The waste water from your shower, washing machine and bathrooms sinks is known as “gray water,” and in January the rules on how to reuse this water changed.

KJZZ listener Rebecca Smith-Kevern wondered why there are laws against drinking this water, and asked via Q&AZ.

The main reason why this waste water is regulated is because it can make you sick.

“If you wash your hands you’ve made a deliberate effort to put that stuff off of your hands that you don’t want coming into your body,” said Dave Dunaway, who oversees water reuse for the Arizona Department of Environmental Quality.

Gray water reuse can be an eco-friendly option for landscape irrigation, home gardening and composting, and you don’t need a permit to reuse the water on residential properties.

However there are rules to lower the chance that bacteria in the water could enter a drinking water source.

“In a nutshell you want to keep the gray water on your property, you want to avoid human contact, standing water or cross connections with your drinking water system,” Dunaway said. “You want to keep hazardous or infectious materials out of the gray water.”

Gray water shouldn’t be used if a groundwater source is less than 5 feet underground and shouldn’t be sprayed. Instead, use it in drip or flood irrigation as long as it doesn’t run on someone else’s property.

Dunaway stresses that gray water is different than “black water,” which is waste water from the kitchen sinks and toilets. All black water should be sent to a water treatment facility and not reused.