Houston Water · 90.3% surface water and 9.7% groundwater in the report: San Jacinto River (Lake Conroe/Lake Houston), Trinity River (Lake Livingston), and Evangeline/Chicot aquifers
Houston, TX tap water quality
Houston's tap water scores 52 out of 100 on published data, the low end for a large US system, driven by readings well above health-based guidance. EPA's UCMR 5 monitoring detected PFAS (6:2 FTS 42.6 ppt); lead measured 5.1 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 6 inputs published for this system.
| Measure | Result | Health benchmark | Legal limit | Subscore | Source |
|---|---|---|---|---|---|
| Lead | 5.1 ppb 2025 | 1 | 15 | 71 | Utility report |
| TTHMs | 43.6 ppb | 15 | 80 | 56 | Utility report |
| HAA5 | 40.8 ppb | 15 | 60 | 43 | Utility report |
| Arsenic | 0–6.7 ppb | 1 | 10 | 37 | Utility report |
| Nitrate | 0–1.4 ppm | 5 | 10 | 100 | Utility report |
| PFAS | 6:2 FTS 42.6 ppt | non-detect | any | 25 | EPA UCMR 5 |
Is there PFAS in Houston's water?
Yes. EPA's UCMR 5 monitoring detected PFAS in Houston's system. The compounds and levels recorded were: 6:2 FTS 42.6; PFBA 10.6; PFPeA 6.7; PFHxA 5.1 parts per trillion. For context, EPA's enforceable limits for PFOA and PFOS are 4 ppt each, phased in through 2029; several other compounds have no federal limit yet.
How much lead is in Houston's tap water?
Houston's most recent lead 90th-percentile result is 5.1 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 Houston tap water safe to drink?
Houston's water meets federal legal standards on the measures its utility reports. We score it 52 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 Houston's water been in violation?
EPA's compliance record shows 29 violations for this system, 14 of them health-based, 4 of them since 2020. A health-based violation means a contaminant exceeded a legal limit or required treatment was not delivered. The rules most often cited here: Coliform (TCR) (10), Interim Enhanced Surface Water Treatment Rule (4). Most recent entry: 2019.
Context matters when reading these. Large systems accumulate more violations simply by having more sampling points and more years on record, and a violation from a decade ago says little about water leaving the plant today. What is worth attention is a recent pattern rather than a single old entry.
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 Houston with the rest
Fifty of the largest US systems, scored the same way, every figure cited.