← Field Notes Rig Systems No. 19

Build log: the composting toilet

No black tank. Here's the actual trade.

The toilet is the upgrade people ask about most and admit to least.

How they work: they separate liquid from solid. That separation is the entire trick — mixed waste is what smells. Solids go into a chamber with a dry medium (coco coir or peat), a small fan vents continuously, and the result is genuinely not offensive.

What you gain: no black tank, no dump station, no sewer hose. No water per flush — meaningful when you're hauling every gallon. Freedom to stay put longer; the limit becomes food and water, not tank capacity. No freeze risk in a black tank.

What you trade: the liquid emptying routine. Solids periodically. A small fan on continuous 12V — tiny, but it's a 24/7 load. Higher upfront cost. And venting has to be installed properly or odor control fails.

The honest verdict: for full-time use, most people who switch don't go back. For occasional weekends, a standard toilet and a dump station is simpler and cheaper.

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