Lab - Keene Division
Swanzey, NH · about 22 miles
Certified for bacteria
Sources
- EPA UCMR 5 occurrence data, file of Oct. 15, 2026
- EPA SDWA bulk download (SDWIS federal data), 2026 Q3
- CDC Environmental Public Health Tracking Network, yearly averages New Hampshire supplied to CDC, 2020 to 2023, read Oct. 8, 2026. TapBuff’s comparisons with EPA’s limits are its own, not CDC’s or New Hampshire’s.
- EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, file of Feb. 5, 2024
- Certified labs: New Hampshire ELAP, drinking water labs, as listed in TNI LAMS, read Oct. 13, 2026; distances from the Census 2020 ZIP code tabulation area gazetteer
- Limits and goals: each contaminant’s page, with its EPA source.
- How this page is built: methodology.
PWSID NH1141020. Rebuilt from EPA data on Oct. 18, 2026.
What to do next
- Read up on ArsenicWhat each one does to health, where it comes from, and the certification claim that addresses it.About Arsenic
- Get the utility’s own reportEmerald Lake must send you a water quality report every year. It covers contaminants this page does not show, and has newer results than EPA’s national file for the ones here that come from it.How to read it
- Test your own tap for leadYour service line, solder and fixtures decide the lead at your faucet, not the utility’s average.Lead in your water: what to do
- Compare certified filtersWhat the filters certified for these results cost over five years, cartridges included.Compare five-year costs