Investigation - NOLA Drinking Water Inspectors Not Following Testing Protocol

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The Illuminator and Fox 8 requested the Sewerage and Water Board’s current chlorine and coliform sample collection and analysis procedures and compared them with what’s required in government regulations as well as Hach’s instructions. The procedure must be performed immediately after the sample is collected because chlorine dissipates quickly when exposed to sunlight and agitation.

The S&WB’s procedure for measuring chlorine omits a key step. Instead of having the sampler wait for three minutes after the reactant is mixed into the water sample before measuring the amount of chlorine — as detailed in Hach’s instructions with a picture of a stopwatch displaying “3:00” in bold print beneath it — the Sewerage and Water Board calls for the measurement to be taken immediately after the DPD is mixed into the sample.

From Hach literature and conversations with company representatives, taking such an immediate measurement without allowing the DPD to react will result in an inaccurate low chlorine reading, which could mean the test misses chlorine levels exceeding safe levels. Excess chlorine in drinking water can produce byproducts hazardous to human health, including carcinogens. Such byproducts have been detected in Plaquemines Parish’s drinking water recently, a complication from the saltwater intrusion along the lower Mississippi River.

The S&WB procedure is actually doubly flawed when it comes to the DPD reaction. It also leaves out the upper time limit of six minutes found in Hach’s directions, meaning the chlorine reading could be mistakenly high if the DPD in the sample is allowed to react for too long. If the chlorine level is, in fact, low, it would mean there was not enough in the water to prevent bacterial growth, a violation of federal and state regulations. The failure to properly measure chlorine in water may be a significant factor in one of the Illuminator’s key findings: Staffers routinely spend far less time at sampling stops than regulations require to obtain reliable data.

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https://lailluminator.com/2023/11/08/new-orleans-water/