Tempe residents complain of smelly water; officials say algae is to blame

Posted at 5:14 AM, Sep 27, 2017
and last updated 2017-09-27 11:15:11-04

Algae is to blame for "earthy" and "musty" water in Tempe, according to city officials. 

Every year, blue-green algae secretes Methylisoborneol (MIB) and Geosmin into Arizona's water reservoir system, according to Tempe Environmental Services Manager David McNeil. 

"From there, it comes into our watershed and into our treatment plants," said McNeil.

McNeil says the compounds have no health effects and the water is safe to drink. 

Their flavor can be detected at extremely low concentrations which makes it difficult to treat, according to McNeil.

Tempe uses powder-activated carbon (PAC) to absorb these compounds. 

However, residents and businesses are still complaining about the taste and smell. 

One restaurant tells ABC15, their customers are complaining about the taste -- even when it comes to fountain drinks.

So far this year, Shannon Reed with the City of Tempe, says Water Utilities has received 75 inquiries from residents and 10 from restaurants. 

"Almost half of the residential calls, and 60 percent of restaurant calls have come after this last week’s spike, prompting Tempe’s Water Utility Division to take additional operational measures to attempt to reduce concentrations further," said Reed.

These compounds are produced every year, typically between mid-August to the end of September, according to McNeil. However, this appears to be one of the worst.

McNeil says residents can try chilling the water or using a carbon filtration system.

"SRP has advised us we can expect to see this for three to four more weeks," said McNeil.

Recently, Mesa reported a similar issue with their water.

McNeil says ASU's Water Quality team has attributed the high levels to an algae bloom in Saguaro Lake.

For more information about your water, visit or call Tempe 311 at 480-350-4311.