Friday, November 13, 2015

Hong Kong residents flush their toilets with sea water?

From the annals of "I did not know that" comes an article at C&EN by Deirdre Lockwood about chlorination of seawater-based wastewater:
In Hong Kong, about 80% of residents flush their toilets with seawater, thanks to a separate water distribution system set up in the 1950s. The approach conserves the city’s scarce freshwater resources, and has also been adopted by smaller communities like the Marshall Islands. As coastal populations and water demand rise, this idea may become more attractive elsewhere, though some researchers have worried about the release of potentially toxic by-products to coastal areas from treating seawater with chlorination. To the contrary, a new study suggests that the practice not only helps conserve freshwater but also may protect wildlife in marine ecosystems (Environ. Sci. Technol. 2015, DOI: 10.1021/acs.est.5b03796)....
I had no idea that Hong Kong residents flushed their toilets with seawater; makes a lot of sense.

Something like this would require massive infrastructure investment on the part of a municipality; I presume that inland cities could not bear the cost. It would be fascinating to know which cities on the east, west or southern coasts of the United States are actually close enough to a source of seawater to where this is a viable option. 


  1. Salt water can be pretty corrosive. And treating saline wastewater -- how does that work? The civil engineering must be different than here in the States.

    1. Yeah, I was thinking that it can't be good for the flushing mechanism. I'm guessing that residents of Hong Kong have gotten pretty good over the years at replacing chains and pipes. Until they switched to plastic maybe.

  2. @ English please! But, I agree!

  3. And the flip side:

  4. This may be an interesting proposal for the west coast, if drought conditions are expected to be the new normal in California.

  5. Heads aboard ships are flushed with seawater. Fresh water is very much a premium at sea.