Drinking water below standards during summer months

September 28, 2016

MERCEDES — Residents clamored on Facebook after they received a letter from the city of Mercedes saying the drinking water levels over the summer months were below state quality standards.

Some asked for a chlorine generator while others wondered why this happened.

Jose Ramos, of CH2M Hill, the project manager who oversees the water system for the city of Mercedes, said the drinking water is back to normal.

Ramos said during the months of June and July, the chlorine level dropped below the Texas Commission on Environmental Quality standards.

“What happened was our chlorine residual in the distribution system dropped below TCEQ acceptable levels more than 5 percent for two months,” Ramos said. “We had (chlorine) 0.2 milligrams per liter and it’s required to be at 0.5 milligrams per liter.”

Chlorine-based disinfectants are used to destroy germs in drinking water. It provides a “residual” level of protection against water-borne pathogens.

Ramos said the water was not completely without chlorine disinfectant, but the situation required a public notice.

The letter sent out by the city stated the water was inadequately treated and might have contained disease-causing organisms that could cause cramps, diarrhea and headaches.

The letter stated the city failed to maintain an acceptable disinfectant residual throughout the distribution system for two consecutive months.

Ramos said a motor in the well pump malfunctioned at the Illinois Avenue water treatment plant, which could have caused the problem.

Ramos said the motor was down for two weeks.

“Because we had a pump out and we were maintaining just to maintain the water demand for the public, we were not able to do that cycling for a couple of weeks,” Ramos said. “That’s what we think caused that low residual.”

Ramos said the high consumption of water during the summer months also could have caused the problem.

He said during the summer months, the water towers drop their water levels during the afternoon hours and then they are filled back up at night. He said it cycles the water in the water towers to get fresh water.

“We were in compliance until Aug. 10 when we did our monthly report for July,” Ramos said. “I don’t think the water was contaminated, but it is possible.”

Ramos said the chlorine levels are being monitored closely.

He said in the month of August there were zero samples below the acceptable levels of residual in the drinking water.

“The drinking water is safe to drink,” Ramos said. “As far as the production of the water, we are in compliance.”