Why sand has more bacteria than water at the beach
On any given day, Hawaii’s beaches are enjoyed by many. But a UH Manoa researcher cautions sun worshippers that there may be high levels of bacteria in the sand.

Manoa researcher Tao Yan led a team testing Hawaii’s water and sand beaches and found a higher amount of bacteria in the sand than in the water.
To find out why, the team created laboratory simulations of beaches and seawater contaminated with sewage to observe how overall bacterial populations — including fecal bacteria that cause illness — change over time.
In the lab simulations, Yan’s team found that bacteria tended to decay much slower in the beach sand than in the water. This could explain why more fecal bacteria is typically found on the beaches than in the nearby water, the researchers said.
The study was published in the journal Environmental Science & Technology.
