This page summarizes EPA Fifth Unregulated Contaminant Monitoring Rule (UCMR 5, 2023–2025) drinking-water monitoring records linked to ZIP codes in Delaware, as processed for the PFAS Estimator national dataset. Data updated: July 2026.
| Compound | Applicable threshold | ZIP codes detected | At/above threshold | Mean detected | Maximum detected |
|---|---|---|---|---|---|
| PFOA | 0.004 µg/L (MCL) | 35 (64.8% of state) | 35 (100.0%) — all detections at/above limit by construction | 0.0163 µg/L | 0.036 µg/L |
| PFOS | 0.004 µg/L (MCL) | 20 (37.0% of state) | 20 (100.0%) — all detections at/above limit by construction | 0.0066 µg/L | 0.014 µg/L |
| PFHxS | 0.01 µg/L (MCL) | 11 (20.4% of state) | 0 (0.0% of detected) | 0.0079 µg/L | 0.0089 µg/L |
| PFNA | 0.01 µg/L (MCL) | 14 (25.9% of state) | 14 (100.0% of detected) | 0.0122 µg/L | 0.02 µg/L |
| PFBS | 2.0 µg/L (HI reference) | 35 (64.8% of state) | not calculated¹ | 0.0057 µg/L | 0.0127 µg/L |
| Lithium | 7.36 µg/L (reference, not a regulatory limit) | 12 (22.2% of state) | 12 (100.0%) at/above reference | 22.35 µg/L | 37.2 µg/L |
| PFPeA | — (no federal limit) | 37 (68.5% of state) | — | 0.0443 µg/L | 0.1229 µg/L |
| PFBA | — (no federal limit) | 28 (51.9% of state) | — | 0.0419 µg/L | 0.1472 µg/L |
| PFHpA | — (no federal limit) | 28 (51.9% of state) | — | 0.019 µg/L | 0.039 µg/L |
| 6:2 FTS | — (no federal limit) | 1 (1.9% of state) | — | 0.18 µg/L | 0.18 µg/L |
| PFDA | — (no federal limit) | 13 (24.1% of state) | — | 0.0047 µg/L | 0.0047 µg/L |
54 ZIP codes with at least one recorded PFAS detection. Click a ZIP code to view its full compound-level results.
| ZIP code | Compounds detected | At/above threshold |
|---|---|---|
| 19701 | 9 | Yes (3) |
| 19702 | 9 | Yes (3) |
| 19703 | 7 | Yes (2) |
| 19707 | 7 | Yes (2) |
| 19708 | 5 | Yes (1) |
| 19710 | 5 | Yes (1) |
| 19711 | 9 | Yes (3) |
| 19713 | 9 | Yes (3) |
| 19720 | 9 | Yes (3) |
| 19732 | 5 | Yes (1) |
| 19733 | 7 | Yes (2) |
| 19801 | 7 | Yes (2) |
| 19802 | 7 | Yes (2) |
| 19803 | 7 | Yes (2) |
| 19804 | 9 | Yes (3) |
| 19805 | 7 | Yes (2) |
| 19806 | 5 | Yes (1) |
| 19807 | 5 | Yes (1) |
| 19808 | 5 | Yes (1) |
| 19809 | 7 | Yes (2) |
| 19810 | 7 | Yes (2) |
| 19850 | 5 | Yes (1) |
| 19880 | 5 | Yes (1) |
| 19884 | 5 | Yes (1) |
| 19898 | 5 | Yes (1) |
| 19899 | 5 | Yes (1) |
| 19901 | 1 | No |
| 19902 | 1 | No |
| 19903 | 1 | No |
| 19904 | 1 | No |
| 19930 | 1 | Yes (1) |
| 19934 | 1 | No |
| 19936 | 1 | No |
| 19939 | 1 | Yes (1) |
| 19940 | 4 | Yes (2) |
| 19943 | 1 | No |
| 19944 | 1 | Yes (1) |
| 19945 | 1 | Yes (1) |
| 19946 | 1 | No |
| 19947 | 9 | Yes (3) |
| 19951 | 3 | Yes (1) |
| 19958 | 5 | Yes (2) |
| 19962 | 1 | No |
| 19963 | 1 | No |
| 19966 | 3 | Yes (1) |
| 19967 | 1 | Yes (1) |
| 19968 | 3 | Yes (1) |
| 19969 | 3 | Yes (1) |
| 19970 | 1 | Yes (1) |
| 19971 | 6 | Yes (2) |
| 19973 | 1 | No |
| 19975 | 3 | Yes (1) |
| 19977 | 5 | Yes (2) |
| 19979 | 1 | No |
Results are based on EPA UCMR 5 monitoring data (2023–2025), linked to ZIP codes via Public Water System Identifier. Non-detections are not present in this analytic dataset. For each compound and ZIP code, the highest observed concentration across the monitoring period is retained; this characterizes the upper bound of observed drinking-water concentrations, not a long-term average or an individual exposure estimate. A single water system may serve multiple ZIP codes, so the same monitoring record can appear for more than one ZIP in this table. ZIP-code assignment reflects water-system service area geography and does not establish individual household exposure. Private wells are not represented unless served by a monitored public water system. PFOA and PFOS are reported by detection prevalence because the UCMR 5 reporting limit equals their federal MCL. A full PFBS Hazard Index is not calculated because co-located, same-event multi-compound readings are not retained in this dataset. Lithium has no federal Maximum Contaminant Level; 7.36 µg/L is an evidence-based reference concentration from a prospective cohort study, not a regulatory threshold.
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