Check a humanure compost pile daily with a long-stem thermometer pushed to the core and to the coolest accessible point, and count the batch as heat-treated only when both read 55°C or more for at least 3 consecutive days. Do not judge by hand or by pulling out a stick and gripping it, because touch cannot separate 45°C from 60°C and means handling material from human waste.
Part of Composting Toilet Systems
Monitoring is the routine of measuring a compost pile’s temperature and condition so that you know whether it has reached the heat that kills human pathogens. A pile that is not measured has to be treated as untreated.
What To Measure, And Why Twice
The parent page says to insert a thermometer into the centre of the pile and gives the bands: below 40°C too small, dry or carbon-heavy; 40-55°C mesophilic, with pathogen kill incomplete; 55-65°C thermophilic, the target; above 70°C too hot, turn it. The centre is the best-case reading, and the outer shell of a bin is the cool zone (Thermophilic Decomposition). So measure two places:
- The core: about the middle of the mass.
- The coolest accessible point: about 30 cm in from a corner or the bottom edge, away from the bin wall.
The batch is counted as treated only when both reach 55°C or more on 3 consecutive days (Pathogen Kill Requirements).
What You Need
- A long-stem thermometer reading at least 70°C. A compost thermometer, a dial oven or dairy thermometer on a stem, or a salvaged metal-stem dial thermometer. A clinical (fever) thermometer tops out too low to be useful.
- A tube or pipe you can push into the pile and leave, so you do not need to disturb it each day. A closed-end pipe works; lower the thermometer into it on a cord.
- A log sheet by the bin, and a pencil.
- A way to check the thermometer: it should read 0°C in a mix of melted ice and water. If it is off, record the correction and apply it to each reading.
Method: A Daily Reading
Step 1: Position the tubes when you start a new batch or layer: one near the middle, one 30 cm in from the corner.
Step 2: Read at the same hour daily for the first 3 weeks, then weekly. Write the date, core, cool-point and weather.
Step 3: Count. Mark each day on which both readings are 55°C or more. The count starts at day 1 and resets to 0 if either falls below 55°C.
Step 4: React. If the core is above 70°C turn or open the pile to cool it, with protective gear. If the core stays below 40°C, add nitrogen (urine, green material), moisture or bulk. If it was hot and has cooled, the active phase is over.
Worked Example: A Log Sheet
| Day | Core | Cool point | Both 55°C or more? |
|---|---|---|---|
| 1 | 42°C | 28°C | No (count 0) |
| 5 | 58°C | 38°C | No (count 0) |
| 6 | 62°C | 49°C | No (count 0) |
| 7 | 64°C | 56°C | Yes (count 1) |
| 8 | 63°C | 57°C | Yes (count 2) |
| 9 | 60°C | 55°C | Yes (count 3) |
Treated at day 9: the count reached 3 consecutive days. The year of ageing starts from there, and the date goes in the maintenance log (Maintenance Schedules). All readings here are illustrative.
Reading The Rest Of The Pile’s Progress
- Volume: a hot pile shrinks; Compost Maturity gives 30-50% for ordinary compost.
- Smell: sharp ammonia early, then earthy.
- Moisture: damp like a wrung-out sponge, never dripping.
- Finished: dark, crumbly, soil-smelling, with no recognisable waste. The parent page says the same, and it proves nothing about pathogens by itself.
Why Not The Hand Or Stick Test
The first-month page and the compost-maturity page both describe feeling the heat with a bare hand or by gripping a stick pulled from the pile. For ordinary compost that is acceptable. For humanure it puts your skin on human waste, and it cannot tell 45°C from 60°C, the difference that decides whether the eggs die. Use the thermometer.
Common Mistakes
- Reading only the core. It is the warmest spot.
- A thermometer that cannot reach 70°C. It will peg out.
- Not recording the date the count started. You cannot date the year.
- Disturbing the pile daily to probe it. Leave the tubes in.
Safety
Opening or probing a pile of human waste exposes you to pathogens and spores
Wear gloves and a cloth over the nose and mouth; keep the probe dedicated and wash it with soap and hot water after use; do not touch your face; wash hands afterwards. Do not turn fresh humanure without protective gear. A very hot pile can burn skin and, in a big stack of dry material, can ignite; keep flames away.
What’s Next
- Learn next: Safe Application in Gardens — what a recorded batch may be used for
- Combine with: Compost Bin Construction — the bin the tubes go in