Sanitation · Choose and design blackwater treatment · sanitation-12

Plan safe handling of compost from toilets

Humanure can carry pathogens for a long time. WHO guidance on excreta use in agriculture uses time, temperature, pH and barriers to make it safe.

How

The safety rule comes first. Pathogens are destroyed only if compost holds at least 50 °C for 7 days (EcoSanRes, Stockholm Environment Institute).
Pile temperatures of 40 to 50 °C, typical of good composting conditions (Akvopedia), do not by themselves meet this rule.
If you cannot show 50 °C for 7 days, rely on storage time. At ambient temperatures up to 20 °C, 1.5 to 2 years removes most bacterial pathogens (EcoSanRes).
In hotter climates, about 1 year of storage may be enough (EcoSanRes).
Alkaline route: keeping material above pH 9 for at least 6 months kills most pathogens, for example by adding ash or lime (EcoSanRes).
Then manage the pile: carbon to nitrogen ratio near 25 to 1 and moisture 45 to 70% (Akvopedia, from the Eawag Compendium).
Use the squeeze test: a handful should feel like a wrung-out sponge, releasing only a few drops.
Keep a log of fill dates and, if you hot compost, daily temperatures, so you know which rule each batch met.
Treat compost that has met neither rule as not sanitised. Co-compost it further before use, apply it to fruit trees and ornamentals rather than root or leaf crops, and dig it in.
Wear gloves and protective clothing when emptying, and check local rules on using human excreta in food growing.

Safety: Wear gloves, boots and a mask when emptying chambers. Keep children and animals away from fresh material.