Although the chlorine in your pool and the salt system you run are meant to kill germs in the water, sometimes they're not 100 percent successful. As germs evolve over the years, they can become resistant to the effects of chlorine and survive for days before being eradicated, according to the U.S. Centers for Disease Control and Prevention. Because of this, swallowing even the tiniest amount of water can make swimmers sick.

For Phoenix pool owners, this becomes especially important when they have small children swimming in the pool who may not know better and will swallow the water without thinking twice. Additionally, accidents happen and even adults can wind up with some pool water in their stomachs, which can cause recreational water illness.

What is it?
The CDC reported that coming in contact with contaminated water through swallowing, inhaling mists or aerosols in swimming pools and hot tubs. It can also be caused by chemicals in the water that evaporate and create issues with indoor air quality. This can be troublesome if your pool is connected to your house in any way.

Medicine Net reported that there has been a significant increase in the number of RWI outbreaks associated with swimming over the past two decades. Cryptosporidium, which has become the leading cause of pool-related illnesses, can survive for days even in well-managed swimming areas. Between 2004 and 2008, cases of RWI from cryptosporidium increased by more than 200 percent, with 3,411 cases reported in 2004 and 10,500 cases in 2008.

Some of the most common RWI symptoms are diarrhea, skin rash and respiratory illnesses caused by poorly maintained hot tubs.

How do I prevent it?
Because chlorine can sometimes be ineffective in killing germs, RWI can be prevented by other means to supplement the chemical's work. The Arizona Department of Health Services suggested that all swimmers should be instructed to not allow the water into their mouths or swallow it if it does. Also, for younger children, parents should make sure that they have gone to the bathroom enough and not wait until the last minute to ensure that they're in the clear.

Additionally, swimmers should practice good hygiene and shower thoroughly with soap before heading into the pool. This can help prevent any germs from contaminating the water and infecting other swimmers. 

Owners should talk with their Phoenix pool service company about proper maintenance and cleaning strategies that can be instrumental in preventing any instances of RWI.