Recycled Water Quality Data
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 2024
| Constituent | Unit | Average | Range |
|---|---|---|---|
| pH | standard unit | 7.1 | 6.8 - 7.36 |
| Total Alkalinity (as CaCO3) | mg/L | 254 | 202 - 314 |
| Bicarbonate (as CaCO3) | mg/L | 254 | 202 - 314 |
| Calcium | mg/L | 54 | 32.8 - 96 |
| Magnesium | mg/L | 26 | 11 - 56 |
| Calcium Hardness (as CaCO3) | mg/L | 136 |
82 - 240 |
| Total Hardness (as CaCO3) | mg/L | 244 | 143 - 464 |
| Chloride | mg/L | 191 | 138 - 230 |
| Conductivity | µmhos/cm | 1314 | 1191 - 1749 |
| Total Dissolved Solids | mg/L | 709 | 604 - 850 |
| Ammonia (as N) | mg/L | 35.4 | 22 - 54 |
| Nitrite (as N) | mg/L | 1.40 | <0.10 -7.7 |
| Nitrate (as N) | mg/L | 0.52 | <0.10 - 2.9 |
| Total Kjeldahl Nitrogen | mg/L | 34 | 20 - 51 |
| Sulfate | mg/L | 161 | 116 - 218 |
| Arsenic | µg/L | 0.56 | <0.5 - 0.58 |
| Boron |
mg/L |
0.52 | 0.42 - 0.76 |
| Chromium |
µg/L |
<2 | N/A |
| Manganese |
µg/L |
58 | <50 - 70 |
| Potassium |
mg/L |
17 | 14 - 20 |
| Selenium | µg/L | 0.55 | <0.5 - 0.8 |
| Silica (Total) | mg/L | 13.6 | 12.3 - 15 |
| Sodium | mg/L | 170 | 160 - 190 |
| Total Coliform Bacteria | MPN/100 ml | <1* | <1 - 67.7 |
| Copper | ug/L | 9.5 | 3.1 - 27 |
| Lead | ug/L | <0.5 | N/A |
| Zinc | ug/L | 20 | <20 - 24 |
*Median
Abbreviations
mg/L = milligrams per liter
µmhos = micromhos per centimeter
µg/L = micrograms per liter
MPN = most probable number
µmhos = micromhos per centimeter
µg/L = micrograms per liter
MPN = most probable number
Suitable Plants for Recycled Water Irrigation
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.