RWIs are spread by swallowing or having contact with contaminated water. What’s the most common RWI? 

"Unfortunately, it is fecal material in the pool that causes these disease."

Sacramento County Health Officer Glennah Trochet says even very well maintained pools can be dangerous.

Sacramento County has 2,200 public pools and spas. Environmental Health Division manager John Rogers says last year health inspectors shut down 216 of them. 

"Probably the two biggest problems that we see that result in pool closures are the lack of disinfectant in the pool and also the fencing around the pool there’s usually a problem with a gap."

A gap in the fence means unsupervised children could wander near the pool. Health officials say the vast majority of local public pools are in good shape and with the proper maintenance and good public hygiene, they can be a safe and enjoyable experience.