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Which report this is
This page summarizes the Town of Gilbert's 2025 Annual Drinking Water Quality Report, published in June 2026, which reports testing done in 2025. It's the newest report on Gilbert's water quality reports page.1,2 It covers Town of Gilbert water only. Chandler and Tempe publish their own reports; see our Chandler report summary.
Gilbert's water comes from two surface water treatment plants and groundwater. The North Water Treatment Plant treats Salt and Verde River water from SRP canals. The Santan Vista plant, shared with Chandler, treats Colorado River water from the CAP canal. Twenty town wells supplement them.1
Key numbers from the 2025 report
| What | 2025 result | Notes |
|---|---|---|
| Total hardness | Average 184.44 mg/L (10.79 gpg); range 113–300 mg/L (6.61–17.54 gpg) | From the report's additional monitoring table. No federal limit.1 |
| Total dissolved solids (TDS) | Average 801 mg/L; range 674–984 | EPA's non-enforceable guideline is 500 mg/L.1,3 |
| Disinfectant residual | Chlorine: 0.20–1.99 ppm; average 0.92 ppm | Limit (MRDL) is 4 ppm. The report lists no chloramine.1 |
| Sodium | No published figure | The 2025 report doesn't list sodium.1 |
| pH | Average 7.79; range 7.34–8.14 | EPA guideline 6.5–8.5.1,3 |
| Alkalinity | Average 134.69 mg/L; range 113.4–174.5 | 1 |
| Calcium and magnesium | No published figure | Not listed separately in the 2025 report.1 |
| Arsenic | ND–12 ppb; average 6.3 | Limit 10 ppb. The report marks no violation and notes compliance is based on a running average, not the highest single result.1 |
| Nitrate | 0.30–8.32 ppm; average 4.59 | Limit 10 ppm.1 |
| Fluoride | ND–1.04 ppm; average 0.58 | Limit 4 ppm. Gilbert adds fluoride at its two treatment plants, targeting 0.7 ppm.1 |
| Chromium (total) | ND–17 ppb; average 8.1 | Limit 100 ppb.1 |
| Uranium | ND–4.8 ppb; average 2.7 | Limit 30 ppb.1 |
| Total trihalomethanes (TTHM) | 9–106 ppb; average 45 | Disinfection byproduct. Limit 80 ppb, based on a running average. The report marks no violation.1 |
| Haloacetic acids (HAA5) | ND–35 ppb; average 13 | Disinfection byproduct. Limit 60 ppb.1 |
| Bromate | ND–7.4 ppb; average 2.3 | Disinfection byproduct. Limit 10 ppb.1 |
| PFAS (wellheads) | Detected at Well 7 and Well 16 wellheads, Aug. and Oct. 2025; for example PFOA 0.00811 and 0.00883 ppb (8.11 and 8.83 ppt) at Well 7 | Both wells were taken offline as a precaution, according to the report.1 |
| Lead | 90th percentile 0.312 ppb; 0 above the action level | Action level 15 ppb. The report doesn't say which year these samples are from.1 |
| Copper | 90th percentile 0.089 ppm; 0 above the action level | Action level 1.3 ppm.1 |
ppm = parts per million (mg/L). ppb = parts per billion. ppt = parts per trillion. ND = not detected. Hardness, TDS, pH and alkalinity come from the report's additional monitoring table.1
What isn't published
Sodium, calcium and magnesium: the 2025 report doesn't list them. Hardness and TDS are given as townwide averages and ranges, with no figure by area or ZIP code.1 For a reading at your tap, test it or ask a dealer to.
Notices in the report
The report lists late reporting of compliance samples for 2024 and 2025 (chlorine, turbidity, arsenic, nitrate, total organic carbon, alkalinity, disinfection byproducts and coliform sampling) and the corrective actions Gilbert took.1
What this means for home treatment
- Scale: the 10.79 gpg average is hard water, and the range runs to 17.54 gpg, so test your tap before setting a softener. See softener cost in Chandler, Gilbert & Tempe and hard water in Chandler, Gilbert & Tempe.
- TDS and taste: TDS averages 801 mg/L. TDS reduction is a required claim for RO systems certified to NSF/ANSI 58. Check a unit's listing for anything else it's certified to reduce, such as PFAS.4
- Chlorine taste: carbon filters certified to NSF/ANSI 42 target chlorine taste and odor.5
Frequently asked questions
How hard is Gilbert water?
Gilbert's 2025 Annual Drinking Water Quality Report lists total hardness averaging 184.44 mg/L, or 10.79 grains per gallon, with a range of 113 to 300 mg/L (6.61 to 17.54 gpg).
What is the TDS of Gilbert tap water?
Gilbert's 2025 report lists total dissolved solids averaging 801 mg/L, with a range of 674 to 984 mg/L. EPA's non-enforceable secondary guideline is 500 mg/L.
Does Gilbert use chlorine or chloramine?
Gilbert's 2025 report lists chlorine at 0.20 to 1.99 ppm with an average of 0.92 ppm, against a limit of 4 ppm. It doesn't list chloramine.
How much sodium is in Gilbert water?
No published figure. Gilbert's 2025 report doesn't list sodium.
Did Gilbert find PFAS in 2025?
The 2025 report lists PFAS detections at the Well 7 and Well 16 wellheads in August and October 2025, and says both wells were taken offline as a precaution. It says detection is limited to a few sites and isn't townwide.
Does this report cover Chandler and Tempe?
No. It covers Town of Gilbert water only. Chandler and Tempe publish their own reports.
More water quality reports: Chandler · Mesa · Scottsdale · Phoenix · Tucson · Chandler, Gilbert & Tempe water treatment pros
Sources
- Town of Gilbert 2025 Annual Drinking Water Quality Report, PDF (published June 2026)
- Town of Gilbert: Water Quality Reports page
- 40 CFR 143.3: secondary maximum contaminant levels
- NSF: NSF/ANSI 58 reverse osmosis systems
- NSF: NSF/ANSI 42, 53 and 401 filtration standards
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