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About TPU > Services > Water > About Tacoma Water > Water Quality > 2025 Water Quality Report > Water Quality Table

Water Quality Table

A multi-section table shows water-quality test results from groundwater sources, the treatment plant, the distribution system, and household taps. For each contaminant, the table lists regulatory limits, highest detected levels, detection ranges, compliance status, and potential contamination sources. All listed contaminants meet regulations, except items noted as unregulated. Contaminants include arsenic, nitrate, trichloroethylene, chloroform, fluoride, turbidity, disinfection byproducts, chlorine residual, total coliform, lead, and copper.

Detailed Accessible Table Description

The image presents a multi-section table summarizing water‑quality testing results.

The table is divided into five major sections:

  1. Regulated at our groundwater sources
  2. Unregulated at our groundwater sources
  3. Regulated at our treatment plant
  4. Regulated in our distribution system
  5. Regulated at your tap

Each section contains a grid of columns showing contaminant names, regulatory limits, detected levels, compliance status, and potential sources of contamination. All numerical units (ppb, ppm, NTU) are shown in the table as printed.

Regulated at our groundwater sources

Columns:

Constituent; Highest level allowed (MCL); Highest level detected; Ideal goal (MCLG); Range of level detected; Regulation met; Potential sources of contaminant.

Rows:
  • Arsenic
    • Highest level allowed: 10 ppb
    • Highest level detected: 1.7 ppb (2021)
    • Ideal goal: 0
    • Range detected: 0 to 1.7 ppb
    • Regulation met: Yes
    • Potential sources: Natural erosion
  • Nitrate
    • Highest level allowed: 10 ppm
    • Highest level detected: 4.0 ppm (2025)
    • Ideal goal: 10 ppm
    • Range detected: 0 to 4.0 ppm
    • Regulation met: Yes
    • Potential sources: Agricultural uses, septic
  • Trichloroethylene
    • Highest level allowed: 5 ppb
    • Highest level detected: 1.6 ppb (2025)
    • Ideal goal: 0
    • Range detected: 0 to 1.6 ppb
    • Regulation met: Yes
    • Potential sources: Industrial contamination

Unregulated at our groundwater sources

Columns:

Constituent; MCL; Highest level detected; MCLG; Range of level detected; Regulation met; Potential sources of contaminant.

Row:
  • Chloroform
    • MCL: Not regulated (N/R)
    • Highest level detected: 1.3 ppb (2025)
    • MCLG: N/R
    • Range detected: 0 to 13 ppb; average 0.26 ppb
    • Regulation met: N/R
    • Potential sources: Industrial contamination

Regulated at our treatment plant

Columns:

Constituent; MCL; Highest level detected; MCLG; Range of level detected; Regulation met; Potential sources of contaminant.

Rows:
  • Fluoride
    • MCL: 4 ppm
    • Highest level detected: 0.96 ppm
    • MCLG: 4 ppm
    • Range detected: 0.04 to 0.96 ppm
    • Regulation met: Yes
    • Potential sources: Treatment additive
  • Turbidity
    • MCL: 1 NTU
    • Highest level detected: 0.036 NTU
    • MCLG: Not applicable
    • Range detected: 0.017 to 0.036 NTU
    • Regulation met: Yes
    • Potential sources: Soil erosion

Regulated in our distribution system

Columns:

Disinfection byproducts (or disinfectant/residual/coliform category); Highest running annual average allowed; Our running annual average; MCLG; Range of level detected; Regulation met; Potential sources of contaminant.

Rows:
  • Total Trihalomethanes
    • Allowed: 80 ppb average
    • Our average: 12.8 ppb
    • MCLG: Not applicable
    • Range detected: 3.58 to 35.4 ppb
    • Regulation met: Yes
    • Source: Disinfection interaction
  • Haloacetic Acids
    • Allowed: 60 ppb average
    • Our average: 2.0 ppb
    • MCLG: Not applicable
    • Range detected: less than 1 to 4.55 ppb
    • Regulation met: Yes
    • Source: Disinfection interaction
  • Bromate
    • Allowed: 10 ppb
    • Our average: 0
    • MCLG: 0
    • Range detected: 0
    • Regulation met: Yes
    • Source: Disinfection interaction
  • Chlorine Residual
    • Allowed: 4 ppm
    • Our average: Not applicable (N/A)
    • MCLG: 4 ppm (MRDLG)
    • Range detected: 0.27 to 1.66 ppm
    • Regulation met: Yes
    • Source: Treatment additive
  • Total Coliform
    • Allowed: Less than 5 percent positive
    • Our average: 0.000 percent
    • MCLG: 0
    • Range detected: 0 of 2,469 sites positive
    • Regulation met: Yes
    • Source: Sampling technique

Regulated at your tap (Lead and copper sampling)

A heading notes that lead and copper sampling was conducted in 2025, required once every three years.

Columns:

Constituent; 90% of samples must be below the action level (AL); 90% of samples were at or below this level; MCLG; Number of sites above the action level; Regulation met; Potential sources of contaminant.

Rows:
  • Lead
    • Action level: 15 ppb
    • 90% sample result: Not detected (N/D)
    • MCLG: 0
    • Number of sites above action level: 0 of 51 sites
    • Regulation met: Yes
    • Potential sources: Household plumbing
  • Copper
    • Action level: 1.3 ppm
    • 90% sample result: Not detected (N/D)
    • MCLG: 1.3 ppm
    • Number of sites above action level: 0 of 51 sites
    • Regulation met: Yes
    • Potential sources: Household plumbing