# Washington Dc, DC — Drinking Water Quality (2023)

> Contaminant levels for the Washington Dc, DC public water system from its 2023 Consumer Confidence Report, compared to federal limits.

- Page: https://www.thewatermap.com/water/dc/washington-dc/2023
- JSON API: https://www.thewatermap.com/api/water/dc/washington-dc/2023
- Source: the utility's annual Consumer Confidence Report (CCR)
- Verification: transcribed by a model, cross-checked by a second model, approved before publishing
- Reporting year: 2023
- Contaminants measured: 30
- Contaminants with a federal limit: 11
- Contaminants at or above the federal limit: 1
- Part of The Water Map — https://www.thewatermap.com

## Contaminants measured

| Contaminant | Category | Measured level | Sampling context | Federal limit | Status |
|---|---|---|---|---|---|
| Chlorine | Disinfectants | 3 mg/L (Running annual avg) | System-wide | 4 mg/L (MCLG) | Within the limit |
| HAA5 | Disinfection byproducts | 37 ug/L (Running annual avg) | System-wide | 60 ug/L (MCL) | Within the limit |
| Perchlorate | Disinfection byproducts | 0.2 ug/L (Average) | System-wide | No federal limit | Detected — no federal limit |
| TTHM | Disinfection byproducts | 58 ug/L (Running annual avg) | System-wide | 80 ug/L (MCL) | Within the limit |
| Ammonia | Inorganic chemicals | 1 mg/L (Average) | System-wide | No federal limit | Detected — no federal limit |
| Chloride | Inorganic chemicals | 32 mg/L (Average) | System-wide | No federal limit | Detected — no federal limit |
| Fluoride | Inorganic chemicals | 0.7 mg/L (Maximum) | DC Drinking Water | 4 mg/L (MCLG) | Within the limit |
| Nitrate | Inorganic chemicals | 2 mg/L (Range) | DC Drinking Water | 10 mg/L (MCLG) | Within the limit |
| Sulfate | Inorganic chemicals | 47 mg/L (Average) | System-wide | No federal limit | Detected — no federal limit |
| Aluminum | Metals | 39 ug/L (Average) | System-wide | No federal limit | Detected — no federal limit |
| Arsenic | Metals | 0.4 ug/L (Maximum) | DC Drinking Water | 0 ug/L (MCLG) | Detected — no federal limit |
| Barium | Metals | 0.04 mg/L (Range) | DC Drinking Water | 2 mg/L (MCLG) | Within the limit |
| Calcium | Metals | 39 mg/L (Average) | System-wide | No federal limit | Detected — no federal limit |
| Iron | Metals | Not detected ug/L (Average) | System-wide | No federal limit | Detected — no federal limit |
| Lithium | Metals | 2 ug/L (Average) | System-wide | No federal limit | Detected — no federal limit |
| Magnesium | Metals | 9 mg/L (Average) | System-wide | No federal limit | Detected — no federal limit |
| Manganese | Metals | 0.3 ug/L (Average) | System-wide | No federal limit | Detected — no federal limit |
| Nickel | Metals | 0.3 ug/L (Average) | System-wide | No federal limit | Detected — no federal limit |
| Potassium | Metals | 3 mg/L (Average) | System-wide | No federal limit | Detected — no federal limit |
| Sodium | Metals | 22 mg/L (Average) | System-wide | No federal limit | Detected — no federal limit |
| Strontium | Metals | 187 ug/L (Average) | System-wide | No federal limit | Detected — no federal limit |
| Vanadium | Metals | Not detected ug/L (Average) | System-wide | No federal limit | Detected — no federal limit |
| Zinc | Metals | Not detected ug/L (Average) | System-wide | No federal limit | Detected — no federal limit |
| Perfluorohexanesulfonic acid | PFAS ("forever chemicals") | 0.2 (Average) | System-wide | 1.9 (MCL) | Within the limit |
| PFAS | PFAS ("forever chemicals") | 0.001 (Average) | System-wide | No federal limit | Detected — no federal limit |
| PFOA | PFAS ("forever chemicals") | 1.5 (Average) | System-wide | 1.9 (MCL) | Within the limit |
| PFOS | PFAS ("forever chemicals") | 2.1 (Average) | System-wide | 1.9 (MCL) | At or above the limit |
| Hardness | Physical & aggregate | 8 (Average) | System-wide | No federal limit | Detected — no federal limit |
| TOC | Physical & aggregate | 1.37 (Reported level) | DC Drinking Water | No federal limit | Detected — no federal limit |
| Dalapon | VOCs & pesticides | 1 ug/L (Range) | System-wide | 200 ug/L (MCLG) | Within the limit |

## What these contaminants are

- **Chlorine** — A disinfectant added to drinking water to kill bacteria and viruses. Effective and necessary, but high residual levels can cause taste and odor issues; the EPA caps the residual disinfectant level.
- **HAA5** — Haloacetic acids — a group of five disinfection byproducts formed when disinfectants react with organic matter. Long-term exposure above the federal limit is associated with an increased cancer risk.
- **Perchlorate** — A chemical used in rocket fuel and fireworks that can also form during disinfection. Can interfere with thyroid hormone production; has no national enforceable limit but is regulated in some states.
- **TTHM** — Total trihalomethanes — a group of four chemicals (including chloroform) formed when chlorine reacts with natural organic matter. Long-term exposure above the federal limit is linked to liver, kidney, and central-nervous-system effects and increased cancer risk.
- **Chloride** — A naturally occurring salt compound. Regulated only as a secondary (cosmetic) standard; high levels cause a salty taste and can corrode pipes.
- **Fluoride** — A mineral often added to drinking water to help prevent tooth decay. Beneficial at low levels, but long-term exposure above the federal limit can cause bone disease and tooth mottling.
- **Nitrate** — A compound from fertilizer runoff, septic systems, and erosion of natural deposits. Levels above the federal limit can cause 'blue baby syndrome,' a serious oxygen-transport condition in infants.
- **Sulfate** — A naturally occurring mineral from rock and soil. No health-based federal limit; high levels can have a laxative effect and a bitter taste.
- **Aluminum** — A common element sometimes used as a treatment coagulant. Regulated only as a secondary (cosmetic) standard; high levels can discolor water.
- **Arsenic** — A naturally occurring element that also enters water from industry and agriculture. A known human carcinogen; long-term exposure is linked to skin, bladder, and lung cancer.
- **Barium** — A metal from erosion of natural deposits and industrial discharge. Long-term exposure above the federal limit can raise blood pressure.
- **Calcium** — A naturally occurring mineral that contributes to water hardness. Not federally regulated for health; affects scaling and taste.
- **Iron** — A naturally occurring metal common in groundwater. Regulated only as a secondary (cosmetic) standard; causes rusty color, staining, and metallic taste.
- **Lithium** — A naturally occurring element found in some groundwater. No enforceable federal limit; on the EPA contaminant candidate list for further study.
- **Magnesium** — A naturally occurring mineral that contributes to water hardness. Not federally regulated for health; affects scaling and taste.
- **Manganese** — A naturally occurring metal from soil and rock. No enforceable federal limit; high levels stain fixtures and laundry and can affect taste, with a health advisory for infants.
- **Nickel** — A metal from natural deposits and industrial discharge. Long-term exposure can cause skin and other effects; monitored under EPA rules.
- **Potassium** — A naturally occurring mineral from rock and soil. Not federally regulated for health.
- **Sodium** — A naturally occurring salt component. Not federally regulated for health; relevant for people on sodium-restricted diets.
- **Zinc** — A naturally occurring metal that can also enter water from corroding pipes. Regulated only as a secondary (cosmetic) standard; high levels cause a metallic taste.
- **Perfluorohexanesulfonic acid** — Perfluorohexanesulfonic acid, a PFAS 'forever chemical.' Regulated by the EPA at 10 parts per trillion and included in the PFAS Hazard Index.
- **PFOA** — Perfluorooctanoic acid, a PFAS 'forever chemical' once used in nonstick and stain-resistant products. Linked to cancer, liver damage, and immune effects; the EPA set an enforceable limit of 4 parts per trillion.
- **PFOS** — Perfluorooctanesulfonic acid, a PFAS 'forever chemical' once used in firefighting foam and coatings. Linked to cancer, thyroid disease, and immune effects; the EPA set an enforceable limit of 4 parts per trillion.
- **Hardness** — A measure of dissolved calcium and magnesium minerals. Not federally regulated for health; affects scaling, soap use, and taste.
- **TOC** — Total organic carbon — a measure of organic material dissolved in the water. Not harmful itself, but it is the raw material that forms disinfection byproducts; removal is a treatment requirement.

## How to read this

- A water-quality report covers an entire service area, not a single address.
- 'Federal limit' is the EPA standard (MCL, action level, treatment technique, etc.) that the measured level is compared against.
- 'At or above the federal limit' means the utility's own reported figure met or exceeded that standard.

_Figures are the utility's own published numbers. Generated 2026-05-25 from thewatermap.com._