Mankind must harness the power of poo. That's the pungent message from a group of environmental American artists who have channelled their creative energy into toilet composting. They do so in an effort to inspire friends and acquaintances to cherish their bodily waste instead of flushing it away and wasting precious water in the process. The resulting high-grade topsoil is known as "humanure" and the compost heaps inspired by the group are called "humble piles." Cute, no?

Harry Dodge, Sean Dungan and Gail Swanlund are the core members of the 'Testhole' collective and it was Harry and Sean who originally came up with the idea of instigating a project which would test how feasible human waste composting is in an urban environment. They also wanted to see if members of their Los Angeles community could be inspired to stop flushing and join in. Many (quite literally) turned up their noses and abstained, but a die-hard band of enthusiasts identified themselves and before long a small network of humble piles had been set up. Those who participated were given barrels in which to store their humanure. When these were full, the Humble Pile team collected the barrels and emptied the contents into larger containers in secret locations all over the city where the humanure would gradually 'season' over the next 12 months. The reason for the covert nature of the operation is that excessive amounts of human waste would be deemed hazardous by municipal authorities and carted away.

"One of the most obvious issues the project faces," comments Harry Dodge, "is of course the taboo of shit: concerns for cleanliness, safety, feasibility, the 'gross factor,' and the question we received most often, 'does it smell?' We sent invitations to participate to friends and organizations who we thought might be receptive to the idea, and a few were game, but the vast majority of invitees did not respond or were not interested, obviously for various reasons. We were much more successful, especially with sceptical folks, when we were able to convince them [about the idea] in person."

Fighting that poo taboo has been at the forefront of the Humble Pile project. Gail Swanlund adds that the group feels toilet paper companies and other industries "exploit" our natural aversion to bodily waste. Ultimately, though, the Humble Pile scheme sells itself on the many benefits of humanure - unburdening the national sewage treatment system and water supplies, encouraging organic ecological diversity in your garden and forging links with like-minded composters in your community. Gail also believes that municipalities will eventually turn to composting over sewage disposal as a more cost-effective and eco-friendly way of dealing with their residents' excrement. "It's just a matter of time until human waste becomes more effectively dealt with," she says.

In the early stages of the L.A. project, Nance Klehm, a like-minded artist from Chicago, met with Harry, Sean and Gail and decided to take the concept back to her own city where a similar collection of hidden humble piles is now quietly composting away. Klehm describes herself as "a radical ecologist, designer, urban forager, grower and teacher" who grows and forages most of her food in the concrete jungle that comprises her home city. Her experiences foreground the necessary secrecy of the project in an even more densely urbanised part of America. "For Chicagoans," she says, "the biggest challenge is finding a place to store the full bins. Many of the pilers lived in apartments and didn't have outdoor space to leave barrels so during the collection phase it was important that I picked up their barrels regularly so they wouldn't be discovered.

"I also had to find a place to store the 1,500 gallons and then build a collective pile. Projects like this have to be under the radar."

The Humble Pilers' enthusiasm is shared and inspired by Joseph Jenkins, author of The Humanure Handbook - a comprehensive guide to top-soiling turds which is available online. Sean Dungan comments that Jenkins' experiments have been particularly helpful:

The L.A. collective collect another barrel of crap.

"Jenkins' humanure pile model (straw/sawdust/shit/urine/yard waste/kitchen scraps) works wonderfully, and we've used it with success in our own yards. In future iterations of Humble Pile, we'll encourage people to build their own piles, and we'll not supply barrels."

Innovation and experimentation have been the keys to the L.A. team's success. "We're also experimenting with different methods of introducing oxygen," Sean explains, "testing compost catalysts, and we might move one barrel's contents to a more pile-like situation to see how that compares."

For their next trick, the Testhole group are planning a flyer campaign to raise awareness about the Humble Pile initiative. They want to emphasise that after their first year carrying out the project, the rewards are already plain to see. They've inspired people, re-connected with local acquaintances in a new way and, Gail adds, "the water bill was considerably reduced and we grew some outstanding tomatoes this year."

You might remember an earlier article I wrote on guerrilla gardening. Greywater guerrillas are another breed of underground environmentalists who refer to themselves as 'plumbing hackers.' Their aims are; to disconnect many appliances in their homes from traditional sewage systems and recycle water waste in their own gardens instead. Compost toilets and humble piles have struck a special chord with greywater guerrillas, including the chirpy one in the video below who's posted a tour of her comprehensively 'hacked' bathroom on YouTube.

The allure of humanure has captured the imaginations of a sizable number of Americans and humble pilers are also enjoying the kudos that comes with the underground secrecy of their scheme. There are, of course, reasons why ruddy great piles of shit are classed as hazardous material, so we don't recommend diving into the world of composting crap unless you know what you're doing. Only the most dedicated organophiles are likely to get involved at this stage, we'd imagine. But if projects like these provoke authorities into re-thinking the goals of national sewage systems, then they could turn out to be very worthwhile indeed.