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TheH2O Standard

City of Houston · serves 2,202,531 people

Tap Water Quality in Houston, TX 77002

City of Houston's own testing found 14 contaminants above EWG's health guidelines, led by Haloacetic acids (HAA9) at 599x, Arsenic at 516x, Bromochloroacetic acid at 229x. Here's every one, what it does, and what takes it out.

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The numbers

Above EWG health guidelines

14

contaminants

Other contaminants detected

37

under the guideline

Tested for, not found

189

chemicals

People served

2,202,531

City of Houston

Met federal legal limits in the latest quarter the EPA assessed (April 2024 - June 2024). Legal doesn't mean the water meets today's health guidelines: most legal limits haven't moved in about 20 years, and many of these chemicals have none. Harris County, TX.

Contaminants Above EWG's Health Guidelines

Detected in 2021-2023 at annual averages over the level a public health authority considers safe. Most have no legal limit at all.

  • Haloacetic acids (HAA9)

    cancer

    599xEWG guideline

    This utility
    36.0 ppb
    EWG guideline
    0.06 ppb
    Legal limit
    None
    • Activated carbon
    • Reverse osmosis

    State avg 23.9 ppb · US avg 23.7 ppb

    What is this contaminant?

    Haloacetic acids are formed when disinfectants such as chlorine are added to tap water. The group of nine haloacetic acids includes monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid and dibromoacetic acid, which are regulated as a group by the federal government (HAA5); and bromochloroacetic acid, bromodichloroacetic acid, chlorodibromoacetic acid, and tribromoacetic acid.

    Where it comes from: treatment byproducts.

  • Arsenic

    cancer

    516xEWG guideline

    This utility
    2.06 ppb
    EWG guideline
    0.004 ppb
    Legal limit
    10 ppb
    • Ion exchange
    • Reverse osmosis

    State avg 0.942 ppb · US avg 0.624 ppb

    What is this contaminant?

    Arsenic is a potent carcinogen and common contaminant in drinking water. Arsenic causes thousands of cases of cancer each year in the U.S. Click here to read more about arsenic.

    Where it comes from: agriculture, industry, naturally occurring.

  • Bromochloroacetic acid

    229xEWG guideline

    This utility
    4.57 ppb
    EWG guideline
    0.02 ppb
    Legal limit
    None
    • Activated carbon
    • Reverse osmosis

    State avg 3.82 ppb · US avg 2.8 ppb

    What is this contaminant?

    Bromochloroacetic acid is formed when chlorine or other disinfectants are used to treat drinking water. Bromochloroacetic acid and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy.

    Where it comes from: treatment byproducts.

  • Haloacetic acids (HAA5)

    cancer

    212xEWG guideline

    This utility
    21.2 ppb
    EWG guideline
    0.1 ppb
    Legal limit
    60 ppb
    • Activated carbon
    • Reverse osmosis

    State avg 12.5 ppb · US avg 19.8 ppb

    What is this contaminant?

    Haloacetic acids are formed when disinfectants such as chlorine are added to tap water. The group of five haloacetic acids regulated by federal standards includes monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid and dibromoacetic acid.

    Where it comes from: treatment byproducts.

  • Total trihalomethanes (TTHMs)

    cancer

    203xEWG guideline

    This utility
    30.4 ppb
    EWG guideline
    0.15 ppb
    Legal limit
    80 ppb
    • Activated carbon
    • Reverse osmosis

    State avg 25.6 ppb · US avg 29.1 ppb

    What is this contaminant?

    Trihalomethanes are cancer-causing contaminants that form during water treatment with chlorine and other disinfectants. The total trihalomethanes group includes four chemicals: chloroform, bromodichloromethane, dibromochloromethane and bromoform.

    Where it comes from: treatment byproducts.

  • Bromodichloromethane

    cancer

    103xEWG guideline

    This utility
    6.19 ppb
    EWG guideline
    0.06 ppb
    Legal limit
    None
    • Activated carbon
    • Reverse osmosis

    State avg 6.5 ppb · US avg 5.89 ppb

    What is this contaminant?

    Bromodichloromethane, one of the total trihalomethanes (TTHMs), is formed when chlorine or other disinfectants are used to treat drinking water. Bromodichloromethane and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.

    Where it comes from: treatment byproducts.

  • Dichloroacetic acid

    cancer

    76xEWG guideline

    This utility
    15.1 ppb
    EWG guideline
    0.2 ppb
    Legal limit
    None
    • Activated carbon
    • Reverse osmosis

    State avg 6.77 ppb · US avg 8 ppb

    What is this contaminant?

    Dichloroacetic acid, one of the group of five haloacetic acids regulated by federal standards, is formed when chlorine or other disinfectants are used to treat drinking water. Haloacetic acids and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.

    Where it comes from: treatment byproducts.

  • Trichloroacetic acid

    cancer

    45xEWG guideline

    This utility
    4.54 ppb
    EWG guideline
    0.1 ppb
    Legal limit
    None
    • Activated carbon
    • Reverse osmosis

    State avg 2.14 ppb · US avg 6.57 ppb

    What is this contaminant?

    Trichloroacetic acid, one of the group of five haloacetic acids regulated by federal standards, is formed when chlorine or other disinfectants are used to treat drinking water. Haloacetic acids and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.

    Where it comes from: treatment byproducts.

  • Chromium (hexavalent)

    cancer

    37xEWG guideline

    This utility
    0.747 ppb
    EWG guideline
    0.02 ppb
    Legal limit
    None
    • Ion exchange
    • Reverse osmosis

    State avg 0.32 ppb · US avg 0.44 ppb

    What is this contaminant?

    Chromium (hexavalent) is a carcinogen that commonly contaminates American drinking water. Chromium (hexavalent) in drinking water may be due to industrial pollution or natural occurrences in mineral deposits and groundwater. Read more about chromium (hexavalent).

    Where it comes from: industry, naturally occurring.

  • Chloroform

    cancer

    34xEWG guideline

    This utility
    13.7 ppb
    EWG guideline
    0.4 ppb
    Legal limit
    None
    • Activated carbon
    • Reverse osmosis

    State avg 7.52 ppb · US avg 16.2 ppb

    What is this contaminant?

    Chloroform, one of the total trihalomethanes (TTHMs), is formed when chlorine or other disinfectants are used to treat drinking water. Chloroform and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy.

    Where it comes from: treatment byproducts.

  • Dibromoacetic acid

    32xEWG guideline

    This utility
    0.970 ppb
    EWG guideline
    0.03 ppb
    Legal limit
    None
    • Activated carbon
    • Reverse osmosis

    State avg 2.64 ppb · US avg 1.13 ppb

    What is this contaminant?

    Dibromoacetic acid, one of the group of five haloacetic acids regulated by federal standards, is formed when chlorine or other disinfectants are used to treat drinking water. Haloacetic acids and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.

    Where it comes from: treatment byproducts.

  • Dibromochloromethane

    cancer

    20xEWG guideline

    This utility
    2.01 ppb
    EWG guideline
    0.1 ppb
    Legal limit
    None
    • Activated carbon
    • Reverse osmosis

    State avg 5.95 ppb · US avg 3.55 ppb

    What is this contaminant?

    Dibromochloromethane, one of the total trihalomethanes (TTHMs), is formed when chlorine or other disinfectants are used to treat drinking water. Dibromochloromethane and other disinfection byproducts increase the risk of cancer and may cause problems during pregnancy. Click here to read more about disinfection byproducts.

    Where it comes from: treatment byproducts.

  • Radium, combined (-226 and -228)

    cancer

    17xEWG guideline

    This utility
    0.85 pCi/L
    EWG guideline
    0.05 pCi/L
    Legal limit
    5 pCi/L
    • Ion exchange
    • Reverse osmosis

    State avg 0.37 pCi/L · US avg 0.33 pCi/L

    What is this contaminant?

    Radium is a radioactive element that causes bone cancer and other cancers. It can occur naturally in groundwater, and oil and gas extraction activities such as hydraulic fracturing can elevate concentrations.

    Where it comes from: industry, naturally occurring.

  • Uranium

    cancer

    5.1xEWG guideline

    This utility
    2.19 pCi/L
    EWG guideline
    0.43 pCi/L
    Legal limit
    20 pCi/L
    • Ion exchange
    • Reverse osmosis

    State avg 0.62 pCi/L · US avg 1.03 pCi/L

    What is this contaminant?

    Uranium is a known human carcinogen. The federal legal limit for uranium is set at 30 micrograms per liter (corresponding to parts per billion), but utilities can also report uranium in picocuries per liter (pCi/L), which is a measure of radioactivity in water. EWG translated all uranium results to pCi/L using a conversion factor developed by the EPA. With this conversion approach, the limit of 30 ppb corresponds to 20 pCi/L. Drinking water with this much uranium would cause more than 4.6 cancer cases in a population of 100,000. California set a public health goal for uranium of 0.43 pCi/L.

    Where it comes from: industry, naturally occurring.

What Takes It Out

EWG lists which home filter technologies reduce each contaminant. Counted against this utility's report:

Reverse osmosis

14 of 14

contaminants above the guideline, plus 33 other detected. Reverse osmosis is the drinking water system under the sink.

Reverse Osmosis

Activated carbon

10 of 14

contaminants above the guideline, plus 20 other detected. Activated carbon is the whole-house filter on the main line.

Whole-House Filtration

Ion exchange

4 of 14

contaminants above the guideline. Ion exchange is what a water softener does; it also takes out the hardness that scales your fixtures.

Water Softeners

A complete system stacks all three: carbon on the main line, a softener, and reverse osmosis at the kitchen sink. One flat price, installed by a licensed plumber near you.

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Other Contaminants Detected

Found in the water, under EWG's guideline. Shown as a share of the guideline so you can see what's close.

ContaminantThis utilityOf the guidelineLegal limitWhat filters it
6:2 Fluorotelomer Sulfonic Acid (6:2 FTSA)1.69 ppt
100% of 1 ppt
NoneActivated carbon, Reverse osmosis
Atrazine0.104 ppb
100% of 0.1 ppb
3 ppbActivated carbon, Reverse osmosis
Nitrate0.155 ppm
100% of 0.14 ppm
10 ppmIon exchange, Reverse osmosis
Bromoform0.204 ppb
41% of 0.5 ppb
NoneActivated carbon, Reverse osmosis
Simazine0.0294 ppb
29% of 0.1 ppb
4 ppbActivated carbon, Reverse osmosis
Barium158.8 ppb
23% of 700 ppb
2,000 ppbIon exchange, Reverse osmosis
Aluminum101.9 ppb
17% of 600 ppb
NoneReverse osmosis
Chlorate31.3 ppb
15% of 210 ppb
NoneActivated carbon, Reverse osmosis, Ion exchange
Cyanide22.1 ppb
11% of the legal limit
200 ppbIon exchange, Reverse osmosis
Vanadium1.91 ppb
9% of 21 ppb
NoneIon exchange
Manganese7.29 ppb
7% of 100 ppb
NoneIon exchange
Fluoride0.264 ppm
7% of the legal limit
4 ppmReverse osmosis
Molybdenum1.99 ppb
5% of 40 ppb
NoneIon exchange, Reverse osmosis
Thallium0.00483 ppb
5% of 0.1 ppb
2 ppbIon exchange, Reverse osmosis
Selenium1.28 ppb
4% of 30 ppb
50 ppbReverse osmosis
Di(2-ethylhexyl) phthalate0.0822 ppb
3% of 3 ppb
6 ppbActivated carbon, Reverse osmosis
1,4-Dioxane0.00599 ppb
2% of 0.35 ppb
NoneReverse osmosis
Monochloroacetic acid0.573 ppb
1% of 53 ppb
NoneActivated carbon, Reverse osmosis
Bromochloromethane0.000363 ppb
1% of 0.06 ppb
NoneActivated carbon, Reverse osmosis
Perfluorobutanoic Acid (PFBA)0.685 ppt
0% of 1,000 ppt
NoneActivated carbon, Reverse osmosis
Perfluorohexanoic Acid (PFHxA)0.632 ppt
0% of 1,000 ppt
NoneActivated carbon, Reverse osmosis
Perfluoropentanoic Acid (PFPeA)0.472 ppt
0% of 1,000 ppt
NoneActivated carbon, Reverse osmosis
Strontium0.361 ppb
0% of 1,500 ppb
NoneIon exchange, Reverse osmosis
Cobalt0.0106 ppb
0% of 70 ppb
NoneIon exchange, Reverse osmosis
Toluene0.0134 ppb
0% of 150 ppb
1,000 ppbActivated carbon, Reverse osmosis
Xylenes (total)0.130 ppb
0% of 1,800 ppb
10,000 ppbActivated carbon, Reverse osmosis
Ethylbenzene0.0152 ppb
0% of 300 ppb
700 ppbActivated carbon, Reverse osmosis
Picloram0.00476 ppb
0% of 166 ppb
500 ppbActivated carbon, Reverse osmosis
2-methyl-1-propene3.50 ppb
No guideline
NoneActivated carbon, Reverse osmosis
Erucylamide3.00 ppb
No guideline
NoneActivated carbon, Reverse osmosis, Ion exchange
Germanium0.115 ppb
No guideline
NoneReverse osmosis
Hexadecanoic acid15.3 ppb
No guideline
NoneActivated carbon, Reverse osmosis
Lithium12.0 ppb
No guideline
NoneIon exchange, Reverse osmosis
Methyl isobutyl ketone0.0777 ppb
No guideline
NoneActivated carbon, Reverse osmosis
o-toluidine0.00120 ppb
No guideline
NoneActivated carbon, Reverse osmosis
Octadecanoic acid32.8 ppb
No guideline
NoneActivated carbon, Reverse osmosis
Oleic acid3.20 ppb
No guideline
NoneActivated carbon, Reverse osmosis
189 chemicals tested for and not foundShow the list

1,1,1,2-Tetrachloroethane, 1,1,1-Trichloroethane, 1,1,2,2-Tetrachloroethane, 1,1,2-Trichloroethane, 1,1-Dichloroethane, 1,1-Dichloroethylene, 1,1-Dichloropropene, 1,2,3-Trichlorobenzene, 1,2,3-Trichloropropane, 1,2,4-Trichlorobenzene, 1,2,4-Trimethylbenzene, 1,2-Dibromo-3-chloropropane (DBCP), 1,2-Dichloroethane, 1,2-Dichloropropane, 1,3,5-Trimethylbenzene, 1,3-Butadiene, 1,3-Dichloropropane, 1-butanol, 11-chloroeicosafluoro-3-oxaundecane-1-sulfonic aci, 17-beta-Estradiol, 2,2-Dichloropropane, 2,3-Dichlorobiphenyl, 2,4,5-T, 2,4,5-TP (Silvex), 2,4,5-Trichlorobiphenyl, 2,4-D, 2,4-DB, 2-Chlorobiphenyl, 2-Hexanone, 2-methoxyethanol, 2-propen-1-ol, 22'3'46-Pentachlorobiphenyl, 22'33'44'6-Heptachlorobiphenyl, 22'33'45'66'-Octachlorobiphenyl, 22'44'-Tetrachlorobiphenyl, 22'44'56'-Hexachlorobiphenyl, 3,5-Dichlorobenzoic acid, 3-Hydroxycarbofuran, 4,8-dioxa-3H-perfluorononanoic acid (ADONA), 4-Androstene-3,17-dione, 4:2 Fluorotelomer Sulfonic Acid (4:2 FTSA), 8:2 Fluorotelomer Sulfonic Acid (8:2 FTSA), 9-chlorohexadecafluoro-3-oxanone-1-sulfonic acid (, Acenaphthene, Acenaphthylene, Acetone, Acifluorfen (Blazer), Acrylonitrile, Alachlor (Lasso), Aldicarb, Aldicarb sulfone, Aldicarb sulfoxide, Aldrin, alpha-Chlordane, Alpha-hexachlorocyclohexane, Anthracene, Antimony, Asbestos, Baygon (Propoxur), Bentazon (Basagran), Benzene, Benzo[a]anthracene, Benzo[b]fluoranthene, Benzo[g,h,i]perylene, Benzo[k]fluoranthene, Beryllium, Bromacil, Bromobenzene, Bromomethane, Butachlor, Butanoic acid, 2,2,3,3,4,4-hexafluoro-4-(trifluoro, Butyl benzyl phthalate, Butylated hydroxyanisole, Cadmium, Carbaryl, Carbofuran, Carbon tetrachloride, Chloramben, Chlordane, Chlorodifluoromethane, Chloroethane, Chloromethane, Chlorpyriphos, Chrysene, cis-1,2-Dichloroethylene, cis-1,3-Dichloropropene, Dalapon, Di(2-ethylhexyl) adipate, Di-n-butyl phthalate, Dibenz[a,h]anthracene, Dibromomethane, Dicamba, Dichlorodifluoromethane, Dichloromethane (methylene chloride), Dichlorprop, Dieldrin, Diethyl phthalate, Dimethipin, Dimethyl phthalate, Dinoseb, Endrin, Equilin, Estriol, Estrone, Ethinyl estradiol, Ethoprop, Ethyl methacrylate, Ethylene dibromide, Fluorene, gamma-Chlordane, Heptachlor, Heptachlor epoxide, Hexachlorobenzene (HCB), Hexachlorobutadiene, Hexachlorocyclopentadiene, Hexafluoropropylene oxide dimer acid (HFPO-DA), Indeno[1,2,3-cd]pyrene, Iodomethane, Isopropylbenzene, Lindane, m-Dichlorobenzene, Mercury (inorganic), Methiocarb, Methomyl, Methoxychlor, Methyl ethyl ketone, Methyl methacrylate, Metolachlor, Metribuzin, Monobromoacetic acid, Monochlorobenzene (chlorobenzene), MTBE, n-Butylbenzene, N-ethyl perfluorooctane sulfonamido acetic acid (N, N-methyl perfluorooctanesulfonamidoacetic acid, n-Propylbenzene, Naphthalene, Nitrite, Nonafluoro-3,6-dioxaheptanoic acid, o-Chlorotoluene, o-Dichlorobenzene, Oxamyl (Vydate), Oxyflurofen, p-Chlorotoluene, p-Dichlorobenzene, p-Isopropyltoluene, Pentachlorophenol, Perfluoro(2-ethoxyethane)sulfonic acid, Perfluorobutane sulfonate (PFBS), Perfluorodecanoic acid (PFDA), Perfluorododecanoic acid (PFDoA), Perfluoroheptane sulfonic acid (PFHpS), Perfluoroheptanoic acid (PFHPA), Perfluorohexane sulfonate (PFHXS), Perfluorononanoic acid (PFNA), Perfluorooctane sulfonate (PFOS), Perfluorooctanoic acid (PFOA), Perfluoropentane sulfonic acid (PFPeS), Perfluorotetradecanoic acid (PFTA), Perfluorotridecanoic acid (PFTrDA), Perfluoroundecanoic acid (PFUnA), Permethrin, Phenanthrene, Polychlorinated biphenyls (PCBs), Profenofos, Propachlor, Propanoic acid, 2,2,3,3-tetrafluoro-3-(trifluorome, Pyrene, Quinclorac, Quinoline, sec-Butylbenzene, Silver, Styrene, Tebuconazole, tert-Butylbenzene, Testosterone, Tetrachloroethylene (perchloroethylene), Tetrahydrofuran, Toxaphene, trans-1,2-Dichloroethylene, trans-1,2-Dichloropropene, trans-1,3-Dichloropropene, trans-Nonachlor, Tribufos, Trichloroethylene, Trichlorofluoromethane, Trifluralin, Vinyl acetate, Vinyl chloride.

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We install in Houston. Water softener installation in Houston, TX

Source: the EWG Tap Water Database, built from City of Houston's own testing in 2021-2023, as reported to the state and the EPA. Legal limits are federal (or state) maximums; health guidelines are the levels EWG's scientists consider protective, usually set by a state or federal public health authority. “Times over” compares the utility's annual average with the guideline. Last pulled October 2026.Hardness isn't in EWG's data; ours is an area estimate.

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Your utility's own test results, from the EWG Tap Water Database: what's in the water, how it compares with health guidelines, and what takes it out.

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