N E X T .

From Bowel to Tidal Movements「便便」船

2019-2020 Envisioning eco-toilets for unsewered stilt houses (棚屋) in Tai O fishing village.

  • Manifestation probes (‘provotypes’) ‧ floating sanitation garden ‧ earthworms ‧ informal housing ‧ coastal nutrients pollution

Supported by PolyU School of Design Startup Fund (Hong Kong) in collaboration with Adriana Calbiati, Guilherme Castagna, Sarah Daher (permaculture design), Olivier Habimana (water microbiology), Daniel Elkin (spatial agency design), Michelle Law (earthworm ecologies), Bill Lehman (Ecologists Without Borders), Chi-Yuen Leung, Xialu Norah Wang (social science), Hermann Paulenz (environmental engineering), Bayden Russel (marine ecologies), Yip Shing Tam KFBG (constructed wetlands), Wai-Keung Gary Yeung (architectural heritage).

This pilot study reframes wastewater treatment from the vantage of ecological community enablement. The bio-scientifically guided case action plan practically proposes for that the rural household to become the holder of solutions and self-provider of essential infrastructure services when they are lacking. For overcoming inertia and implementation gaps in resource planning the project so far produced three applied design probes for seeking a dialogue on ecologically and socially more responsive approaches to sewage management in a volatile environment. Ultimately the aim is to implement a scientifically informed eco-filtration installation on household level both as acceptance booster and technical demonstration (‘seeing is believing’).

The joint envisioning process with ecologists, architects, concern groups and residents has produced this blueprint for a self-contained, floating sanitation garden that confronts rising seawater levels while providing the assuring convenience of flush toilets. Currently this initiative seeks open-minded coastal residents to participate in a scientifically guided pilot trial.
Tai O fishing village is located on the eastern end of Lantau Island, separated only by a mountain range from Hong Kong airport.
Built along the forked Tai O River the village was renown for its shrimp paste, oyster industry, salt production and pirate base before its transition into a tourism destination as “Venice of Asia” (population: 1200).
Originally, the inquiry's intention was to explore small-scale, constructed wetland rafts to process excess nutrients from the outfall pipes.
Initially, the study entailed a funding application (pending) for a citizen science project towards monitoring the quality of Tai O's coastal waterways under the title TAI O WATER SCHOOL".
TAI O WATER SCHOOL proposes first a collective dye-tracing protocol where 20 selected unsewered household would simultaneously release a harmless fluorescent color agent into the waterways documented by drone footage.
TAI O WATER SCHOOL would indicate the pollution hot spots in Tai O waterways and implement a community-led remediation program with probiotic soil balls.
To address nutrients pollution preventively, URINE ECONOMIES proposed the agroecological reuse of source-separated urine: yet overcoming the longstanding mistrust among stilt house residents, changing people's toilet routines and establishing the social logistics proved to be a very tall order.
The probes revealed that stilt houses furthest away from the shore tend to be constructed far below drainage pipe levels and exposed to tides flooding, requiring either costly pumping systems or standalone, toilet/treatment boats as explored in these two sketches.
The structure of the floating ecofiltration toilet unit is informed by the water-borne aquaculture platforms of the local Tanka people (蜑家) who use recycled steel drums as pontoons.
The floating toilet with sanitation garden connects with an arched boat ramp to the stilt house by pivoting to the diurnal low and high tide.
Blackwater outfall piples
Blackwater outfall pipe during low tidewater, one sample of an estimated 150 stilt houses without sewer connection in Tai O fishing village
(photo: August 2020).
Blackwater outfall piples
The Wastewater Ecofiltration System is adopted from well-esteblished Permaculture practices and harnesses the natural dynamics of gravity, worm-metabolism, microbiome, evaporation and photosynthesis to upcycle excess nutrients (without any external energy input).
Overview of probes (provotypes)
The explorative research so far entailed three manifestation probes that evolved from awareness, intervention to activist design.

The mixed response among stilt house residents reveals a deeply entrenched risk aversion and indicates that access to (ecological) sanitation for informally built, semi-tolerated housing can be both a matter of human right as well as a privilege.

Why making a fuss about sanitation
when costly and tricky sewer connection
is on the dime of stilt house residents?

— Local social worker —

Why bother when strong tides wash the scum away
or fish are gobbling it up?

— Resident A —

Why care when scientists have declared
the water quality in Tai O as “Grade-A”?

— Resident B —

Why don’t you install this toilet raft first at the main pier
where it is needed foremost
rather than my own house?

— Resident C —

What are the shortcomings of this system?
Does it smell?
Does it leak?
Does it pollute people or water?

— Resident D —

Are you sure that you can secure a licence for this toilet raft
from the Marine Department?
There is just no precedent for this.

— Local boat builder —

What are we waiting for
when effluent excrements keep infesting our mangroves
which in turn require treatment with pesticides?

— Concern group member —