West Columbia, SC (WLTX)- A judge has set bond at $525,000 for a man authorities say tried to poison dialysis patients.

Authorites arrested 49 year-old Donald Foster of Batesburg-Leesville on Wednesday and charged him with attempted murder and second-degree burglary.

"I've been coming here for 5 years," said Darlene Williams who receives dialysis 3 times a week from Fresenius Medical Services.

"This is like my second home, my second family."

That's why Williams was surprised to find out a former employee tried to poison them by putting bleach into a water holding tank in order to contaminate the water supply for dialysis patients.

"I am a little puzzled, he seemed like a nice guy. You really don't know anybody," said a frightened Williams.

The Lexington County Sheriff's Department says Foster became a person of interest early on. He was suspended from his job as an equipment manager at Fresenius Medical Services on July 2nd, and then broke in July 6th.

The medical services center released this statement to News19:

"Our facilities have safety protocols in place designed to detect the presence of impurities in our water.  These checks occur prior to the first session of dialysis therapy each morning and multiple times throughout the day while the clinic is open. During a routine early morning check, our staff was able detect a contaminant and take appropriate steps to correct what occurred.  Although patients' treatments were slightly delayed, no one was harmed and all of our patients received their scheduled treatments that day.   We are proud of our staff and are grateful that they caught this situation."