Toilet options

Compact, self-contained and easy to remove; it uses little/no system water depending on flush design. Small capacity means frequent legal dumping, but international service is straightforward.

Composting/diverting and dry flush

These can eliminate a black tank, but urine handling, consumables, ventilation, truthful composting time and legal disposal still matter. Dry-flush systems trade plumbing for cartridges and waste volume.

Portable chemical and black tank

Portable toilets are inexpensive but small. Traditional RV toilets offer familiar use and bigger capacity, yet require a black tank, roof vent, 3 in-class drainage, dump hardware and legal stations.

Design impact

Toilet choice changes fresh demand, grey/black capacity, floor penetrations, venting and storage. Decide it before tank layout, not after cabinetry.

Build rule

If you cannot reach it, isolate it, drain it and explain its pressure/temperature or water-quality job, it is not ready to hide behind a wall.

CHAPTER CHECK

• I can explain the purpose and failure mode of each item in this chapter. • I know which manufacturer limit or water-quality claim controls my choice. • I added the valve, access, drain, measurement or maintenance task to my drawing/checklist.