Top navigation


Eco-Machines for Water Treatment

By Jennifer Chesworth

An Eco-Machine is a water treatment system using plants and microbes, traditionally enclosed in a greenhouse or in external constructed wetlands with aquatic cells inside a greenhouse. Based on the design concepts of John Todd, eco-machines are essentially water gardens that create a controlled environment where natural processes work efficiently to purify water without the need for hazardous chemicals.

Located in Central Pennsylvania at the Julian Woods Community, this eco-machine, completed in 1993, treats effluent from twelve households while providing greenhouse space for vegetables, herbs, and a small cut flower business.

The effluent initially enters the system into a simulated “marsh.” It is then pumped into holding tanks.


Four aerobic tanks, each containing a set of plant and microbial life for distinct treatment stages, perform the primary water treatment at Julian Woods.

The water is then pumped through an ultraviolet light unit that destroys any E Coli or other bacterial life that may be present in the water. This unit is not always a part of eco-machines. It was required by the state of Pennsylvania as part of this experimental system.

Because the system was considered experimental at the time of construction, a discharge permit was not an option for Julian Woods. Evapotranspiration was, however, already an approved method. The state required a second, full size greenhouse as part of the system at Julian Woods, to fully perform the necessary evapotranspiration and to prevent stormwater over-flow. This provides residents with the added benefit of plenty of greenhouse space for private and commercial use.

The eco-machine at Julian Woods was funded by a grant from the Pennsylvania Department of Energy.

For more information on Eco-Machines, please see