Microbial
Giardia lamblia in U.S. tap water
48 public water systems across 9 U.S. states report Giardia lamblia in their annual Consumer Confidence Report. None currently sit at or above the federal limit.
Within the federal limit (15)
| Water system | Measured |
|---|---|
| Beverly Hills-city, Water Dept. — Beverly Hills, Ca, CA 2020 annual report | Not detected |
| Beverly Hills-city, Water Dept. — Beverly Hills, Ca, CA 2021 annual report | Not detected |
| Columbus, OH 2025 annual report | Not detected |
| Foothill Municipal Water Dist. — La Canada Flintridge, Ca, CA 2020 annual report | Not detected |
| Foothill Municipal Water Dist. — La Canada Flintridge, Ca, CA 2022 annual report | Not detected |
| Foothill Municipal Water Dist. — La Canada Flintridge, Ca, CA 2021 annual report | Not detected |
| Frisco, TX 2024 annual report | Not detected |
| Garland, TX 2024 annual report | 0–0 |
| Grand Rapids, MI 2025 annual report | Not detected |
| Lomita-city, Water Dept. — Lomita, Ca, CA 2023 annual report | Not detected |
| Lomita-city, Water Dept. — Lomita, Ca, CA 2022 annual report | Not detected |
| Plano, TX 2024 annual report | 0 |
| Pomona, CA 2024 annual report | Not detected |
| Three Valleys MWD — Claremont, Ca, CA 2023 annual report | Not detected |
| Wichita Falls, TX 2024 annual report | 0 |
Frequently asked
+What is Giardia lamblia?
Giardia lamblia is a contaminant some U.S. public water utilities measure and report in their annual Consumer Confidence Report.
+What is the federal limit for Giardia lamblia in drinking water?
The federal Public health goal for Giardia lamblia is 0 . The EPA enforces this against the regulated reporting statistic (typically a running annual average or 90th percentile), not a single-sample spike.
+How many U.S. water systems have Giardia lamblia over the federal limit?
Zero of the 48 public water systems in The Water Map dataset currently report Giardia lamblia at or above its federal limit.
+How can I check if Giardia lamblia is in my city's tap water?
Search your city on The Water Map (https://www.thewatermap.com/) or browse the list on this page. Every U.S. public water utility is required to publish an annual Consumer Confidence Report that lists every contaminant it measured, including Giardia lamblia.