Is Gray Water Safe?

In a previous post we told you about the dangers of wastewater, of all of the bacteria or algal blooms that can cause you to get seriously sick. However, not all wastewater is equal. Black water is the water that we’ve discussed before, which contains fecal matter, urine, and other wastes that we know to be toxic. However, we wash dishes and clothes. We brush our teeth, wash our hands, and other forms of cleansing that don’t necessarily create contamination.

This is what’s known as gray water. Gray water is termed such because pure water (white water) is clean and safe, black water (sewage) is dirty and unsafe and gray water is right there inbetween.

There’s a big movement currently towards renewable resources and reuse of materials to get the most out of them. It saves money, time, and the environment—all of which makes it better. But there are some concerns about whether or not the water is safe. Gray water is still dirty—and unsafe for human consumption. But, for gardens and other uses that don’t involve drinking, it might just be a good idea.

Recyclable Uses

So long as no chemical cleaners are used in the making of gray water, then it’s safe for most uses. The main culprits of gray water contamination that makes it unfit for use are:

  • Bleach
  • Dye
  • Bath Salts
  • Cleanser
  • Shampoos
  • Boron Products

Instead of these, you should use biodegradable, natural soaps and cleansers to maximize the efficiency. It keeps the water cleaner and more reusable, and helps to keep everything clean.


However, there are things you should know regarding its safety regardless of whether you store for reuse or just end up with a bunch of water all over the floor. Gray water might not have fecal matter (and therefore the algal blooms), but there are still issues with the water. If you’re not treating the gray water or there’s any form of cross contamination (such as washing dirty cloth diapers), then gray water damage is just as dangerous as black water damage. All of the same bacteria and illnesses can be transferred through it.

And, just like every other kind of water, the damage that it can cause to your home and property are the same. Gray water is touted to have great benefits to irrigation and watering gardens. However, if it can help your roses grow, it can also help mold to grow if it lays around. And, just like rain or flooding, if there’s enough of it around it’ll cause serious damage to the walls, the carpets, and help rot out any wood structure you happen to have in your home. Clean it up—or get help to clean it up, if you need it.

Health Effects

Again, we’ll reiterate: gray water is not safe for consumption, and should be treated like black water. The bacteria contained within are the same as black water, which means the same health effects can come and harm you. These include (but certainly are not limited to):

  • Diarrhea
  • Fever
  • Pneumonia
  • Gastritis
  • Skin and Tissue Infection
  • Headache
  • Chills
  • Muscle Aches
  • Vomiting

This is just a short list of the things that can be contained within sewage-contaminated gray water.

If you’re going to reuse gray water, there are tons of resources all over the place on how to make sure it stays safe and sanitary enough for you to benefit from its reuse. However, if you’re not, be sure to treat it just like black water and keep everything sanitary. The last thing you want to do is harm yourself because you ingested bacteria or viruses from gray water. And if it spills, you need to clean it up quickly. Otherwise, you’re going to end up with more problems than just bacteria.