Great Lakes Water Authority · Great Lakes surface water supplied and treated by GLWA
Detroit, MI tap water quality
Detroit's tap water scores 58 out of 100 on published data, the low end for a large US system, driven by readings well above health-based guidance. Lead measured 8 ppb at the 90th percentile against a 15 ppb action level.
Every figure, with its benchmark
Subscores run from 100 at the health benchmark to 0 at the legal limit. The city score is the weighted average of the 4 inputs published for this system.
| Measure | Result | Health benchmark | Legal limit | Subscore | Source |
|---|---|---|---|---|---|
| Lead | 8 ppb 2025 | 1 | 15 | 50 | Utility report |
| TTHMs | 51.8 ppb | 15 | 80 | 43 | Utility report |
| HAA5 | 20.3 ppb | 15 | 60 | 88 | Utility report |
| Nitrate | 0.35 ppm | 5 | 10 | 100 | Utility report |
Is there PFAS in Detroit's water?
We don't know. Detroit's system has no UCMR 5 record in EPA's 2026 Q2 snapshot, and no testing is not the same as no PFAS. We won't state a result the data doesn't support.
How much lead is in Detroit's tap water?
Detroit's most recent lead 90th-percentile result is 8 ppb. That means nine in ten sampled homes measured at or below that level, and it is a summary figure, not the maximum any single household saw. The federal action level is 15 ppb, but that is a trigger for utility action, not a health threshold: no level of lead exposure is considered safe (EPA, CDC), and lead almost always enters through household plumbing and service lines rather than the treatment plant.
Is Detroit tap water safe to drink?
Detroit's water meets federal legal standards on the measures its utility reports. We score it 58 out of 100 against health-based guidance, which is stricter than the legal minimum by design. Those are two different questions, and most coverage collapses them: a supply can be entirely lawful and still carry readings above the level health researchers would prefer. This score answers the second question, and the table above shows exactly which measure moved it.
Has Detroit's water been in violation?
We found no Safe Drinking Water Act violation records for this system in EPA's compliance data. That is a clean record on the federal register, though absence of a violation is not the same as absence of a contaminant: a system can stay within every legal limit and still carry readings above health-based guidance, which is exactly what the score above measures.
What can you do about it?
If lead is the concern here, the fix is almost never the treatment plant: it's the service line and the plumbing inside the building. Running the tap for thirty seconds after long stagnation, using cold water for drinking and cooking, and asking your utility whether your address has a lead service line are all free. A filter certified to NSF/ANSI 53 for lead is the next step. If PFAS is the concern, NSF/ANSI 53 does not cover it: look for NSF/ANSI 58 reverse osmosis or a filter specifically certified under NSF/ANSI 53 for PFOA and PFOS reduction.
Compare Detroit with the rest
Fifty of the largest US systems, scored the same way, every figure cited.