Water Odor and Taste Issue - October 2018
Overview: The recent issue with odor and taste in the City's drinking water is now resolved. The problem is seasonal, and this season, the "turnover" of water in the city's reservoirs was worse than usual. The extreme change in temperatures — a drop from highs in the 80s to near freezing in just a few days in October — caused the chilled surface water to sink, and the bottom water, which was still warm, to rise. This sudden temperature drop stirred up the reservoirs, bringing water with heavy organic content (see Chart below) to the surface and into the city's water treatment plant.
Background: Naturally, minerals and organic matter exist within the reservoir. As light penetrates the reservoir, organic matter grows and concentrates. The Chl RFU (Relative Fluorescence Units), is a measurement that penetrates the water to determine the concentration of organic matter present. As it dies it settles deeper into the reservoir. The rapid turnover of the reservoir caused a great deal of organic content to suddenly be suspended within the reservoir. This content is not harmful but is a nuisance compound that temporarily impacts the taste and odor of the water. To address this, we increased powder activated carbon doses to absorb the taste and odor causing compounds. After additional monitoring and testing, we were able to find the appropriate levels of powder activated carbon doses and neutralize the compounds.
It is important to note that the organic content temporarily impacts the taste and odor, but does not impact safety levels for drinking water.
The chart below shows the peak levels of Chl RFU in 2015, 2016 and 2017, as well as the readings during the affected time period in October 2018. You can see that our levels in October were much higher than in previous years. Average Chl RFU levels in past years are below 2.0. The peak this year was over 40. This large increase was the reason we had to continually adjust our treatment process over the month of October. To mitigate this occurrence in the future, the City has increased its monitoring frequency and invested in a redundant activated carbon pump.
By flushing the hydrants, the City has cleared the distribution system. If you continue to experience issues with taste and odor, please call the Water Treatment Plant at 419-424-7193. The City will investigate and take appropriate action.
About Algal Blooms & Drinking Water
With regard to drinking water and harmful algal blooms (HABs), the Water Treatment plant has the water tested on a 2 week basis. The water is tested for a combination of items, collectively called cyanotoxins. Each cyanotoxin has a minimum detectable level and measures below that level are considered safe. See the chart below "Drinking Water Health Advisories." Findlay's raw water has never tested at a level that is detectable.
More information about harmful algal blooms and drinking water can be found on this fact sheet and on this EPA page. If more detail is desired, please stop by the Water Treatment Plant at 110 North Blanchard St. or call us at 419-424-7193.