WEST COLUMBIA — A man suspected of pouring bleach into water used at a West Columbia dialysis clinic where he worked was seeking revenge after the firm had suspended him, the local sheriff said today.

Deputies in Lexington County said Donald Foster III, 49, was arrested today and charged with attempted murder and second-degree burglary. He was scheduled to face a bond hearing Thursday.

Sheriff James Metts told The Associated Press that Foster had been suspended without pay on July 2 after it was discovered that he was luring elderly clients of the firm and providing them with prescription narcotic painkillers. Foster was an equipment technician and also worked in patient care at Fresenius Medical Services, the sheriff said.

Metts said Foster devised a scheme in which he returned to the clinic the night of July 7 despite being told to stay off the property. He said Foster sneaked past a cleaning person and poured the bleach into a holding tank so it would contaminate the water supply for the dialysis machines.

“We believe that this individual, with full knowledge and intent to harm or kill these clients coming in for dialysis, that he knew all along what he was doing and that this would kill the patients who would receive this contaminated water while they underwent dialysis treatment in the clinic,” Metts said.

The sheriff said the potential for disaster was averted when workers found a higher-than-normal level of chlorine when they checked the water the following Monday. He said 20 patients were scheduled for treatment that day.

“Thank goodness, his plan failed due to the fact the technicians, even though they had checked the water on Saturday afternoon after they finished all of their clients for the day and took no clients on Sunday and was going to begin back on Monday, they went through their checks and found the high contamination of the chlorine bleach in the water,” Metts said.

Metts declined to provide specifics, but said investigators were able to discredit Foster’s original statement. He said Foster angrily acknowledged he was upset with the supervisors for suspending him.

It wasn’t immediately known if Foster had an attorney.