A level of haloacetic acid above the maximum allowed was detected in Mannington's water system during the 2nd and 3rd quarters in 2012.
Recently, a letter was hand-delivered to residents, letting them know a drinking water standard was violated.
The legal level of haloacetic acid is 60 UG/L, and Mannington's average for the second and third quarters of 2012 was 63.3 UG/L.
Resident John Haught said he's concerned for his family's safety.
"I'm concerned for the city of Mannington. Its overwhelming that we're drinking this water that could cause damage to people," said Haught.
Haught, along with many other citizens, wondered why it took a year for the city to tell them about the problem.
"We have a nine-month-old granddaughter at home, and she's drinking this water, and we just find out about it? It's been a year. My daughter was pregnant and we didn't know anything about it. What do we do about this, what's the city going to do about this?" asked Haught.
Mannington City Council addressed the problem at its meeting on Monday. Mayor Robert Garcia said the city sends out notices when it gets the results back from the state, and that this particular contamination isn't a threat to the citizens.
"If you drank a liter of this every day for 70 years, and it would have to be low like it is now, then it would affect you. Now, it won't affect you at all," said Garcia.
Garcia said if the city found out it was something dangerous it would notify residents right away and protect them. Starting on Tuesday, 200,000 gallons of water will be flushed from the system.
"We're going to be flushing the hydrant the 7th through the 9th. So we'll have all the hydrants flushed out and it will bring everything back down to normal," Garcia said.
Mayor Garcia said the only thing the citizens need to be concerned with during the flushing is to not do laundry, it might stain the clothes, but everything else like showering and the drinking water will be fine.