Largest public system
- City of Concord: TTHM (disinfection byproducts)
- 62.8 ppb
- As reported (2025); federal limit 80 ppb.
- City of Concord, 2025
- City of Concord: HAA5 (disinfection byproducts)
- 47.7 ppb
- As reported (2025); federal limit 60 ppb.
- City of Concord, 2025
- City of Concord: Lead (at sampled homes' taps)
- Not detected
- Not detected (2025); 0 sampled homes above the action level. The federal action level is 15 ppb.
- City of Concord, 2025