San Juan metro area tap water: what EPA testing found

What the data shows

• PFOS above EPA’s drinking-water limit

  In UCMR 5 testing (2024–2025), PFOS averaged up to 6.25 ng/L (limit 4.0) at the worst sampling point. Utilities must meet the limit by 2029 under the current rule; EPA has proposed letting systems ask for until 2031 (not final).

  What fits: Pick a filter whose listing certifies PFOA/PFOS (or total PFAS) reduction under NSF/ANSI 53 or 58. Under-sink reverse osmosis units and some carbon filters and pitchers carry it; the certification for the exact model is what counts, not the filter type.

  Certified — IAPMO listing, checked 16 Oct 2026

  • Culligan with ZeroWater Technology 10 Cup PitcherPitcher filter · ZEROP10
  • PUR PLUS Lead Reducing Pitcher & Dispenser Replacement FilterPitcher filter · PPF951K
  • ZeroWater 5-Stage Replacement FilterPitcher filter · ZR-017
  • Culligan Scout 2.25 Gallon Gravity Countertop System with MaxClear…Countertop dispenser · MCSP
  • PUR Faucet Filtration System, VerticalFaucet-mount filter · FM-3333B
  • PUR PLUS Faucet Filtration System – Horizontal, ChromeFaucet-mount filter · PFM400H
  • AquaTru Classic Countertop Reverse Osmosis Water PurifierCountertop reverse osmosis · AT2000
  • Aquasana Claryum Direct Connect Under Sink Water FilterUnder-sink filter · AQ-MF-1
  • Culligan EZ-Change Under Sink Drinking Water Filtration SystemUnder-sink filter · US-EZ-4
  • APEC Water Tankless RO System 4 Stage Water Filter, 1000 GPD Reverse…Under-sink reverse osmosis · ROTL-A1000
  • Waterdrop 800 GPD Tankless Reverse Osmosis System - Waterdrop G3P800Under-sink reverse osmosis · WD-G3P800
  • Waterdrop G3P600 Reverse Osmosis System - Waterdrop G3P600Under-sink reverse osmosis · WD-G3P600

  Brand says certified — not found in IAPMO’s listing; check NSF

  • Aquasana Clean Water MachineCountertop dispenser · AQ-CWM2-B · check NSF’s listing yourself
  • Aquasana Claryum 2-Stage Under Sink Water FilterUnder-sink filter · AQ-6200 · check NSF’s listing yourself
  • Aquasana Claryum 3-Stage Max Flow Under Sink Water FilterUnder-sink filter · AQ-6300M · check NSF’s listing yourself
  • Aquasana Claryum 3-Stage Under Sink Water FilterUnder-sink filter · AQ-6300 · check NSF’s listing yourself
  • A. O. Smith High Efficiency Reverse Osmosis SystemUnder-sink reverse osmosis · AOS-HERO-CHR · check NSF’s listing yourself
  • Aquasana SmartFlow Reverse Osmosis Water FilterUnder-sink reverse osmosis · AQ-SFRO2 · check NSF’s listing yourself
  • Culligan Aquasential Smart Reverse Osmosis Drinking Water…Under-sink reverse osmosis · Aquasential Smart RO · check NSF’s listing yourself
  • Waterdrop Instant Hot Water Dispenser, Reverse Osmosis System, K6Under-sink reverse osmosis · WD-K6-W · check NSF’s listing yourself
  • Waterdrop X Series Reverse Osmosis System, X12Under-sink reverse osmosis · WD-X12 · check NSF’s listing yourself
  • Aquasana HealthShield Whole House Water Filtration SystemWhole-house filter · WH-HS · check NSF’s listing yourself

  NSF’s and WQA’s listings can’t be checked automatically; each product page also links to WQA’s.

• Treatment-technique violation (turbidity or filtration)

  64 health-based violations since 2016, the latest starting 2026-04-01; 11 not yet marked returned to compliance.

  What fits: These are treatment-technique rules for the plant (turbidity and filtration). The utility fixes them; follow its public notices, including any boil-water advisory.

• Trihalomethanes (TTHM) over the limit

  13 health-based violations since 2016, the latest starting 2021-01-01.

  What fits: Trihalomethanes are by-products of disinfection. Carbon filters certified for VOC reduction (NSF/ANSI 53, tested with chloroform as the surrogate) or for TTHM reduction cover them.

  Certified — IAPMO listing, checked 16 Oct 2026

  • PUR Pitcher & Dispenser Replacement FilterPitcher filter · PPF900Z
  • PUR PLUS Lead Reducing Pitcher & Dispenser Replacement FilterPitcher filter · PPF951K
  • PUR Faucet Filtration System, VerticalFaucet-mount filter · FM-3333B
  • PUR PLUS Faucet Filtration System – Horizontal, ChromeFaucet-mount filter · PFM400H
  • Brita Hub Countertop Water Filter System with Brita Hub FilterCountertop filter · 87340
  • AquaTru Classic Countertop Reverse Osmosis Water PurifierCountertop reverse osmosis · AT2000
  • Aquasana Claryum Direct Connect Under Sink Water FilterUnder-sink filter · AQ-MF-1
  • Culligan EZ-Change Under Sink Drinking Water Filtration SystemUnder-sink filter · US-EZ-4

  Brand says certified — not found in IAPMO’s listing; check NSF

  • Brita Elite Replacement Filter, formerly Longlast+Pitcher filter · OB06 · check NSF’s listing yourself
  • Aquasana Clean Water MachineCountertop dispenser · AQ-CWM2-B · check NSF’s listing yourself
  • Brita Elite Advanced Water Filter Faucet System with Brita…Faucet-mount filter · FF-100 · check NSF’s listing yourself
  • A. O. Smith High Efficiency Reverse Osmosis SystemUnder-sink reverse osmosis · AOS-HERO-CHR · check NSF’s listing yourself
  • Aquasana SmartFlow Reverse Osmosis Water FilterUnder-sink reverse osmosis · AQ-SFRO2 · check NSF’s listing yourself
  • Culligan Aquasential Smart Reverse Osmosis Drinking Water…Under-sink reverse osmosis · Aquasential Smart RO · check NSF’s listing yourself
  • Aquasana HealthShield Whole House Water Filtration SystemWhole-house filter · WH-HS · check NSF’s listing yourself

  NSF’s and WQA’s listings can’t be checked automatically; each product page also links to WQA’s.

• Haloacetic acids (HAA5) over the limit

  3 health-based violations since 2016, the latest starting 2020-10-01.

  What fits: Haloacetic acids are also disinfection by-products. None of the products we track lists a certified haloacetic-acid claim; the utility has to fix the cause.

• Coliform or groundwater-rule violation

  2 health-based violations since 2016, the latest starting 2019-04-01.

  What fits: Coliform and groundwater-rule violations are fixed at the system. Follow the utility’s notices; if it issues a boil-water advisory, boil or use bottled water until it is lifted.

• Lead from home plumbing (not in this data)

  UCMR 5 does not test for lead, and lead usually enters water from service lines and plumbing inside buildings. Your utility’s lead service line inventory says whether your address is served by a lead line.

  What fits: Lead comes from lead service lines, solder and fixtures inside buildings, not usually from the treatment plant. Use a filter certified for lead reduction (NSF/ANSI 53 or 58) at the tap you drink from.

  Certified — IAPMO listing, checked 16 Oct 2026

  • Brita Elite Replacement Filter, formerly Longlast+Pitcher filter · OB06
  • Culligan with ZeroWater Technology 10 Cup PitcherPitcher filter · ZEROP10
  • PUR PLUS Lead Reducing Pitcher & Dispenser Replacement FilterPitcher filter · PPF951K
  • ZeroWater 5-Stage Replacement FilterPitcher filter · ZR-017
  • Culligan Scout 2.25 Gallon Gravity Countertop System with MaxClear…Countertop dispenser · MCSP
  • PUR Faucet Filtration System, VerticalFaucet-mount filter · FM-3333B
  • PUR PLUS Faucet Filtration System – Horizontal, ChromeFaucet-mount filter · PFM400H
  • AquaTru Classic Countertop Reverse Osmosis Water PurifierCountertop reverse osmosis · AT2000
  • Aquasana Claryum Direct Connect Under Sink Water FilterUnder-sink filter · AQ-MF-1
  • Culligan EZ-Change Under Sink Drinking Water Filtration SystemUnder-sink filter · US-EZ-4
  • Waterdrop 800 GPD Tankless Reverse Osmosis System - Waterdrop G3P800Under-sink reverse osmosis · WD-G3P800
  • Waterdrop G3P600 Reverse Osmosis System - Waterdrop G3P600Under-sink reverse osmosis · WD-G3P600

  Brand says certified — not found in IAPMO’s listing; check NSF

  • LifeStraw Home 7-Cup Glass Water Filter PitcherPitcher filter · LSH7SPC101 · check NSF’s listing yourself
  • Aquasana Clean Water MachineCountertop dispenser · AQ-CWM2-B · check NSF’s listing yourself
  • Brita Elite Advanced Water Filter Faucet System with Brita…Faucet-mount filter · FF-100 · check NSF’s listing yourself
  • Brita Hub Countertop Water Filter System with Brita Hub FilterCountertop filter · 87340 · check NSF’s listing yourself
  • Aquasana Claryum 2-Stage Under Sink Water FilterUnder-sink filter · AQ-6200 · check NSF’s listing yourself
  • Aquasana Claryum 3-Stage Max Flow Under Sink Water FilterUnder-sink filter · AQ-6300M · check NSF’s listing yourself
  • Aquasana Claryum 3-Stage Under Sink Water FilterUnder-sink filter · AQ-6300 · check NSF’s listing yourself
  • A. O. Smith High Efficiency Reverse Osmosis SystemUnder-sink reverse osmosis · AOS-HERO-CHR · check NSF’s listing yourself
  • APEC Water Tankless RO System 4 Stage Water Filter, 1000 GPD Reverse…Under-sink reverse osmosis · ROTL-A1000 · check NSF’s listing yourself
  • APEC Water Ultimate 5-Stage 90 GPD High Output Reverse Osmosis Water…Under-sink reverse osmosis · RO-90 · check NSF’s listing yourself
  • Aquasana SmartFlow Reverse Osmosis Water FilterUnder-sink reverse osmosis · AQ-SFRO2 · check NSF’s listing yourself
  • Culligan Aquasential Smart Reverse Osmosis Drinking Water…Under-sink reverse osmosis · Aquasential Smart RO · check NSF’s listing yourself
  • iSpring RCC7AK, NSF Certified 75 GPD, Alkaline 6-Stage Reverse…Under-sink reverse osmosis · RCC7AK · check NSF’s listing yourself
  • Waterdrop X Series Reverse Osmosis System, X12Under-sink reverse osmosis · WD-X12 · check NSF’s listing yourself

  NSF’s and WQA’s listings can’t be checked automatically; each product page also links to WQA’s.

PFAS and lithium (EPA UCMR 5)

600 results from 5 sampling points, 4 Apr 2024 to 22 Jan 2025. Averages count results below EPA’s reporting level as zero, as the PFAS rule does. Every number links to EPA’s UCMR 5 Data Finder (search PWSID PR0002591). Limits: EPA PFAS rule.

* PFHxS, PFNA and HFPO-DA limits (and the PFAS hazard index) are in the rule, but EPA proposed on 20 May 2026 to rescind them; not final as of 16 Oct 2026. UCMR 5 results are screening data, not compliance results: compliance uses quarterly running averages from 2029. Source file: EPA UCMR 5 occurrence data (dated 15 Oct 2026).

Sampling points averaging above a limit

Health-based violations since 2016

Source: EPA SDWIS via Envirofacts and the ECHO report for PR0002591, retrieved 16 Oct 2026.

Hardness

The utility’s latest water report doesn’t publish a hardness figure (checked 16 Oct 2026). A home test kit or a call to the utility gives it; then use the softener calculator.

Places and ZIP codes served

San Juan.

00901

ZIP codes the system reported to EPA for UCMR 5; place names from GeoNames (CC BY 4.0). A ZIP code can be split between systems.