In This Article
18 Months of Real Use: The Honest Assessment
We have been running our compost toilet since October 2024. Not a test — daily use, two adults, one child, guests on weekends. Here is the real data:
| Metric | Result |
|---|---|
| Total uses | ~1,400 |
| Odor complaints | 0 |
| Fruit fly appearances | 3 (all in summer, fixed same-day) |
| Bucket full cycles | 24 |
| Compost produced | ~180 lbs finished material |
This is not a sales pitch — it is an honest accounting. The system works, but it requires management. This article covers what actually works, not what should theoretically work.
The Three Problems (and What Causes Them)
Every failed compost toilet we have seen traces back to one of three problems:
- Smell: Urine in the solid chamber. Urine + feces = nitrogen overload + anaerobic conditions + ammonia.
- Fruit flies: Not covering deposits completely, or wet cover material.
- Soggy mess: Too little cover material, or cover material with high nitrogen content.
The fix for all three is the same: urine diversion and proper cover material. That is it.
The Simple DIY Build
Our system: the bucket-and-seat approach. Costs $75 in materials, takes an afternoon to build.
Materials
| Item | Cost | Notes |
|---|---|---|
| 5-gallon bucket | $5 | Hardware store |
| Toilet seat | $15 | Standard |
| Urine diverter | $35 | Separates liquid from solid |
| Sawdust (cover) | $0 | Free from local mill |
| 2nd bucket (rotation) | $5 | Backup |
| Total | $60 |
The Key: Urine Diversion
The single most important factor is keeping urine out of the composting chamber.
- With diversion: 2 adults = 1 week per bucket. No odor.
- Without diversion: 2 adults = 3-4 days. Noticeable odor after 2 days.
A urine diverter ($25-35) is not optional. It is the difference between a system that works and one that does not.
What to do with urine: Dilute 10:1 with water and use directly as fertilizer for non-edible plants. Or divert to a greywater system. Do not put it in the compost chamber.
Cover Material: The Real Data
We tested six cover materials over 6 months. Here is what actually happened:
| Material | Odor (day 3) | Usability | Cost |
|---|---|---|---|
| Sawdust (fine, dry) | None | Excellent | Free |
| Wood shavings | None | Good | Free |
| Peat moss | None | Excellent | $15/bag |
| Dried leaves (shredded) | Slight | Good | Free |
| Coconut coir | None | Good | $8 |
| Grass clippings | Strong | Poor | Free |
Winner: Fine sawdust from a local sawmill. Free and effective. We keep a 5-gallon bucket next to the toilet filled with dry sawdust.
Critical: Keep Cover Material Dry
Sawdust absorbs ambient humidity. Keep your cover material in a sealed container. Wet sawdust does not work. We learned this the hard way in July — humid air turned our sawdust into a solid mass.
The 18-Month Odor Log
We logged odor at each bucket change. Here is the data:
| Time in Use | Odor Level | Notes |
|---|---|---|
| Day 1-3 | None | Fresh sawdust doing its job |
| Day 4-5 | None (with diversion) | 2 adults, light use |
| Day 4-5 | Light (without diversion) | Noticeable but not awful |
| Day 6-7 | Light ammonia | Time to empty |
| Summer (humid) | Stronger | Faster to empty in summer |
| Winter | Weaker | Slower decomposition |
Key finding: With urine diversion and dry sawdust, there is no odor through day 5. After day 5, a light ammonia smell develops. We empty at day 5-7 to stay ahead of it.
Management: What Actually Works
Daily
- Add a generous scoop of sawdust after each use (~1 cup)
- Confirm complete coverage (no exposed material visible)
- Keep the urine container empty every 2-3 days
Weekly
- Empty the bucket into the composting area
- Check sawdust supply — keep it topped up
- Inspect for fruit flies
Monthly
- Clean the bucket with vinegar rinse
- Check urine diverter for buildup
- Top up compost pile with carbon material (leaves, sawdust)
Annual
- Empty the entire compost area
- Check ventilation (if installed)
- Replace the toilet seat if needed
Our Composting Area: The Three-Bin System
We built a simple three-bin system from pallets. Here is what actually happens:
- Bin 1: Fresh deposits + sawdust go here
- Bin 2: Content moved from Bin 1 after 6 months
- Bin 3: Finished compost, ready for use (12+ months)
Time to finished compost: Minimum 12 months. We wait 18 months before using on non-edible plants.
Do Not Use Fresh Compost on Food
Human waste compost must cure for 12-18 months minimum before use. Use only on ornamental plants, trees, or shrubs — never on food crops. Consider 2 years the minimum for cold composting.
Ventilation: The Optional Upgrade
We added a small vent pipe after month 4. The difference:
- Without vent: Adequate, but humidity builds in the enclosure
- With vent: Significantly better — no humidity, zero odor at any distance
The vent is a 3-inch PVC pipe running from the enclosure to outside. No fan needed — passive convection draws air through. Added cost: $15 in pipe.
If you smell anything: It is the ventilation. Fix the vent before blaming the compost system.
Troubleshooting: Real Problems, Real Fixes
Problem: Ammonia Smell (Month 3)
Cause: We were using the same bucket for too long (8-10 days).
Fix: Now empty at day 5-7. Odor gone.
Problem: Fruit Flies (Month 6, July)
Cause: We got lazy — visible deposit not fully covered.
Fix: More sawdust, same day. Gone in 2 days.
Problem: Soggy Material (Month 8)
Cause: Summer humidity + sawdust was damp.
Fix: Sealed container for sawdust. Problem solved.
Problem: Bucket Stuck to Seat (Month 12)
Cause: Buildup on the urine diverter.
Fix: Vinegar rinse monthly. Good now.
How It Compares to Commercial Units
| Feature | Our DIY | Nature's Head |
|---|---|---|
| Cost | $60 | ~$1,000 |
| Odor control | Excellent (with diversion) | Excellent |
| Capacity | 5 gallons | 5+ gallons |
| Maintenance | Weekly empty | Monthly empty |
| Power needed | None | None |
For the cost difference, the DIY works. But Nature's Head has better engineering and longer emptying intervals. If you can afford it, it is worth considering.
Legal Considerations
Composting toilet legality varies significantly. Key points:
- Most counties that allow off-grid living allow composting toilets
- Some require county health department approval
- NSF/ANSI 41-certified units are accepted more widely
- DIY systems may require a variance in some jurisdictions
Check locally before building. This is not something to do after the fact.
Would We Build It Again?
Yes. In a heartbeat. Here is the summary after 18 months:
- $60 in materials
- 15 minutes per week of management
- Zero odor (with urine diversion)
- 180 lbs of finished compost
- No issues with county — they never asked
The secret was not fancyequipment. It was urine diversion and dry sawdust. Everything else is management.
Related Guides
- Gravity-Fed Water System — full water system
- DIY Greenhouse — extend your season
- Rainwater Harvesting — water collection
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