Short answer: In the 2024–2025 records we hold for Horsham, three PFAS, PFHxS, PFOA and PFOS, each had a sample above a 2024 EPA limit (not a violation: the limits are judged on a yearly average, due 2029), and a health-based violation is on record (EPA SDWIS). Also worth knowing: lithium sits above a screening level. 9 substances were detected and 22 were tested and not detected. The water is from Horsham Water&sewer Authority, serving 26,000 residents.
Three PFAS, PFHxS, PFOA and PFOS, each had a sample above a 2024 EPA limit (not a violation: the limits are judged on a yearly average, due 2029); lithium sits above a screening level.
What we found
9 detected results, by distance from their limit
Each bar runs to the named reference; the tick marks it. Open a row for five layers: measured, compared, meaning, where it matters, what to do.
PFOSPerfluorooctanesulfonic acid (PFOS)Above EPA's 2024 limit (one sample) · Federal MCL4.0 ng/L federal MCL (2024)33.8ng/L▾
① · Measured
33.8 ng/L, sampled 2024-02-20 to 2025-08-18. EPA UCMR 5.
② · Compared
4.0 ng/L federal MCL (2024): a legal limit. That limit is judged on a yearly average, and water systems have until 2029 to meet it, so a single sample is not a violation. EPA health goal (MCLG): 0.
③ · Meaning
One EPA sample measured 33.8 ng/L, above the 4 ng/L limit EPA set in 2024. That limit is judged on a yearly average, and water systems have until 2029 to meet it, so a single sample is not a violation.
④ · Where it matters
Comes with the source water; home plumbing does not add it.
⑤ · What to do
Test your own tap first. To reduce it: Reverse osmosis, or carbon certified for PFAS (NSF/ANSI 53 or 58 (PFOA/PFOS)).
PFOAPerfluorooctanoic acid (PFOA)Above EPA's 2024 limit (one sample) · Federal MCL4.0 ng/L federal MCL (2024)17.5ng/L▾
① · Measured
17.5 ng/L, sampled 2024-02-20 to 2025-08-18. EPA UCMR 5.
② · Compared
4.0 ng/L federal MCL (2024): a legal limit. That limit is judged on a yearly average, and water systems have until 2029 to meet it, so a single sample is not a violation. EPA health goal (MCLG): 0.
③ · Meaning
One EPA sample measured 17.5 ng/L, above the 4 ng/L limit EPA set in 2024. That limit is judged on a yearly average, and water systems have until 2029 to meet it, so a single sample is not a violation.
④ · Where it matters
Comes with the source water; home plumbing does not add it.
⑤ · What to do
Test your own tap first. To reduce it: Reverse osmosis, or carbon certified for PFAS (NSF/ANSI 53 or 58 (PFOA/PFOS)).
PFHxSPerfluorohexanesulfonic acid (PFHxS)Above EPA's 2024 limit (one sample) · Federal MCL10 ng/L federal MCL (2024)10.6ng/L▾
① · Measured
10.6 ng/L, sampled 2024-02-20 to 2025-08-18. EPA UCMR 5.
② · Compared
10 ng/L federal MCL (2024): a legal limit. That limit is judged on a yearly average, and water systems have until 2029 to meet it, so a single sample is not a violation.
③ · Meaning
One EPA sample measured 10.6 ng/L, above the 10 ng/L limit EPA set in 2024. That limit is judged on a yearly average, and water systems have until 2029 to meet it, so a single sample is not a violation.
④ · Where it matters
Comes with the source water; home plumbing does not add it.
⑤ · What to do
Test your own tap first. To reduce it: Reverse osmosis, or carbon certified for PFAS (NSF/ANSI 53 or 58, with PFHxS named on the listing).
HORSHAM WATER&SEWER AUTHORITY (EPA PWSID PA1460033) delivers surface water to 26,000 residents. This report reflects 29 individual PFAS result(s) from the source UCMR5 observations and the latest Lead & Copper Rule 90th-percentile result. Water hardness and disinfectant type are pending the utility's own annual report.
Track record
1health-based violation in the last 10 years
From EPA SDWIS. Counted once per contaminant per year, as in the Track record score.
Not in this recordDisinfection by-products weren't monitored in this dataset
No result is not a pass. Your utility's annual water quality report may list them, and a certified lab test covers your own tap.
Health-based violations, last 10 years
Every filing is listed; the Track record score counts at most one per contaminant per year.
The record describes water leaving treatment and samples across the system. Pipes, solder and fixtures inside a building can add lead the record can’t see, especially in older buildings with lead service lines.
Affiliate linksPurityMap earns a commission from these links. "Best choice" and "Budget pick" go to certified products first; commission never decides them. As an Amazon Associate, PurityMap earns from qualifying purchases. Affiliate disclosure
★ Best choice: Aquasana Claryum 2-Stage Under-Sink Filter (AQ-5200), certified for PFOA, PFOS and lead.
Reverse osmosisiSpring RCC7AK Alkaline Reverse Osmosis SystemiSpring · It treats only the water from its own faucet and sends part of the water to the drain; the NSF listing for the plain RCC7AK covers dissolved solids, not lead or PFAS.Use code REFISPRING at checkout: 10% off your first iSpring order.
Reverse osmosisiSpring RO5004F Tankless Reverse Osmosis System with UViSpring · Its PFAS and lead reduction claims are iSpring's own, with no third-party certification named for this model, and it treats only the water at its own faucet.Use code REFISPRING at checkout: 10% off your first iSpring order.
Reverse osmosisWaterdrop X12 Reverse Osmosis SystemWaterdrop · Its IAPMO NSF/ANSI 58 certification covers TDS reduction only, so its PFAS and lead claims rest on Waterdrop's own SGS lab testing.
Whole-houseiSpring WGB32B-PFKS PFAS & Heavy Metals Whole House FilteriSpring · It does not reduce total dissolved solids or soften hard water, and its PFAS result comes from SGS lab testing rather than an NSF/ANSI certification.Use code REFISPRING at checkout: 10% off your first iSpring order.
PurityMap earns a commission from these links. "Best choice" and "Budget pick" go to certified products first; commission never decides them. As an Amazon Associate, PurityMap earns from qualifying purchases. Affiliate disclosure.
Lead service lines
Ask your utility first
Horsham Water&sewer Authority reported 4 galvanized service lines to replace in EPA’s inventory (2026Q2). Many utilities replace these lines for free or share the cost. Ask Horsham Water&sewer Authority whether your home’s line is on its list before you pay anyone.
Local help
Think your plumbing may be adding lead?
Call to be connected with a local plumbing provider about lead service lines, repiping or fixture replacement.
Your path: I live in an older buildingLead from plumbing is the main question
Older buildings may have lead service lines, solder or fixtures. Horsham’s utility reported 4 galvanized service lines in EPA’s inventory. Test first-draw water, then filter if needed.
8 of 29 PFAS tested were detected in Horsham’s record (PFOS 33.8 ng/L, PFOA 17.5 ng/L and PFHxS 10.6 ng/L, and more); 3 above their limit. If PFAS matters to you, a filter certification names each compound it covers.
Look forNSF/ANSI 53 or 58, with each compound you care about named on the listing
Your path: My water tastes of chlorineThe disinfectant is not in this record
Most utilities keep chlorine or chloramine in the pipes. A carbon filter certified for taste and odor reduces either; your utility can tell you which it uses.
PurityMap does not give a safe/unsafe verdict; it shows what the public records measured. For Horsham, PFOS 33.8 ng/L (limit 4 ng/L), PFOA 17.5 ng/L (limit 4 ng/L) and PFHxS 10.6 ng/L (limit 10 ng/L) were measured in one EPA sample each, above the limits EPA set in 2024 (not a violation: the limits are judged on a yearly average, due 2029). HORSHAM WATER&SEWER AUTHORITY (PWSID PA1460033) has a Purity Score of 56/100 (confidence: moderate), assessed at the water-system level and computed only from contaminants that were measured. Water can change in your own pipes, so a certified test is the only way to know what comes out of your tap. What we found →
Who provides tap water in Horsham?+
HORSHAM WATER&SEWER AUTHORITY (PWS ID PA1460033) is the public water system on record for Horsham, Pennsylvania, serving about 26,000 people. Confirm the utility on your water bill before acting on a specific finding. Water utility →
Where does Horsham get its drinking water?+
Surface water (primary source of record in EPA SDWIS). Water utility →
Are PFAS "forever chemicals" in Horsham's water?+
Yes. In EPA's UCMR 5 testing (2024-02-20 to 2025-08-18), PFOS was measured at 33.8 ng/L in one EPA sample, above the 4 ng/L limit EPA set in 2024, PFOA was measured at 17.5 ng/L in one EPA sample, above the 4 ng/L limit EPA set in 2024 and PFHxS was measured at 10.6 ng/L in one EPA sample, above the 10 ng/L limit EPA set in 2024. EPA's 2024 limits are judged on a yearly average, and water systems have until 2029 to meet them, so a single sample is not a violation. PFBS (5.7 ng/L, below the 2,000 ng/L EPA health advisory) and PFHxA (7.1 ng/L, below the 400,000 ng/L state limit) were also detected. PFBA (41.4 ng/L), PFHpA (4.4 ng/L) and PFPeA (65.3 ng/L) were also detected; they have no federal or state limit. Reverse osmosis and filters certified to NSF/ANSI 53 for PFOA/PFOS reduce them at the tap. What we found →
Is there lead in Horsham's tap water?+
Lead is not in Horsham's current published record. Lead usually enters from a building's own pipes and fixtures, so a certified home test is the way to know yours. Your household →
What does the latest Horsham water report show?+
PurityMap's current record for Horsham holds 31 findings: 4 above a reference, 2 detected within the reference, 3 detected with no limit and 22 not detected. Each finding links to its dated public record; a parameter that was never monitored is shown as pending, not as a pass. Records →
EPA SDWIS, EPA UCMR 5 and utility reports, each dated and linked.
02Normalize
Units converted to one basis; a non-detect kept distinct from zero.
03Classify
Each result tagged by reference type: MCL, action level, screening level or aesthetic.
04Compare to the named reference
Every value sits against its own reference, never a blended one.
05Score
Measured subjects summarised at the water-system level; an open health-based violation caps the score.
06Match treatment
Treatment is matched to what was found; a product is called certified only when its current certification names it.
What the Purity Score means: a summary of this water system’s published record, capped while a health-based violation is open. It is not a test of any tap. HORSHAM WATER&SEWER AUTHORITY · PWSID PA1460033 · Purity Score 56/100 (Fair) · Confidence: moderate · Assessed at the water-system level
Lead at Horsham Water&sewer Authority: not detected (90th percentile, 2025 monitoring period). Lead has no taste, so a taste neither shows nor rules it out.
ZIP codes in Horsham
A ZIP code is a postal area, not a water service area. Your water bill names your supplier.