SENECA — Seneca Light and Water is in the middle of mandatory testing to prevent water contamination, Utilities Director Robert Faires said Thursday.

“DHEC (Department of Health and Environmental Control) requires every entity with a water system to have a backflow prevention program,” Faires said.

Backflow is the flow of water and other substances, such as fertilizers and contaminants, back into the drinking water supply from any source other than the water distribution pipes. There have been several documented cases of pesticides and even parasitic worms entering drinking water lines in instances when backflow was not properly controlled. Any house in Seneca’s service area that has a sprinkler or irrigation system must be tested for backflow.

The Daily Journal/Messenger had received complaints of letters from Seneca Light and Water informing some residents of an approaching deadline by which they must have the water lines at their residences tested for backflow. A list of independent testers is provided in the letter, and the customers must pay for the services.

Robert Bird, supervisor of auxiliaries for Seneca Light and Water, said on average a backflow test costs a customer from $40-$80, depending on the size of the residence and the tester’s individual price.

“We just send a reminder letter, that’s all it is,” Bird said. “We send it 40 days before a test is due. After the due date, we send out a second letter showing the test is due. We then send a third notice informing the customer they are in danger of losing their service. After that, they are shut off.”

Bird said they make about two shutoffs a year due to noncompliance with the mandatory testing. Faires said his customers are informed of this requirement when they first receive the department’s service. Both Faires and Bird admitted human error often contributes to mistakes in the process. Letters informing supposed residents of an address are often forwarded to owners even after they’ve moved and with no response. That leaves Seneca quite often without any knowledge there is no one living at the address in question. It isn’t uncommon, Bird said, for a test due date to expire at a house in which service has already been cut off in the first place because no one lives there.

“Ninety percent of the time folks will call us to tell us they no longer live there,” Bird said.

Bird developed the testing system used by Seneca Light and Water because, while DHEC mandates backflow testing, it does not provide any uniform standard for the testing procedures, Faires said.

“This testing has received full approval from DHEC,” Faires said.