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MT Pleasant Waterworks

What EPA’s and South Carolina’s records show in this utility’s water: PFAS and lithium; nitrate, arsenic and other regulated chemicals; lead and copper; and violations since 2016, with the certification that handles each result.

Serves
91,500 people
Connections
44,803
Water source
Surface water bought from another system
Based in
Mount Pleasant, SC
County
Charleston
Owner
Local government
The 4 ZIP codes it serves

29429, 29464, 29465, 29466

The short answer

2 results are above EPA’s new limit, which takes effect in 2029, and 1 more is above the health goal. The worst: PFOS, above EPA’s new limit (2029). No health-based violations on file since 2016.

What handles it

What was found

PFAS and lithium: EPA UCMR 5, samples taken from Feb. 26, 2024 to Jan. 6, 2025.

Lead and copper: EPA SDWIS monitoring periods ending 2005 to 2026.

Haloacetic acids (HAA5), total trihalomethanes (TTHM), fluoride, nitrate, arsenic and chromium (total): South Carolina’s own results, samples taken from Jan. 7, 2020 to Sept. 8, 2026, with EPA’s 2012 to 2019 file for earlier years.

PFAS: PFOS, PFOA and PFBS were found, of the six PFAS in EPA’s 2024 drinking water rule; their results are below. Three other PFAS with no federal limit were found, the highest PFBA at 6.3 ppt: see them below.

EPA’s 2024 PFAS rule, compound by compound

PFASEPA’s limitResult
PFOA4.0 pptAbove EPA’s new limit (2029)5.5 ppt highest, found in 3 of 12 samples. Details
PFOS4.0 pptAbove EPA’s new limit (2029)8.4 ppt highest, found in 4 of 12 samples. Details
PFHxS10 pptNot foundNot found in any of 12 samples, below 3 ppt
PFNA10 pptNot foundNot found in any of 12 samples, below 4 ppt
HFPO-DA (GenX)10 pptNot foundNot found in any of 12 samples, below 5 ppt
PFBSIndex onlyBelow EPA’s limits4.4 ppt highest, found in 3 of 12 samples. Details
Hazard IndexPFHxS, PFNA, HFPO-DA and PFBS together1Doesn’t applyDoesn’t apply: no sampling location found two or more of the four
Results from EPA’s UCMR 5 sampling. “Below” is the lab’s reporting level: a result under it reads as not found, which is not the same as zero. The limits are EPA’s 2024 rule, with compliance due from 2029; EPA has since proposed changes to some of them, explained on each compound’s page. PFBS has no limit of its own and counts only toward the Hazard Index, which adds up the four, each against EPA’s health-based level, from each sampling location’s average, as EPA’s UCMR 5 summary does. It counts only where two or more of the four were found, and is above the limit from 1.5.

About PFAS certifications

NSF’s PFAS claims are tested to below 20 ppt. EPA’s limit is 4.0 ppt, and EPA says no certification yet shows a filter reaching its levels.

Above EPA’s new limit, which takes effect in 20292

PFOS

Comes from the source

Above EPA’s new limit (2029)

8.4ppt

Highest sample, Nov. 13, 2024; found in 4 of 12

The highest sample was 8.4 ppt, about twice EPA’s new limit of 4.0 ppt, which takes effect in 2029. EPA’s health goal is zero. Compliance will be judged on a running annual average, not one sample. Averaged by sampling location, as EPA compares its UCMR 5 results with the limit, the highest was 6.6 ppt, also above it.

What handles it

PFOA

Comes from the source

Above EPA’s new limit (2029)

5.5ppt

Highest sample, Nov. 13, 2024; found in 3 of 12

The highest sample was 5.5 ppt, above EPA’s new limit of 4.0 ppt, which takes effect in 2029. EPA’s health goal is zero. Compliance will be judged on a running annual average, not one sample. Averaged by sampling location, as EPA compares its UCMR 5 results with the limit, the highest was 3.6 ppt, below it.

What handles it

Above the health goal1

Lead

Comes from pipes, often your own

Above the health goal

1.0ppb

90th percentile, 2024 to 2026

In the latest period, 9 in 10 homes sampled were at or below 1.0 ppb, below EPA’s action level of 15 ppb. The action level drops to 10 ppb on Nov. 1, 2027. EPA’s health goal for lead is zero.

What handles it

Below EPA’s limits5

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

11.7ppb

Highest yearly average, 2020 to 2026

2026 average: 7.3 ppb

Averaged by year, the highest was 11.7 ppb, in 2023, below EPA’s legal limit of 60 ppb. Its highest single sample was 22.1 ppb. In 2026, the latest year on file, its 24 samples averaged 7.3 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 22.3 ppb, in 2015.

What handles it

No certification claim covers this compound yet.

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

10.0ppb

Highest yearly average, 2020 to 2026

2026 average: 6.8 ppb

Averaged by year, the highest was 10.0 ppb, in 2021, below EPA’s legal limit of 80 ppb. Its highest single sample was 22.5 ppb. In 2026, the latest year on file, its 24 samples averaged 6.8 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 14.2 ppb, in 2012.

What handles it

  • NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
  • NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.47ppm

Highest yearly average, 2022 to 2025

2025 average: 0.42 ppm

Averaged by year, the highest was 0.47 ppm, in 2022, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 0.64 ppm. In 2025, the latest year on file, its four samples averaged 0.42 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.54 ppm, in 2019.

What handles it

Nitrate

Comes from the source

Below EPA’s limits

0.082ppm

Highest sample; found in 5 of 28

2026: not found

The highest sample, in 2021, was 0.082 ppm, below EPA’s legal limit of 10 ppm. In 2026, the latest year on file, it wasn’t found in any of its four samples. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 0.57 ppm, in 2015.

What handles it

  • NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
  • NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”

PFBS

Comes from the source

Below EPA’s limits

4.4ppt

Highest sample, Feb. 26, 2024; found in 3 of 12

The highest sample was 4.4 ppt, below EPA’s hazard index benchmark of 2,000 ppt. PFBS has no legal limit or health goal of its own.

What handles it

South Carolina utilities above EPA’s PFAS limits

Also found, with no federal limit

EPA measured these PFAS to learn how often they occur. None has a legal limit or a health goal yet.

CompoundHighest sampleFound inCertification claim
PFBA6.3 ppt2 of 12None covers it
PFPeA6.0 ppt4 of 12None covers it
PFHxA5.1 ppt3 of 12None covers it
26 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.

From routine monitoring

  • Arsenic
  • Chromium (total)

PFAS and lithium, from EPA’s UCMR 5 sampling

  • 11Cl-PF3OUdS
  • 4:2 FTS
  • 6:2 FTS
  • 8:2 FTS
  • 9Cl-PF3ONS
  • ADONA
  • HFPO-DA (GenX)
  • Lithium
  • NEtFOSAA
  • NFDHA
  • NMeFOSAA
  • PFDA
  • PFDoA
  • PFEESA
  • PFHpA
  • PFHpS
  • PFHxS
  • PFMBA
  • PFMPA
  • PFNA
  • PFPeS
  • PFTA
  • PFTrDA
  • PFUnA

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

    Claims: PFOS Reduction, PFOA Reduction, Lead Reduction

    For: PFOS, PFOA, Lead

    Other certifiers’ wording: Total PFAS Reduction; Perfluorooctane Sulfonate (PFOS); Perfluorooctanoic Acid (PFOA)

  • NSF/ANSI 58

    Claims: Perfluorooctane Sulfonate (PFOS), Perfluorooctanoic Acid (PFOA), Lead Reduction

    For: PFOS, PFOA, Lead

At the tap, or for the whole house?

Lead and copper usually come from pipes and fixtures inside or near your home. A whole-house system sits where water enters, so it cannot catch what your own plumbing adds after it. For those, the filter that counts is the one at the tap. 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

Compare five-year costs

The best water filters for PFAS, ranked

The best water filters for lead, ranked

Disinfectant

MT Pleasant Waterworks reported adding chloramine before water enters its pipes, at all 5 of its sampling points, in its 2024 to 2025 sampling for EPA. It also reported chlorine dioxide.

Chloramine is chlorine combined with ammonia. It lasts longer in the pipes, and unlike chlorine, it doesn’t leave water that sits out. A filter’s chlorine claim doesn’t cover it: look for the separate chloramine claim under NSF/ANSI 42. No shower filter can carry one: NSF/ANSI 177, the shower filter standard, covers free chlorine only. Fish, turtles and frogs need it removed from their water. This utility buys its water from another system, so what it reported may leave out treatment done before the water reaches it. This is what the utility reported for that sampling. Its annual water quality report says what it uses now.

Chlorine vs. chloramineFilters with a chloramine claimShower filters, by what their listings cover

Violations since 2016

No health-based violations on file with EPA since 2016. There is 1 monitoring or reporting violation: a sample missed, late or not reported.

What this report can’t tell you

  • Everything else. Haloacetic acids (HAA5), total trihalomethanes (TTHM), fluoride, nitrate, arsenic and chromium (total) results here are South Carolina’s own from 2020 on, with EPA’s national file for 2012 to 2019. MT Pleasant Waterworks’s own annual report, which it must send you every year, has 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 samples are from Feb. 26, 2024 to Jan. 6, 2025; South Carolina’s results run from Jan. 7, 2020 to Sept. 8, 2026.

Testing your own tap

MT Pleasant Waterworks’s results are for the water it sends out. What your own service line, solder and fixtures add shows up only in a test of your tap, by a lab South Carolina certifies.

The 3 labs South Carolina certifies closest to the area MT Pleasant Waterworks serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • GEL Laboratories LLC

    Charleston, SC · about 16 miles

    Certified for nitrate, lead and copper, metals, minerals and other inorganics, PFAS, radioactivity

    (843) 556-8171

  • Trident Labs Services Inc.

    Ladson, SC · about 21 miles

    Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics

    (843) 871-4999

  • Aquatic Analytics LLC

    Summerville, SC · about 27 miles

    Certified for bacteria, nitrate, minerals and other inorganics

    (843) 471-1933

All 36 certified labs for South Carolina

Sources

PWSID SC1010002. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Also in Charleston County

All South Carolina utilities

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