Composting Toilet Designer.
Composting Toilet & Humanure Designer
Off-grid sanitation that produces fertility instead of waste. Bucket-system sizing, cover material, decomposition timing, what's legal where.
The bucket system (Joseph Jenkins method)
The simplest, cheapest, and arguably most reliable composting toilet. A 5-gallon bucket sits inside a wood box; a toilet seat tops it. Each use is followed by a generous scoop of cover material (sawdust ideal). When full (~3-5 days for two people), the bucket is emptied into a primary outdoor compost bin where it sits for 1-2 years before use.
| Stage | Detail |
|---|---|
| 1. Bucket use | 5-gal bucket with toilet seat over wood box; sawdust scoop after each use |
| 2. Bucket emptied to bin | Outdoor primary compost bin (~1 cubic yard); each emptying covered with hay/straw to deter flies + smell |
| 3. Hot compost phase | ~2-4 weeks of thermophilic decomposition (130-160°F) — kills pathogens. Critical step. |
| 4. Curing | 1-2 years at ambient temperature before any use. Gives full pathogen die-off margin. |
| 5. Application | Fruit trees, ornamentals — NOT directly on root vegetables intended for raw consumption |
Why the cover material matters
Cover material does three critical jobs:
- Suppresses smell. Properly covered, a bucket toilet has no odor — less than a flush toilet because no decomposition is happening anaerobically in water.
- Excludes flies. Visual barrier prevents fly oviposition.
- Provides carbon for composting. Human deposits are nitrogen-rich; the cover material is the carbon balance for proper hot composting (target C:N ~25-30).
Inadequate cover = smell + flies. Always over-cover, never under-cover.
Pathogen die-off timeline
| Pathogen | Die-off conditions |
|---|---|
| E. coli | Killed in days at 122°F+ thermophilic compost |
| Salmonella | Killed in hours at 131°F |
| Roundworm eggs (Ascaris) | The most resistant; killed in 24 hr at 131°F or 6+ months curing at ambient |
| Cryptosporidium | Killed in days at 131°F+; or 1+ year ambient |
| Hepatitis viruses | Killed at 131°F in days |
The 1-2 year curing requirement isn't about most pathogens — it's about Ascaris eggs and similar resistant organisms. Hot compost phase (3+ days at 131°F+) plus 1-year curing has been shown safe in extensive testing.
Legal considerations
| Jurisdiction type | Status |
|---|---|
| Most US states | Composting toilets legal; building/health code varies. Many require commercial NSF-41 certified systems for permitted dwellings. |
| Off-grid + remote | Often de facto unregulated below state attention; common at hunting camps, remote homesteads |
| Permitted residences | NSF-41 certified commercial unit usually required (Sun-Mar, Nature's Head); DIY bucket usually not permittable |
| Municipal / urban | Generally banned without special permit; some progressive jurisdictions (Portland OR, San Francisco) have begun permitting |
| Application of compost | USDA NOP: humanure NOT permitted on certified organic produce. State greywater rules may apply. |
Where to apply finished humanure
| Application | Status |
|---|---|
| Fruit trees, ornamental beds | ✓ Standard application |
| Berry shrubs | ✓ OK with surface mulch separation |
| Vegetable beds (heating crops: corn, tomatoes, etc.) | ✓ With soil mixing + 6-month gap before harvest |
| Root crops eaten raw (carrots, beets, radish) | ✗ Avoid direct application; risk too high |
| Leafy greens eaten raw | ✗ Avoid; surface contamination risk |
| Non-food: woodlot, pasture buffer, lawn under trees | ✓ Anywhere |
| Grain crops (cooked food) | ✓ Standard |
Free under CC BY 4.0. Cite as "OAT Composting Toilet Designer (openagriculturetechnology.com)". Methodology drawn from Joseph Jenkins's "The Humanure Handbook" and WHO sanitation guidelines.