City of Tempe: Natural changes in tap water taste & smell come with the season

Flickr Photo by Carol VanHook

We are approaching the time of year when some customers may notice a “musty” taste and odor in the tap water. If you do,  it’s not your imagination – and you can rest assured that your drinking water is safe. 

The musty smell and taste come from compounds produced by certain algae, particularly blue-green algae, which are prevalent in warm regions – like ours – with deep storage reservoirs, or lakes. While these algae byproducts can affect the smell and taste of drinking water (even at very low levels), they have no adverse health effects. This typically occurs in the late summer and fall when algae die off due to cooler temperatures and release more odor-causing compounds. Tempe has ongoing partnerships with Arizona State University and Salt River Project to monitor and treat algal growth in the lakes and canals to minimize these occurrences. 

Tempe uses powder activated carbon (PAC) to absorb these compounds and alleviate the musty taste and smell. On occasion, however, the city needs to suspend PAC use for operational purposes which results in noticeable taste and odor changes.

While you may at times experience an earthy smell and taste, your water continues to be safe to drink. During these occurrences, running water through a refrigerator filter or a carbon filtration pitcher, such as a Britta, can improve taste. Chilling drinking water and adding lemon slices can also suppress musty taste and odor.