Water Quality Report · Updated May 12, 2026
CITY OF ROUND ROCK
CITY OF ROUND ROCK delivers tap water graded C (65/100) by TapWaterSafety.org. The utility serves approximately 130,662 residents in ROUND ROCK, Texas using surface water. The most significant water quality concerns are: Haloacetic acids (HAA9) significantly above health guideline; Total trihalomethanes (TTHMs) significantly above health guideline; Bromochloroacetic acid significantly above health guideline. For questions, the utility can be reached at 512-218-5410.
Is ROUND ROCK tap water safe to drink?
CITY OF ROUND ROCK delivers tap water that earns a grade of C (65/100) from TapWaterSafety.org — an average rating, with several contaminants above health guidelines but generally compliant with US legal limits.
The utility serves 130,662 residents in ROUND ROCK, drawing from surface water. Despite being legal under US EPA standards, this water would fail the European Union's Drinking Water Directive, primarily due to haloacetic acids (haa9) significantly above health guideline.
Public testing data identifies 15 contaminants in this water above EWG's health-based guidelines, including: Haloacetic acids (HAA9), Total trihalomethanes (TTHMs), Bromochloroacetic acid, Dibromochloromethane, Dibromoacetic acid, Bromodichloromethane, Haloacetic acids (HAA5), Bromoform, Dichloroacetic acid, Nitrate and nitrite, Chloroform, Radium, combined (-226 and -228), Trichloroacetic acid, Nitrate, Chromium (hexavalent). For most residents, a properly certified home filter at the kitchen tap is the most cost-effective way to reduce exposure to whatever's in your water. See our filter recommendations below, matched specifically to this utility's contaminant profile.
Quick actions for ROUND ROCK residents
Top concerns in this water
Based on the most recent EPA and EWG data, these are the most significant water quality issues for CITY OF ROUND ROCK.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 27.3 ppb, 454x above the EWG health guideline of 0.06 ppb.
Total trihalomethanes (TTHMs) significantly above health guideline
Moderate concernTotal trihalomethanes (TTHMs) detected at 47.9 ppb, 319x above the EWG health guideline of 0.15 ppb.
Bromochloroacetic acid significantly above health guideline
Moderate concernBromochloroacetic acid detected at 4.98 ppb, 249x above the EWG health guideline of 0.02 ppb.
Contact CITY OF ROUND ROCK
Reach the utility directly for service issues, water quality concerns, or to request your Consumer Confidence Report.
General Contact
Treatment Plant
Recommended water filters for ROUND ROCK
Filters matched to the specific contaminants in this water supply.
Carbon block (NSF/ANSI 42 + 53)
$40-$750Activated carbon is highly effective for disinfection byproducts like TTHM and HAA5.
Disclosure: TapWaterSafety earns a commission from purchases made through these links. This does not influence our scoring methodology or filter selection.
Score breakdown
This utility's overall score of 65/100 breaks down across five weighted components. Read the full methodology →
Contaminants detected — international standards comparison
Every contaminant detected, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal (the strictest US benchmark). Why we show multiple standards →
| Contaminant | Detected | EWG US health-based |
EPA US legal |
EU DWD Europe |
WHO global |
CA PHG strictest US |
Tested sample year |
Status |
|---|---|---|---|---|---|---|---|---|
| Haloacetic acids (HAA9) Disinfection byproduct |
27.3 ppb | 0.06 | — | — | — | — | — | 454× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
47.9 ppb | 0.15 | 80.0 | 100 | — | — | — | 319× over |
| Bromochloroacetic acid Disinfection byproduct |
4.98 ppb | 0.02 | — | — | — | — | — | 249× over |
| Dibromochloromethane Disinfection byproduct |
20.3 ppb | 0.1 | — | — | — | — | — | 203× over |
| Dibromoacetic acid Disinfection byproduct |
5.91 ppb | 0.03 | — | — | — | — | — | 197× over |
| Bromodichloromethane Disinfection byproduct |
11.8 ppb | 0.06 | — | — | — | — | — | 196× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
10.3 ppb | 0.1 | 60.0 | 60 | — | — | — | 103× over |
| Bromoform Disinfection byproduct |
9.95 ppb | 0.5 | — | — | — | — | — | 20× over |
| Dichloroacetic acid Disinfection byproduct |
3.28 ppb | 0.2 | — | — | — | — | — | 16× over |
| Nitrate and nitrite Inorganic |
1.8 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 13× over |
| Chloroform Disinfection byproduct |
4.15 ppb | 0.4 | — | — | — | — | — | 10× over |
| Radium, combined (-226 and -228) Radiological |
0.5 pCi/L | 0.05 | 5.0 | — | — | — | — | 10× over |
| Trichloroacetic acid Disinfection byproduct |
0.986 ppb | 0.1 | — | — | — | — | — | 9.9× over |
| Nitrate Inorganic |
0.324 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 2.3× over |
| Chromium (hexavalent) Heavy metal |
0.0394 ppb | 0.02 | — | — | — | — | — | 2.0× over |
| Bromochloromethane Other |
0.0277 ppb | 0.06 | — | — | — | — | — | Below guideline |
| Atrazine Pesticide/Herbicide |
0.0325 ppb | 0.1 | 3.0 | 0.1 | 100 | 0.15 | — | Below guideline |
| Aluminum Heavy metal |
109.1 ppb | 600.0 | — | 200 | — | 600 | — | Below guideline |
| Vanadium Other |
2.22 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Barium Heavy metal |
39.4 ppb | 700.0 | 2000.0 | — | 1300 | 2000 | — | Below guideline |
| Chlorate Disinfection byproduct |
10.6 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Molybdenum Other |
1.83 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Manganese Heavy metal |
0.238 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Monobromoacetic acid Disinfection byproduct |
0.0458 ppb | 25.0 | — | — | — | — | — | Below guideline |
| Monochloroacetic acid Disinfection byproduct |
0.0635 ppb | 53.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.605 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Cyanide Inorganic |
72.5 ppb | — | 200.0 | 50 | 70 | 150 | — | Fails EU |
| Fluoride Inorganic |
0.245 ppm | — | 4.0 | 1.5 | 1.5 | — | — | Below guideline |
| Hexadecanoic acid Other |
3.3 ppb | — | — | — | — | — | — | Below guideline |
| Octadecanoic acid Other |
70.0 ppb | — | — | — | — | — | — | Below guideline |
| Phenol, p-tert-butyl- Other |
3.0 ppb | — | — | — | — | — | — | Below guideline |
All values in the unit of the detected level. Red cells indicate the detected level exceeds that standard. Some contaminants have limits in some jurisdictions but not others (shown as —). The "Tested" column shows the year each contaminant sample was collected.
Sources: US EPA, EU Drinking Water Directive 2020/2184, WHO Guidelines (4th ed.), California OEHHA PHGs, EWG Tap Water Database.
CITY OF ROUND ROCK service area
This water system serves 1 community in Williamson County, Texas. Click any city for its dedicated tap water quality page.
Find the right filter for ROUND ROCK water
Browse filter categories by water-quality concern. Each option below is NSF-certified for the matched contaminant type.