Miki Agrawal. Sarah Jacobs First, Miki Agrawal encouraged women to toss their tampons.

Agrawal is the brains behind Thinx, the "period-proof underwear" startup that makes garments out of a special fabric designed to prevent menstrual blood from leaking and staining.

Now, the serial entrepreneur is taking on toilet paper.

Her new venture, Tushy, sells a portable bidet that attaches to a regular toilet and transforms it into, as Agrawal says, a "booty washer." Agrawal and cofounder Monica Pereira are on a mission to change the way Americans clean their behinds, in an effort to save the water and trees that go into making toilet paper.

In March, the company announced it raised a seed fund of $500,000 from angel investors, including Luke Sherwin and Neil Parikh, the cofounders of mattress startup Casper.

"The way you wipe yourself hasn't changed since the late 1800s," when modern toilet paper was invented, Agrawal tells Business Insider. "No one wants to talk about it, so no one is innovating. It's causing major issues for the planet."

On average, Americans burn through 57 squares of toilet paper a day and 50 pounds a year. Making a single roll of toilet paper requires 37 gallons of water and some 1.5 pounds of wood, according to Scientific American.

There may be an easy solution to saving some 15 million trees annually, according to Tushy: Americans need only swap toilet paper for bidets.

The bidet made by Tushy is actually a device that users insert under their toilet seat and connect to the toilet's clean water supply. When in use, a nozzle lowers and ejects water. Users can adjust the water pressure, temperature, and jet stream angle for maximum comfort.

The company claims that using its bidet for a week requires just 1.3 gallons of water, compared to the 55.5 gallons of water wasted when you use toilet paper for a week.

Agrawal is half-Japanese, half-Indian — joining two cultures that both routinely use bidets. In the US, she knew there was a weirdness factor around the hygiene product. When she set out to design a portable bidet accessory, she wanted it to be "cool," drawing inspiration from Apple product designs. "We wanted to look like an iPhone next to your toilet," Agrawal says.

The bidet comes in two models: a cold-only unit that costs $69 and a dual temperature unit that runs $84. It's available in three metallic colors, à la iPhone.