A few months back, my partner and I went on a trip through the American Southeast.

Since she’s a nursing student, and I am some kind of writer, our trip’s logistics were bound by frugality.

This meant camping, sleeping in our rental, crashing at shady motels, and occasionally dipping into cheaper options on Airbnb.

One night, after an eight-hour drive through most of Georgia, we negotiated a one-bedroom situation. The price was right, the host seemed nice, and everything went pretty much as planned.

The next morning, I received this “private” review in my inbox:

“I’m not sure if it’s a water conservation thing, but you should probably flush the toilet in other people’s houses.”

A few things: First, the message makes me inexplicably angry. I retrieve it every now and then when I’m feeling mellow and need an amping, just to view that particularly annoying passive-aggression. Secondly, the non-flushing was partially the result of miscommunication, as I thought our host had a toilet in her own bedroom, thusly allowing us to do what we pleased with the hallway one.

But, most importantly, yes, it is a water conservation thing. Because if you’re still flushing down number ones, you’re almost as bad as a climate change denier.

“THE TOILET IS THE biggest waste of water in your house,” says Kenneth Messer. “There’s nothing else in your house that will dump nearly two gallons of water in as short a period of time.”

To be fair, Messer has a dog in this fight. He’s the owner of Why Flush, a “toilet water neutralizer” liquid that can be dropped into your toilet to counter the “gross” aesthetics of letting urine stick around in the bowl. According to the website, each 16-ounce bottle of Why Flush saves approximately 1,200 gallons of clean water. “It puts the ammonia smell to sleep. It keeps the water from being yellow. It keeps it from staining the toilets,” Messer says. “It makes the whole idea of letting it mellow a more user-friendly experience.”

Messer has been pushing the product since 2012, and sales have grown, in part because of word of mouth, and in part because the current drought in the American Southwest is breaking records every day. But there’s still plenty of folks who refuse to keep their pee adrift. “These are people at water conferences that know very well what is happening,” he says. “And they’re like, ‘That is so gross, I’ll never do that.’”

“When we’re working with utilities to sell ideas on how to conserve, many don’t want to message that,” says Ora Chaiken, of Water Smart Software, a San Francisco-based start-up that focuses on how to get consumers to conserve water. “They think it’s too scatological.”

There are other “taboo” ways that aren’t “on message” either: Urinating in the shower, turning off the water to your toilet and flushing it with used water instead, not washing your jeans or underwear just because you wore them for a few hours. And, there’s this: “Shower with a friend,” Chaiken says. “It may not save a ton of water, but it is a lot of fun.”

What happens in the shower stays in the shower. Mark Sayer / Shutterstock WHILE CHAIKEN IS QUICK to point out that the act of not flushing down number ones is not going to solve the drought—lawns are, by far, the worst waste, with 50 percent to 60 percent of residential water going toward irrigation; toilet leaks are also a worry and should be checked by putting a drop of food dye into your tank and checking the bowl in 15 minutes—it is an easy way to save a few gallons a day. But unlike other one-time adjustments like installing high-efficiency shower heads or replacing lawns with native plants, keeping yourself from flushing is a long-term behavioral change. So, how do you un-teach someone to press the flusher?

To Messer, the answer is inevitable and will occur when the cost of water reflects its true availability. “If oil was at the same level as water was right now, gas would be way higher,” he said. “At some point, common sense is going to kick in.” But beyond the financial motivator, there’s another powerful incentive to be considered: shaming.

In his book Fostering Sustainable Behavior, psychologist Doug McKenzie-Mohr describes a study about trying to get college students to conserve water while using a gym shower. If a sign was posted in the shower urging students to turn it off when they weren’t using it, only six percent followed the instruction. But when a researcher was planted in the shower and silently performed the conservative act, a whopping 49 percent of students followed along. If two researchers were planted, that number rose to 67 percent of students.

The problem with toilet usage, of course, is that it’s inherently a private act. You usually can’t be a visual example of not flushing down urine without putting your legal freedom at risk. Even the offices at Water Smart don’t let it mellow, not least because they share their bathroom with another company. “Everyone flushes every time,” Chaiken says. “But it’s really different if you’re doing it inside your home, rather than in an office environment.”

There’s validity to that concept. Most activities are taboo for a reason. “Definitely in countries where they don’t have great sanitation, there’s more disease that spreads because waste isn’t disposed of properly,” Chaiken says. (And, yes, Ebola can be transmitted through urine.) So, OK, maybe an office mellowing rule isn’t going to fly. But how do you get people to do it in the privacy of their own homes?

INACTION IS A LEARNED behavior. Messer was brought up never flushing, and that’s stuck, even if it wasn’t always pleasant. “We were surfers, so we were in tune with the environment,” he says. “But it got bad sometimes, man. When you don’t have air conditioning and you’re living in a house with three dudes, it can get overwhelming.” For me, however, it was a behavior I learned later in life.

I grew up in Chicago, and flushing is just an automatic thing there. It’s not that our family wasn’t environmentally conscious—we separated our recycling and followed restrictions when watering our lawn. But flushing was the standard action, no matter the waste being disposed of. It wasn’t until my aforementioned partner—who grew up in California and through previous droughts—mocked me relentlessly that I changed my habit.

And maybe that’s the answer. The tangible benefit of “letting it mellow” is that it saves gallons of drinkable water a day, so proponents of the act have highlighted this fact. But that’s trying to appeal to a person’s sensible side, and that rarely works. Maybe the message needs shifting to the intangible benefit of doing so: the righteous judgement that you can enjoy when you come across someone who doesn’t let it mellow. While conserving water is a rewarding act, it’s nothing quite like having the ability to respond to someone’s complaint about your not flushing with: “Oh, you still do that?”