Recycled Water Quality Data

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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 2019

Constituent Unit Average Range
pH standard unit 7.18 6.66 - 7.61
Alkalinity (as CaCO3) mg/L 306 225 - 429
Bicarbonate (as CaCO3)  mg/L  306 225 - 429 
Calcium mg/L 51 30.4 - 72
Magnesium mg/L 33 19 - 52
Calcium Hardness (as CaCO3) mg/L 126

76 - 180

Total Hardness (as CaCO3) mg/L 263 186 - 352
Chloride mg/L 181 148 - 211
Conductivity µmhos/cm 1427 957 - 1775
Total Dissolved Solids mg/L 724 635 - 860
Ammonia (as N) mg/L 28.1 11 - 33.8
Nitrite (as N) mg/L  2.50 0.22 - 5.01
Nitrate (as N) mg/L 1.12 0.10 - 9.21
Total Kjeldahl Nitrogen mg/L 25 13 - 34
Sulfate mg/L 138 98.2 - 183
Arsenic µg/L 1.0 <1.0 - 1.3
Boron
mg/L
0.74 0.49 - 1.09
Chromium
µg/L
0.57 <0.50 - 0.93
Manganese
µg/L
50.3 34.4 - 71.6
Potassium
mg/L
15.7 13.1 - 17.7
Selenium µg/L 1.0 <1.0 - 1.3
Silica (Total) mg/L 18.1 13.6 - 22.9
Sodium mg/L 158 139 - 177
Total Coliform Bacteria MPN  < 2* < 2 - 80
 
 
*Median
Abbreviations: mg/L = milligrams per liter; µmhos = micromhos per centimeter; µg/L = micrograms per liter; MPN = most probable number
 
Most plants thrive with recycled water's higher nutrient content but some plants are sensitive to the higher salt content. The Tri-Valley Water-Wise website has a list of plants known to tolerate higher salt content, as does East Bay Municipal Utility District's award-winning book, Plants and Landscapes for Summer-Dry Climates of the San Francisco Bay Region.