Modesto
Modesto, CA water profile — supply sources, drought status, wastewater reuse, and the key water issues facing the city.
modesto, city of
surface water (rivers/reservoirs) · local government · PWSID CA5010010
Below EPA's 15 ppb lead action level at last testing.
Source: EPA Safe Drinking Water Information System (SDWIS) · 2026 Q1
Modesto is a mid-sized city and the 18th-largest in California, home to roughly 211,266 residents. Modesto's drinking water comes largely from the same regional sources that serve California: Sierra snowpack, Colorado River, State Water Project, and groundwater.
As elsewhere in California, the central challenge is drought. Orange County runs the world's largest groundwater replenishment system, and the state adopted direct potable reuse rules in 2023 — but the Central Valley's groundwater overdraft remains severe.
California reuses an estimated 23% of its treated wastewater and maintains established reuse programs; Modesto tracks abnormally dry to moderate drought conditions on the U.S. Drought Monitor scale.
Explore the California profile for statewide context, or dig into the water issues shaping Modesto below.
Stanislaus County water quality
Source: EPA SDWIS · 2026 Q1
At a glance
- Population ~211,266 (18th-largest in California)
- Primary sources: Sierra snowpack, Colorado River, State Water Project, and groundwater
- Drought: abnormally dry to moderate conditions
- State reuse rate: ~23% of wastewater
Statewide drought history
% of California in severe+ drought (Moderate (D1) now).
Source: U.S. Drought Monitor
Common questions
Is tap water safe in Modesto?
Modesto's largest water system, MODESTO, CITY OF, serves about 218,771 people. EPA records show 0 health-based violation(s) since 2016 and a most-recent 90th-percentile lead level of 12 ppb (EPA action level is 15 ppb). Always check your own provider's annual Consumer Confidence Report.
Where does Modesto get its water?
MODESTO, CITY OF draws primarily from surface water (rivers/reservoirs), part of California's supply from Sierra snowpack, Colorado River, State Water Project.
Related water issues
Drought
Much of the American West is in a multi-decade dry period that researchers describe as the most severe in over a millennium, reshaping how communities plan for water.
ExploreColorado River
The river that supplies 40 million people has lost roughly a fifth of its flow since 2000, forcing a renegotiation of how seven states share the water.
ExploreGroundwater Depletion
Aquifers from the Central Valley to the Ogallala are being pumped faster than they recharge, causing land subsidence and threatening long-term supply.
ExplorePotable Reuse
Advanced purification turns treated wastewater into water that meets or exceeds drinking-water standards — increasingly essential in water-stressed regions.
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