Orange City has just been notified that its drinking water violated quality standards during 2018. The culprit? Byproducts of water disinfection called total trihalomethanes, or TTHMs.

Chlorine is both the hero and the villain of water quality in the United States. Water here is treated with disinfectants — commonly chlorine — to remove contaminants, like E. coli or salmonella, that could make a person seriously ill. But the byproduct of chlorine reacting with water that contains organic materials is TTHMs, a group of four chemicals.

Of the four, the one most people would recognize — and the one that is most often the largest portion of TTHMs — is chloroform. For regulatory purposes, the four chemicals are considered one combined contaminant.

The allowable limit of TTHMs in drinking water, set by the federal Environmental Protection Agency, is 80 parts per billion (ppb). Orange City’s water exceeded that limit in one quarter of 2018 at one site, according to drinking-water quality reports, which are published annually by cities and counties around this time of year.

Water-production sites are tested quarterly. Those tests showed that during parts of 2017 and 2018, the average at the 1038 W. French Ave. site was 80.7 ppb.

To conceptualize 80 ppb, one could think of 80 drops of water in an Olympic-size swimming pool. That’s enough to trigger a response from government regulators, but not likely to cause noticeable health effects for the average person, according to the Florida Department of Health.

The Environmental Protection Agency somewhat terrifyingly warns that, over time, TTHMs may cause kidney disease, nervous-system problems, and increased risk of cancer. However, according to the Florida Department of Health, that would be a “slight risk … after decades of drinking water with TTHMs above 80 parts per billion.”

Orange City, home to Blue Spring State Park and its pristine spring, has a history of high-quality water. At the St. Louis World’s Fair in 1904, Orange City’s water got “the highest award the world can give.” For decades, the city maintained a public fountain where visitors regularly stopped to fill up on Orange City water.

Although the limit for TTHMs is 80 ppb, the goal, according to state and federal guidelines, is between 0 ppb and 70 ppb.

Most cities locally, and nationally, are within this range. At most testing sites during 2018, Orange City was, too.

In 2018, DeLand had an overall TTHM level of 58 ppb. In 2017, Lake Helen reported 62, and Deltona had 60.

In October 2015, Lake Helen had a quarter where TTHMs exceeded guidelines.

When that happens, it automatically triggers greater oversight by state agencies, primarily the Florida Department of Health.

“Average” TTHM levels are calculated by averaging the test results for four quarters. If a city has a level of more than 80 ppb at a testing site, the Department of Health sends a “Compliance Assistance Offer” in the form of a letter, the city must issue a public notice, and the city’s water system must submit an operational evaluation report.

The reason for the regulatory oversight is an overabundance of caution, according to documents from the Environmental Protection Agency and the Florida Department of Health.

“Scientists use worst-case assumptions to work out the lifetime risk of cancer at various concentrations of the chemical. They then set the level where the risk becomes so small it is practically zero,” according to a TTHM fact sheet put out by the Florida Department of Health.

And the small possibility of deleterious health effects is over a lifetime, or many decades, of drinking water with consistent TTHM levels above 80 ppb.

“Drinking water with levels slightly above the drinking water standard for a short time does not significantly increase the risk of illness either,” the Florida Department of Health document states.

The alternative — drinking water that is not disinfected — is much riskier.

One reason for elevated levels of TTHMs — and one cause likely in Orange City’s case — is a situation where chlorinated water sits stagnant for an extended time in areas of a city’s vast system of pipes.

Orange City’s older water infrastructure has been undergoing improvements since 2014. The year before, the city’s water had been found in violation of TTHM standards.

Water can be periodically cut off from the larger system as the city juggles integrating new improvements or replacements with the older system, without resulting in loss of service. In some cases, this can result in “aged” water, which must be flushed from the system.

The longer chlorine is in contact with the water, the more likely the reactions that produce TTHMs will occur.

“Orange City is an older city (established in 1882) and with that age comes a set of challenges including an aging infrastructure,” Water Plant Superintendent Janet Appel said. “Many of the pipes in the city’s water system are very old, and some are obsolete and defective.”

The city completed upgrades to its water treatment system in January, including new chlorine-control systems.

“The city has been working to replace these pipes through a looping project which should be completed by the end of this year,” Appel said. “To reduce TTHMs at the water treatment facilities, a new chlorine control and other water plant upgrades have been installed. Also, a unidirectional flushing program to remove aged water was started. The City is continuing to work hard to reduce the TTHM levels.”

Totals for the city in the final quarter of 2018 did not exceed 80 ppb.

Drinking water quality reports by water provider can be found below.