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City & Well

Total Trihalomethanes (TTHM)

Presence of Combined Total Trihalomethanes (TTHM) Contaminants in Tampa Bay Drinking Water

Combined Total Trihalomethanes (TTHM) are a group of chemical contaminants that can form in drinking water during disinfection. TTHMs include chloroform, bromoform, bromodichloromethane, and dibromochloromethane.

TTHMs are prevalent across Florida, as chlorine disinfection is commonly used to treat drinking water supplies. Levels tend to be higher in surface water supplies compared to groundwater. TTHM levels also vary seasonally, with higher levels in warmer months when more disinfection is needed.

TTHM Levels in Tampa Bay Counties and Cities

TTHM contaminants have been detected at some level in all major county and city water supplies in the Tampa Bay region, including:

Hillsborough County

  • Tampa

  • Temple Terrace

  • Plant City

  • Brandon

  • Carrollwood

  • Egypt Lake-Leto

  • FishHawk

  • Gibsonton

  • Keystone

  • Lake Magdalene

  • Lutz

  • Mango

  • Riverview

  • Seffner

  • Thonotosassa

  • Town 'n' Country

  • University

  • Valrico

Pinellas County

  • Clearwater

  • Dunedin

  • Gulfport

  • Largo

  • Oldsmar

  • Pinellas Park

  • Safety Harbor

  • St. Petersburg

  • Tarpon Springs

Pasco County

  • Dade City

  • Lacoochee

  • New Port Richey

  • Port Richey

  • San Antonio

  • Wesley Chapel

  • Zephyrhills

Polk County

  • Auburndale

  • Bartow

  • Davenport

  • Haines City

  • Lake Wales

  • Lakeland

  • Winter Haven

Hernando County

  • Brooksville

  • Spring Hill

  • Weeki Wachee

Health Concerns from TTHM Exposure

While TTHM levels are regulated and controlled, long-term exposure to elevated levels may have health risks. The maximum contaminant level for TTHMs set by the EPA is 0.080 mg/L.

Some potential health effects linked to TTHM exposure include:

  • Increased cancer risk, particularly bladder cancer

  • Liver, kidney, and central nervous system issues

  • Reproductive and developmental effects

Sensitive populations like pregnant women, infants, and young children may be at greater risk from TTHM exposure.

To minimize risk, the EPA mandates that water systems monitor TTHM levels quarterly and ensure they remain below regulatory limits. Public water suppliers are also required to report TTHM testing results to customers annually.

Water Treatment Solutions for Reducing TTHMs

There are several effective water treatment solutions homeowners can use to reduce TTHM levels in their drinking water:

For more information on how water characteristics like the Floridan Aquifer can impact TTHM formation, see our blog.

Learn more about the effects of water contaminants on personal care.

Contact Aqua-Wise Water Treatment Solutions

To have your water tested and receive a customized water treatment recommendation for reducing TTHMs and other contaminants, schedule a free water test today by calling 727-236-7161 or booking online.

Aqua-Wise offers system installations, financing options, and ongoing maintenance plans to provide clean, safe drinking water for your home or business.


EPA - Total Trihalomethanes

MDH - Trihalomethanes in Drinking Water

CDC - Disinfection Byproducts in Drinking Water

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