Fluoride FAQs

A city ordinance approved by San Antonio voters on Nov. 7, 2000, directed all direct drinking water suppliers serving properties within the city limits to fluoridate all water in their distribution systems.

SAWS complies with the 2000 city ordinance and adds fluoride to all water within its system.

SAWS and the former Bexar Metropolitan Water District (now part of SAWS) started adding fluoride to our distribution systems in August 2002.

Hydrofluorosilicic acid (H2SiF6) is used. The fluoride meets standards set by the American Water Works Association (AWWA) and the National Sanitation Foundation (NSF), organizations that set standards for potable, or drinkable, water.

Fluoride is added to the water at each of our water pump stations. Fluoride at each station is stored in bulk storage tanks. Fluoride is manually transferred from the bulk tanks to smaller day tanks each day to meet pumping requirements. Metering pumps then move the fluoride from day tanks to the water as it is pumped from the well. Fluoride injection pumps operate only when water wells are operating.

Fluoride already occurs naturally in San Antonio’s water at 0.3 parts per million. SAWS adds enough fluoride to bring the fluoride level up to 0.7 parts per million, the recommended level that experts say is necessary to protect teeth against decay. Water from the Trinity Aquifer is naturally fluoridated at near the recommended levels and therefore requires no additional fluoride. Learn more about our Trinity Aquifer water supply.

In 2011, SAWS fluoridated 55.4 billion gallons of water at a cost of $572,880. That works out to 1 cent per 1,000 gallons.

Multiple levels of checks and double-checks are included in the fluoride system, including:

  • Fail-safe devices and procedures at the injection sites.
  • Calibrated measuring devices used in injection pumps.
  • Daily testing by SAWS technicians.
  • Verification of usage amount at site by weight.

Customers can purchase reverse osmosis filtration systems that can remove fluoride from the water. Reverse osmosis is a very high level of filtration that removes up to 98% of dissolved minerals — including chlorine and fluoride — as well as virtually 100% of colloidal and suspended matter. Reverse osmosis filters are available in under-sink models.