Can Graywater Re-Wet the West?

Plants love bathwater. Photo: half alive - soo zzzz / flickr (licensed under CC BY-ND 2.0)

It’s perplexing that we still water our landscaping with drinking water. The West is in a historic thousand-year drought, it never seems to rain anymore, cities around here support participation in water-wise gardening and sprinkler-doctor programs, and yet.

Every drop of water that comes out of your hose and straight into the ground has been deemed of high enough quality to put into your body. Landscaping plants have lower standards. In fact, many garden hoses degrade water enough that you’re not supposed to drink what comes out the end, but plants don’t care.

“Kiddo bathwater might be the biggest untapped resource in the West.”

The average American family of four uses 400 gallons of water per day. One-third of that goes to outdoor uses, half of which is wasted on evaporation, runoff, or over water. It doesn’t really take a genius to realize we can’t keep this up.

But look at it this way: Every gallon of slightly dirty water you send down the drain is a wasted chance to save a gallon of fresh, drinking-quality water you’ll apply to your garden from the tap (and pay for). But it does matter how dirty the water is and not all used water is fit for the yard.

What is graywater?

Graywater is water that been used once already, and there are varying different “quality” designations.

• Light graywater is barely used at all. Think of running the tap to heat up the shower. This water is as clean as the bucket you catch it in.

• Graywater has been used once as bath, shower, or washing machine. Definitionally, this contains only soap residue, and perhaps trace amounts of oil and hair. This is as “used” as we want.

• Dark graywater comes from kitchen sinks, where the content of grease and food particles is higher. This water is too dirty to use outside.

• Black water is toilet water (or washing machine water if you’re running cloth diapers). Keep that flowing straight to the municipal water treatment facility.

How do I use graywater?

Since 2005, Colorado has been working out how to regulate graywater use. After a lot of delays, the effort is expected to be picked up again this year. But the gist is that the Regulation 86 defines different classes of graywater (as above) and gives municipalities control of how and whether to allow graywater systems within their jurisdictions.

System is the key word here. Since municipalities don’t want human-tainted water flowing unmitigated into aquifers or streams, there are regulations in the design of systems that ensures the water stays subsurface. That means a tangled path through bureaucracy and permitting to get a system in installed. Luckily, there is a much simpler and less expensive way.

The humble bucket

Bucket irrigation isn’t for everyone. It can be heavy and time-intensive, but if you’ve got some arm strength, a little time, and a relatively short walk from tub to outside, it’s a no-brainer. Simply get yourself a container you can carry and start catching good water (think: shower heat-up water, drip water from your dish drying rack, and for families, bathwater).

Kiddo bathwater might be the biggest untapped resource in the West. Kids bathe a lot and in standing water. This water is easy to collect and the kids might think its fun.

The system we’re using at our home in Lafayette requires a few five-gallon buckets and a hose (although it’s worth noting that the idea originated with my kids and an empty 2-liter soap bottle). We siphon from the bath, out the bathroom window and to the ground below, where we catch it in a five-gallon bucket. We then transport that water immediately (don’t store graywater) to a few other buckets into which I’ve drilled a few small holes. I move those around the yard depending on which plant is thirsty.

In time, we might add a few drip-irrigation barbs to the bucket so we can water multiple plants and more slowly, but for early prototyping this is pretty good.

What should I water with graywater?

• Outdoor plants only. Keep giving freshies to your indoor plants.

• Only water at the ground. Ensure graywater doesn’t get on leaves or edible parts of the plant.

The new wet West?

We xeriscaped our garden beds a few years ago and replaced our turf with water-sipping native grasses, so we might end up with a new problem. We’ll likely have more bathwater than our plants can drink. In any scenario, we’ll have the lushest garden in years. That’s not exactly a picture of the drought-stricken West right now, but with just a little bit of effort, it could be.