‘Go with the Flow’ Mobi-Toilet

for the American River Parkway in Sacramento, CA.
We designed this project for the Little Big Loo Competition. This design is meant to inspire conversation and creativity about the sanitation issues faced by our riverside unhoused communities.

The “Go with the Flow” Mobi-Toilet provides a low-maintenance and dignifying sanitation facility for transient camps of unhoused residents in remote, unserviced areas of the American River Parkway in Sacramento, California.

The mobile toilet eliminates the problem of waste-disposal by adapting vermifiltration to a mobile format to produce a superior sanitary, environmental, and deployable off-grid public toilet experience.

It’s user-centric features, regional aesthetic, and ability to reach isolated locations allows for a valuable human-centric solution that respects the dignity of those living in camps, as well as 1.5 million annual visitors who use the American River system recreationally.

The design purposefully limits contact points, with the structure itself, and with users. Linear traffic flow, hands-free door handles, sanitizing mist, and a touchless hand washing station eliminate the need for constant cleaning and maintenance by the city. By utilizing natural ventilation, high ceilings, and eliminating external corridors, the design of the toilet minimizes the risk of transmitting air.

Because these are mobile they can adapt to the needs of unhoused communities in the region, and also can be deployed for other related toilet needs, such as outdoor community events or local parks.

Entrance - Phone Charging, Notice Board & Bench

We selected regional rural materials and deployed them in a contemporary form. In conjunction with the iconic Valley Oak leaf canopy image, these materials communicate belonging, freshness, and activity to our community.

Exit - Hand Washing Station

We utilized color to delineate program activities in yellow as well as to annotate tectonic components of the design, such as green for structure and white for the walls.

Mobi-Toilet Floor Plan

Linear traffic flow, hands-free door handles, sanitizing mist, and a touchless hand washing station eliminate the need for constant cleaning and maintenance by the city. 

Mapping E Coli Contamination

Circles represent e oli contamination counts in the water. The larger the circle, the higher the count. The blue arrow represents the site studied here. 

3 Out of 100 swimmers suffer aliments such as diarrhea from contact with feces-fouled water.

To learn more about this issue, we encourage you to read this article by the Sacramento Bee as a starting point.
E Coli Contamination Map: Nathaniel Levine and Michael Finch II. Source: California State Water Resources Control Board.


In remote parts of the American River parkway, 200 – 300 unhoused people cluster in small communities to avoid police harassment. For years, rotating clusters of 20-30 people have camped along the fence and levy. Without toilet facilities, fecal mater has contaminated the water at dangerously high levels. Here is a typical cluster where the Mobi-Toilet could be deployed:

Understanding the Problem

The Sacramento Bee Newspaper conducted a series of interviews with people who live on site and found that current makeshift solutions include: defecating in the woods, makeshift latrines at the water’s edge, defecating in plastic bags and disposing of it in a trashcan or river, and “Go into the river and poop”.

Constraints that prevent people from making more sanitary choices include: park public restrooms are only open during daylight hours and are not located near camps, walking out of the park to find a business or shelter with a toilet is too far, city portipotty trials have failed, and renting the city’s bathroom trailer for $450 / day is too expensive

The Solution

As a portable structure, the Mobi-Toilet addresses the immediate need while circumventing the gridlocked debate about where the unhoused are allowed to reside.

How the Mobi-Toilet Works

Exploded Diagram of Components Above and Below Deck

These toilets digest waste with vermifiltration, also known as worm composting. We were initially drawn to this idea because there is no sludge pumping required and pump trucks are too big to access remote sites. We soon discovered that the benefits were far greater than reducing sludge- the worms digest 90% of fecal solids in less than one day and the only byproducts are clean dirt and water. This means no odor or pests, no biohazard, and minimal maintenance. There are many different designs for worm composting systems, some even sponsored by Bill Gate’s toilet project. We were delighted to find that TBF Environmental Solutions Pvt. Ltd. in India has created a Tiger Biodigester single toilet that appears adaptable to a trailer design as well as a compatable system that cleans and treats the water for reuse. Here is TBF’s diagram about how it works:

No risk of odor or pests

Slow rate of accumulation

Worms reduce fecal solids by 90% a day.

Safer & easier maintenance

Eliminates waste handling and fecal recirculation.

With clean water as a byproduct, we were able to shift away from toilet paper to toilet seat bidets and reduce water resupply trips for the handwashing station. Bidets are a game-changer- toilet paper costs add up quickly, create more waste to compost, and dirty stalls with loose sheets. They also have some awesome features such as self-closing lids + seats, heated seats, self-sanitization, and night lights.

The electricity needs to run this system are provided by a series of rooftop solar panels that feed a battery bank in the tongue of the trailer (under the bench and next to the phone charging lock boxes.)

While bidets and recycled water are not culturally popular in California, experience has shown us that the right environment and education can make them an elevated toilet experience. 

In terms of introducing the toilet to the unhoused community, we found these guidelines for community engagement with vermifiltration toilets to be a great starting point.

This is a bidet toilet seat. It replaces the existing seat on a normal toilet. Image from Eco Bidet.


Genevieve has a great respect for culture, memory, and the role of art and architecture in preserving both... as well as a strong grasp of the historical and ethical dimensions of architecture. Genevieve is an original, she will undoubtedly have a profound impact on the cultural and international debates in art and architecture.

David Gersten
Director, Arts, Letters and Numbers

She was a fearless, inventive, and determined member of a very strong international cohort of designers. Among her remarkable traits is an infectious enthusiasm and true delight in the often conflicting and onerous process of design, whether it be traditional architectural work, urban design projects, or her more visceral experiential works.

Jim Barnes
AIA Architect

Genevieve immersed herself fully into these projects and was able to analyze them and create unique solutions for them. She’s a self starter, and finds ways to contribute and add value to projects out of her own initiative. She’s extremely professional.

Nadine Schelbert
Creative Director, WET Design

I will always be grateful to Genevieve Marsh for her work on my memoirs. Her design, cover and layout were perfect for me. She took my pictures of my childhood and placed them in such a way that really catches the eye laying them flat on two pages. Genevieve has inspired me and showed me that anything is possible or rather nothing is impossible.

Charlotte Mankin

She plants seeds for ideas that grow our thinking in fresh directions and opens the mind to possibilities that are both practical and new - and in new directions.  What a way to recharge an organization and build a sense that dreams are doable. Her deliverables were delivered in a timely fashion, were executed with precision and exceeded expectations.

Leslie Warren
Chair, Alliance for Environmental Leadership

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