其實而家淡水咁充裕既情況下
根本無需要用咸水沖廁
https://www.quora.com/Why-is-sea-water-not-used-for-domestic-purposes-at-least-for-flushing-in-toilets
個BEST ANSWER講得好好
(1) significant infrastructure (pipes, pumps and so on) would need to be installed
基建貴,用錢起咸水喉不如用錢起淡水喉
(2) seawater is more corrosive on pipes and fittings
維修費貴,成日爆咸水喉,馬桶個D又會整D好易壞
(3) toilets represent a small fraction of water use.
沖廁水只係用好少水