Costa Rica Summer 2006

rainforest ecology and the natural history of costa rica

Aims and Objectives1) Engage with the natural environment of

Costa Rica

2) Study sustainability through the use of composting toilets

3) Experience the rich culture of Costa Rica

Natural Environment• Take exploratory

hikes in both the day and night

• Observe and identify plant and animal life

Rich Culture• Participate in a

homestay• Interact with the

locals

Sustainability• Gain a basic

understanding of how composting toilets work

• Understand the significance and ecological impacts of the composting toilets at Rancho Mastatal

Stop. Think. Recycle…

Sustainability through the Use of Composting Toilets

human feces?

“The idea of waste, of something unusable, reveals an incomplete

understanding of how things work. Nature admits no waste.

Nothing is left over; everything is joined in the spiral of life.”

- Sim Van der Ryn

A new way to recycle?• “Waste” → a resource • Human urine and feces decomposes

naturally into a nutrient-rich soil additive called humus

Or something so ancient and natural?

• The Food Cycle• Humanure and Asian Farmers• Humanure and Rancho Mastatal

On-Site Study• To explore the purpose and use of

the composting toilets at Rancho Mastatal

Methodology

1. Interview with Tim– To understand the history and

philosophy behind the use of composting toilets at Rancho Mastatal

– To understand how the toilets function– Comprised of 32 questions

2. Toilet Use Tally– To measure when and why either

composting or flush toilets were used at Rancho Mastatal

3. Toilet Preference Survey– To gain a sense of subject’s reactions to

and thoughts on using the composting toilets

Toilet Use Tally• Location

– Jeannie’s House or the Main House• Type of Toilet

– Composting or Flush• Purpose of Use

– #1 = urination; #2 = defecation or both• Time of Day of Use

– Daytime or Nighttime• Amount of Flushes

Finalized Tally Sheet

Research Question

Does the purpose of use or the time of day of use affect what sort of toilet is used?

Results

Location

1 2 3 4 5

0

10

20

30

40

50

60

Usag

e

Day

Graph 1.3 - Total Toilet Usage by Location

Jeannie's House (2 toilets)

Main House (2 toilets)

Type

1 2 3 4 5

0

5

10

15

20

25

30

35

40

45

50

Usag

e

Day

Graph 1.4 - Total Toilet Usage by Type

Composting (2 toilets)

Flush (2 toilets)

Purpose of Use

0

10

20

30

40

50

60

Usage

1 2 3 4 5

Day

Graph 2.3A - #1 Toilet Usage

Flush

Composting

0

5

10

15

20

25

1 2 3 4 5

Graph 2.3B - #2 Toilet Usage

Flush

Composting

Time of Day of Use

0

10

20

30

40

50

60

70

Usage

1 2 3 4 5

Day

Graph 3.3A - Daytime Toilet Usage

Flush

Composting

0

5

10

15

20

25

Usage

1 2 3 4 5

Day

Graph 3.3B - Nighttime Toilet Usage

Flush

Composting

Amount of Flushes

0

5

10

15

20

25

30

35

40

45

Usage

1 2 3 4 5

Day

Graph 4A - Toilet Uses and Flushes for #1 Use

Uses

Flushes

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Usage

1 2 3 4 5

Day

Graph 4B - Toilet Uses and Flushes for #2 Use

Uses

Flushes

Relevant Conclusions• Overall, flush toilets were frequented

more often than composting toilets• So flush toilets win? Not exactly…

Purpose of Use• Composting toilets were preferred

over flush toilets for defecation, while flush toilets were the most frequented option for urination

Possible Explanations• Composting Toilet Preference

– Stink factor– Toilet paper disposal– Sound privacy

• Flush Toilet Preference– Frequency of urination– Lesser need to flush

Time of Day of Use• The difference in usage between the

two types of toilets during the day was minimal

• At night, however, the difference is large, with composting toilets barely used and flush toilets used more often

Possible Explanations• Composting Toilets

– Scenic during the day– Dangerous at night

• Dark• Slippery trails• Less protected from the elements ( rain, creepy

crawlies)• Flush Toilets

– Convenient at all times– Safer at night

• Well-lit• Protected from rain• Easy to access, especially for middle-of-the-night uses

Weaknesses• Inconsistent tally sheets• Certain terms undefined

(daytime/nighttime, #1/#2)• Subject non-participation• Shifting subject pools• Assumed no other ways of relief• Non-statistical analysis of data

Future• Additional research needed

– Statistical analysis– Other factors (type and design of the

composting toilets)• Possible considerations for future

composting toilets– Location relative to the houses– Safety and convenience of access

Composting toilets make sense

But are they practical?

“It is possible to quit putting our so-called bodily wastes where they don’t

belong (in the water) and to start putting them where they do belong (on the land). When waste is used, a liability becomes an asset, and the very concept of waste disappears.”

- Sim Van der Ryn