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 2017

Constituent Unit Average Range
pH standard unit 7.43 7.14 - 7.7
Alkalinity (as CaCO3) mg/L 310 250 - 370
Calcium mg/L 55 43 - 69
Magnesium mg/L 30 17 - 43
Calcium Hardness (as CaCO3) mg/L 138

108 - 172

Total Hardness (as CaCO3) mg/L 261 180 - 344
Chloride mg/L 170 136 - 186
Conductivity µmhos/cm 1329 1156-1613
Total Dissolved Solids mg/L 691 544 - 832
Ammonia mg/L 26.0 14.3 - 32.6
Nitrite (as N) mg/L  1.3 0.38 - 3.57
Nitrate (as N) mg/L 0.31 0.15 - 0.61
Total Kjeldahl Nitrogen mg/L 21 12 - 28
Sulfate mg/L 98.2 74.3 - 143
Arsenic µg/L 1.7 < 1.0 - 3.1
Boron
mg/L
0.590 0.465 - 0.748
Chromium
µg/L
1.4
< 1.0 - 1.4
Manganese
µg/L
56.3
45.6 - 69.5
Potassium
mg/L
14.2 11.9 - 18.8
Selenium µg/L < 1.0 N/A
Silica (Total) mg/L 19 15.8 - 21.6
Sodium mg/L 145 126 - 171
Total Coliform Bacteria MPN  < 2* < 2 - 8
 
 
*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.