For 10 years, some residents in Denmark, South Carolina, have been suspicious of the rust-colored water coming from their taps.
They’ve been collecting samples in jars and using bottled or spring water, even though the local and state government assured them it was safe.
But through a Freedom of Information Act request and a one-year investigation, CNN has found new information that may cast doubts on those assurances.
The state government was adding a substance to one of the city’s four wells, trying to regulate naturally occurring iron bacteria that can leave red stains or rust-like deposits in the water.
The substance, known as HaloSan, was not approved by the US Environmental Protection Agency to disinfect drinking water.
CNN was told by the state that it has been adding HaloSan to the water in Denmark since 2008.
A spokesman for South Carolina’s Department of Health and Environmental Control told CNN in an email that it believed HaloSan was EPA-approved for drinking water based on the way the system was "advertised."
An EPA risk assessment from 2007 shows that HaloSan can be a "significant eye and skin irritant."
The EPA told CNN that HaloSan is not a registered pesticide product and has not been reviewed by EPA’s pesticide program.
But Edwards says he couldn’t let go of a nagging feeling that there was something missing, especially after finding red flags, like a 2010 local newspaper story where a city official declared the water had safe lead levels nine days before the testing was conducted.