Some Tempe residents have noticed a change in the smell and taste of their tap water, but the city says there’s no reason to worry. 

Over the last few days, Tempe’s tap water has -- for some residents -- taken on an earthy smell and taste. The cause is a little convoluted.

Runoff from the Sunflower Fire into the SRP watershed system has increased the particulate matter in Tempe’s water supply. To most effectively filter out those particulates, the city has temporarily stopped treating its water with carbon. Amanda Nelson, a spokeswoman for Tempe’s water department, said the carbon usually removes the aroma, which has a tiny bacterial cause.

“Algae, particularly blue-green algae, can produce a couple of chemicals that can give off a musty or earthy taste and odor in the drinking water," Nelson said. "It kind of fluctuates depending on the time of year, and it is purely aesthetic. There are no harmful [or] adverse health effects.”

Nelson says because of rain storms in the forecast, the city plans to suspend treating its water with carbon through the end of the week.