We all have the best intentions when it comes to caring for our planet. (Yes, I really do believe that) And we’re all doing our best efforts to navigate those muddy waters between making the absolute greenest choices and still functioning in modern society. So sometimes, we see a “solution” that seems green on the surface but don’t realize that it might not actually be all that helpful - or even actually be worse than the problem it supposedly solves.
I first thought of this issue when I read news stories (and I’m sure you’ve seen them, too) about people who chose to paint their lawns green so as to have the ideal yard without wasteful irrigation. On the surface, it sounds like a great idea. You don’t have to give up your lush yard, but you also don’t spray ever-more-scarce water onto the grass.
Of course, there’s more to the issue than just that. Regular readers of this blog know we talk a lot about virtual water, and how every day products often use massive quantities of water to be processed and shipped. We usually focus on our diet, but today, let’s take a look at the water imprint of the green paint used on our lawns and see if it’s actually better than growing grass.
To research this article, I wanted to review this can of lawn paint from Amazon. Unfortunately, I couldn’t find a list of ingredients anywhere (supposedly this information is a “trade secret”) which just raised all sorts of red flags for me. Sure, you should protect your business investments, but how are users supposed to determine whether your product is actually green? Since we couldn’t look at the actual contents of lawn paint, I had to settle for the ingredients of spray paint, which may not be the same, but are the closest approximation I can find.
Spraypaint is made of three primary ingredients: the pigment, the solvent, and the propellant.
The pigment is the ingredient that gives paint its color. In the case of green paint, the pigment is commonly a chemical called phthalocyanine. This, in turn, is created via a process called chlorination, in which chlorine is added to other chemicals. Chlorine, in turn, is produced by combining sodium hypochlorite and water. I could keep breaking this down, but the long story short version is that even “green” paints (or green paint) have a long chain of processing that almost certainly involves a hefty water footprint.
Let’s move on past the pigment and instead look at paint solvents. Common solvents are turpentine, methylated spirits, acetone, and others. You can lead about the negative impact turpentine production has on water here, and acetone is made through a chemical process involving propylene. Propylene is a byproduct of oil refining, so let’s give it the same virtual water footprint as gasoline – 2:1. “Methylated spirits” are essentially ethanol with additives, and ethanol has a virtual water footprint of 2,854 liters of water per liter of ethanol. Let’s say that the solvent in grass paint has a virtual water footprint of roughly 2,000 liters per liter of paint.
The paint we’re examining covers about 500 square feet of lawn and has about 1.375 gallons of water in it. That breaks down to a little over a 350 square feet per gallon of water, or 92 square feet per liter.
By comparison, a well watered lawn needs .62 gallons (2.3 liters) of water per square foot. If you water twice a week for 15 weeks (which is how long grass paint lasts) you’ll end up using just under 35 liters of water per square foot. So technically, painting your lawn saves a bit of water, but still uses about as much as a hamburger. If you really want to save water in your lawn, just let it go brown, or switch over to drought-tolerant plants.