A surprise greeted Oberlin residents when they opened their March water bills — attached was a notice that TTHM levels have peaked above drinking water standards.
“Our water system recently exceeded the maximum contaminant level (MCL) for TTHM,” the notice said. “The average level of TTHM over the last four quarters was 0.081 mg/L. The standard for TTHM is 0.080 mg/L.”
So what exactly does that mean to water department customers? Not a whole lot, according to the water system’s superintendent, Jerry Hade.
“There’s really no reason for anybody to be upset about it or for it to cause any alarm,” Hade said.
Understanding exactly what TTHM, or total trihalomethanes, are takes a little explaining.
“All surface water systems have naturally occurring organics dissolved in the water,” Hade said. “When we process that water, we are required to disinfect it, to make it safe for people to drink. We are required to use chlorine. All surface water systems in the country have to use chlorine and we have to have a residual amount in all points of the distribution system.”
When the chlorine combines with organics found naturally in the water supply, they form trihalomethanes.
While there are several types of trihalomethanes, there are four types the Environmental Protection Agency monitors. Add them up and you get total trihalomethanes, or TTHM.
The EPA stipulates that water distribution companies can’t exceed 80 TTHM per billion parts in drinking water. If they do, the distributor must issue a notice of violation.
One of Oberlin’s samples tested for 81 TTHM per billion parts.
“In this case, we had an unusually high sample — for what reasons, I’m not sure — and I honestly don’t believe the sample is correct,” Hade said. “But we’re stuck with it because they only allow us seven days to take the sample but they allow the laboratory to take 14 days to test it. In this case, they didn’t test it until the 10th day.”
Even that explanation may be oversimplifying things a bit.
The EPA mandates water distribution plants must take samples of the water from certain locations in the system every quarter of the year. They then average the sample against the previous three samples from that same location to calculate the TTHM level of the water.
The sample in question for Oberlin was at 144 TTHM per billion parts.
“We don’t know what happened to that sample, but it was unusually high,” Hade said. “It was 144. We have no choice but to use this result and average that out for that quarter. It’s really a tight situation, and there’s nothing we can do about it.”
Even though TTHM levels for that location have tested below the limit since the questioned sample was taken, Oberlin water customers may receive a notice of violations in future water bills.
The sample that was taken in the first week of January is below the level now, Hade said. “We still have to use that sample the next quarter, and then the next quarter. We could be below, which we most likely will be, the limit for the next three quarters, but because of that sample, we could end up having to issue a (notice of violation).”
Oberlin takes samples from two locations in its distribution system each quarter. The samples from the other location came back well within the limits.
“The other test was fine, and has been fine,” Hade said. “We’re not really even saying factually that the whole city is affected. We just got this one sample, from one location, from one dead-end line.”
Water in a distribution system that sits for a while in a dead end of a water line can show higher levels of TTHM than water that is steadily flowing through the lines.
Hade also believes there’s some question on the validity of the sample that tested for abnormal TTHM levels due to issues with the laboratories that conducted the test.
“We sent the sample to Summit Laboratories and they had an issue with their equipment,” he said. “They forwarded our sample to another lab called Brookside Laboratories. This sample is so sensitive that if someone is working in an organics lab down the hall and walk into the room without changing their lab coat, it could affect the results of the test. That’s how sensitive it is.”
There is even some question to just how much of a hazard high levels of TTHM pose, according to Hade.
“If you do the research, you’d have to drink two liters a day of water with elevated levels of THMs for 70 and a half years, and then you may — it doesn’t say you will, but you may — get bladder cancer,” he said. “That’s what the literature says. We are one part per billion over under these new rules at one location in the city of Oberlin, which is a dead-end line.”
According to documentation from the federal EPA, customers do not need to find alternative drinking water sources, such as bottled water, nor do they need to boil their water before consuming it.
Scott Mahoney can be reached at 440-775-1611 or @sm_mahoney on Twitter.
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