HomeMy WebLinkAbout05. Recycled Water Quality (Salinity Content)5
Central Contra Costa Sanitary District
July 9, 2014
TO: REAL ESTATE, ENVIRONMENTAL & PLANNING (REEP) COMMITTEE
FROM: MELODY LABELLA, PROVISIONAL ASSOCIATE ENGINEER *Gk
SUBJECT: SALINITY CONTENT OF RECYCLED WATER
At the June 19, 2014, Central Contra Costa Sanitary District (District) Board meeting,
Board member McGill requested an item be added on the salt content in the District's
recycled water for our next REEP Committee meeting agenda.
The quality of recycled water depends on the source water and level of treatment.
Generally recycled water will have a higher concentration of dissolved salts than
drinking water. Water with high levels of salts can have adverse effects on plant health
and appearance; however, most recycled water produced does not have harmful levels
of salts for most plants. Recycled water supplies, by their nature, have higher salinity
content, so it should always be a consideration in managing landscapes irrigated with
recycled water. In our recycled water service area, the winter rains have typically been
adequate to flush any accumulated salts from the previous irrigation season. However,
soil type can have a major influence on this process.
Since total dissolved solids (TDS) typically represents the dissolved salts in a water
supply, it is used as a surrogate to compare salinity content. The following TDS
information is provided as background information and staff will discuss this issue
further in your Committee meeting on July 14, 2014.
Table 1. Comparison of Water Quality Supplies in California
Supplier
TDS (mg /L)*
Contra Costa Water District — Raw Delta Water
200-350
Central Contra Costa Sanitary District
450-550
Southern California Potable Water
550-600
City of Petaluma
576
West County Wastewater District
590
Dublin San Ramon Services District
597
EBMUD
634 -870
Daly City
700
South Bay Water Recycling
733
Carmel Area Wastewater District
823
Delta Diablo
960
Carmel Valley- California American Water
1,200 — 1,800
*The TDS data presented is from different years. Depending on the water source,
water year and other factors, TDS can vary seasonally and even annually.