Tap water in Walnut, CA — ZIP 91789
3 public water systems serving about 328,028 people. PFAS "forever chemicals" have been detected here.
C
Fair
PFAS detected: at least one system serving this ZIP reported PFAS in EPA UCMR 5
testing. Levels and the 2024 federal limits are shown per system below.
Water systems serving 91789
Suburban Water Systems-San Jose
PWSID CA1910205 · serves 170,523 ·
surface water
0 health-based / 1 total violations (5 yrs)
· PFAS up to 6.2 ppt
Walnut Valley Water District
PWSID CA1910234 · serves 100,941 ·
surface water
0 health-based / 0 total violations (5 yrs)
Gswc-San Dimas
PWSID CA1910142 · serves 56,564 ·
surface water
0 health-based / 0 total violations (5 yrs)
· PFAS up to 20 ppt — above federal limit
Grades summarize EPA SDWIS violation records (last 5 years) and UCMR 5 PFAS results. They are informational, not a health determination. Methodology