Graywater 101: What It Is and How To Use It

The water that comes from your showers, bathtubs, sinks and washing machines doesn’t have to go to waste. Your landscape could benefit from it!

We occasionally get phone calls from customers asking questions about graywater, from what it is to whether it’s safe to use and if any permits are required to do so. Rules vary from city to city, so here’s the lowdown in San Antonio.

Graywater is the water that comes from showers, bathtubs, non-food preparation sinks and washing machines. In other words, it’s water that doesn’t have food or bodily waste in it. In contrast, water from toilets is sometimes referred to as “black water.”

Why does this matter? Graywater is in a ‘gray’ area, so to speak. It’s not exactly filthy dirty, but you probably wouldn’t want to drink it either. This water is prime for watering ornamental plants and even some (very select) vegetables.

It is legal in San Antonio to use your graywater and you don’t need a permit or special permission. However, City regulations limit the reuse of graywater to single family homes. Water must be used to water your property only and areas with vegetation. All discharge lines must also be at least 10 feet from the edge of your property.


There are many ways to rig hosing from a sink, bathing area or washer. But the most popular method I’ve seen is to run a hose from a clothes washing machine in the garage out a back door to the yard. In fact, two of my friends were having issues with their washer drainage pipe and decided to utilize the graywater to irrigate their plants. Problem solved.

It’s up to you how you do it, but be extremely mindful of what you put down the selected drain — remember that it is going out into the environment. Laundry detergents also can contain phosphates that wreak havoc on the environment. Look for cleaning solutions marked ‘phosphate-free’ or ‘biodegradable’ when selecting products to use with a fixture that leads to your backyard.

Is graywater right for you? If you’re using graywater from a regular source (i.e. a clothes washing machine), you’ll have a decent amount of water to put down often. Keep that in mind if your landscape consists of mostly native and drought-tolerant plants. Since their watering requirements are minimal, they would likely be unhappy with the amount of water offered by a regular dousing from household fixtures.

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