Different assets have varied approaches to the disposal of human waste products . The ones I am familiar with have all products are disposed of directly into the sea via a caisson / pile. Makes for a real simple design. Though, even then you can get it wrong:
- Tieing the individual septic piping together above the caisson level. That’s a good way of giving a downstairs user a scare (and a septic shower) when a higher user flushes to dispose of waste.
- Tieing in the septic piping into process drain piping. That could cause backflow of any evolved gas from the drains into your toilets. In the old days, this has caused accidents initiated by smoking customers. And smells up the process area.
- Designing too short the septic caisson / pile . It’s supposed to discharge below sea level, people! You might have a voyeuristic streak, but watching other people’s disposal products get dropped above you while you are working on the lowest deck (sea deck in my parlance) does not a happy camper make. Esp. if you are down wind.
I have worked on a project that required a full septic system. There was a bit of head scratching there. First time I thought of picking up a civil engineering book. Concept’s easy, have a tank to ferment solid products, send the water to the sea. But who does the septic tank cleaning? Indah Water?
Batfish Racha Yai Phuket
Wata - Malaysian Oil and Gas Engineer 
can you discrip more on how excatly dispose of human waste products on offshore.
tq
Fadhil: sure. Hole, ocean, fish, fisherman… getting the idea?
the sea is your toilet