Recycled Water Quality Data

Lab technician titrating a water sample

Recycled water used in Dublin and San Ramon meets all regulatory requirements for unrestricted reuse as well as guidelines for managing salts in the groundwater basin under the Tri-Valley.

The DSRSD laboratory tests the parameters listed in the table on a monthly basis to ensure recycled water used for irrigation will not harm landscaping, as well as to monitor salts returned to the watershed.

Recycled Water Quality Data, Calendar Year 2025

Constituent Unit Average Range
pH standard unit 7.3 7.07 - 7.4
Total Alkalinity (as CaCO3) mg/L 277 212 - 326
Bicarbonate (as CaCO3) mg/L 277 212 - 326
Calcium mg/L 45.7 34.4 - 62.4
Magnesium mg/L 26 15 - 41
Calcium Hardness (as CaCO3) mg/L 114.25 86 - 156
Total Hardness (as CaCO3) mg/L 222.58 166 - 312
Chloride mg/L 203 179 - 240
Conductivity µmhos/cm 1459.8 1341 - 1656
Total Dissolved Solids mg/L 745.75 670 - 888
Ammonia (as N) mg/L 30.64 14 - 40
Nitrite (as N) mg/L 2.10 <1 - 4.4
Nitrate (as N) mg/L 2.27 <0.50 - 5.4
Total Kjeldahl Nitrogen mg/L 31.67 16 - 39
Sulfate mg/L 143 111 - 181 
Arsenic µg/L 0.62 <0.50 - 0.63
Boron mg/L 0.48 0.40 - 0.59
Chromium µg/L <2 <2.0 - 0.54
Manganese µg/L 54.39 <50 -59
Potassium mg/L 15.975 14.6 - 18
Selenium µg/L 0.66 <0.5 - 0.93
Silica (Total) mg/L 15.275 11 - 20.7 
Sodium mg/L 167.42 150 - 190
Total Coliform Bacteria MPN/100 ml <1 (Median) <1 -20.3
Copper ug/L 7.15 2.9 -15
Lead ug/L <0.5 N/A
Zinc ug/L 10.23 7.8 -13

Abbreviations

  • mg/L = milligrams per liter
  • µmhos = micromhos per centimeter
  • µg/L = micrograms per liter
  • MPN = most probable number

 

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