05/20/2025
Something is making our water in Upper Sandusky smell "earthy" and for some people very unpleasant. This is a community wide challenge and everyone is doing their best to resolve the issue.
Let's do some research - thanks to the internet, we have lots of information, here's some we have gathered together:
Today's science word of the day: Geosmin (/dʒiˈɒzmɪn/ jee-OZ-min) is an compund with a distinct earthy or musty odor, which most people can easily smell.
Going deeper: The geosmin odor detection threshold in humans is very low, ranging from 0.006 to 0.01 micrograms per liter in water. Humans are more sensitive to geosmin than sharks are to blood, with humans being able to detect geosmin at 5 parts per trillion while sharks detect blood at one part per billion. While it can cause concern due to its unpleasant taste and odor, it is not toxic to humans. Some individuals are even more sensitive, detecting geosmin in drinking water at concentrations as low as 5 parts per trillion. Geosmin is difficult to remove from water using standard treatment processes, and advanced treatment methods may be necessary.
Possible cause: Blue-Green Algae (cyanobacteria) for which geosmin is a byproduct. Blue-Green Algae is part of the natural water system. They are tiny living things that naturally grow in lakes, ponds, and slow-moving rivers. They’re not usually harmful, however, under the right conditions (warm water, sunlight, lots of nutrients), blue-green algae can grow too much and form what’s called a “bloom.” Some blooms can produce toxins—but not all do. Water is tested to be safe from such toxins. Geosmin is unpleasant but not dangerous.
The good news: All tests show our drinking water is safe. If you are on a public water system, your drinking water is protected by your local water supplier to address possible contaminants, including blue-green algae and associated toxins. Water suppliers are required to treat, disinfect, and monitor drinking water for their customers. If contaminants are detected in your water supply above levels established to protect human health, you would be notified by your local water supplier and provided instructions.
What might be required to remove it? Our local water system has already increased the amount of filtering and use of activated charcoal in the process. These are the standard first steps. More advanced and expensive methods include:
1. Ozonation. This is when Ozone gas is bubbled through the water. Ozone breaks down geosmin at a chemical level. It's fast and effective but more expensive, so not every facility uses it.
2. Advanced Oxidation Processes (AOPs) Uses a combination of ozone, hydrogen peroxide, and UV light. Very powerful at breaking down geosmin and other tough contaminants.
