Your water is regularly tested for more than 120 chemicals and other substances, as well as radioactivity. The table below provides detailed information about the water that comes from your tap after it is treated (treated water) and before it is treated (raw water). The substances shown are ones that our customers have the most questions about.
You can also view the latest Annual Water Quality Report, which lists the annual results for these substances as well as many others.
Questions? Call our Water Quality Hotline at 925-688-8156 or email us.
Recent Water Quality Results
Substance
Maximum Contaminant Level*
Most Recent Result
Date
Source
Arsenic
0.01 mg/L
< 0.001 mg/L
7/11/2017
BCWO annual
Chloride
No MCL (65 mg/L CCWD Internal Action Level)
63 mg/L
5/15/2018
BCWO
Chlorine Residual
4.0 mg/L
3.5 mg/L
5/29/2018
BCWO
Mercury
0.002 mg/L
<0.00020 mg/L
7/11/2017
R/BCWO annual
Radon **
300 pci/L
<100pci/L
1/2016
Mallard Res; triennial
Total Coliforms
>5% positive
0% positive
5/2018
Last DDW report
Hardness
No MCL
86 mg/L
5/15/2018
BCWO
Hardness
No MCL
6.0 grains/gallon
5/15/2018
BCWO
*Maximum Contaminant Level (MCL): The highest level of a contaminant that is allowed in drinking water based on health risk coupled with economic and technical feasibility for control/treatment.