The woody, musty, earthy taste that shows up from time to time in our drinking water is normally due to natural causes. The main culprit: algae. When blue-green algae end their lifecycle they emit an oily substance called geosmin, which has a distinctive earthy taste that humans can detect in even small concentrations. While this added flavor in drinking water can be annoying, it poses no health hazard.

While water utilities have long worked to reduce the prevalence of the offensive taste and odor, customers can also have some success by filtering their water. Keeping the water cool also decreases the taste’s intensity.

But the most effective way to improve water’s taste and odor is at the source by reducing the food supply to the algae that creates geosmin. The algae feed on nutrients that wash in from the surrounding watershed. One source of those nutrients is fertilizer that washes into lakes from the lawns of lakeside property owners and others in the watershed. Limiting such fertilizer will reduce the amount of excess that washes into our streams and lakes during heavy rains.