Not so straightforward to use seawater

Before we follow Hong Kong and use seawater to flush toilets, we should find out the costs and benefits, and why the city resorted to using seawater (How to save water: Use seawater by Mr Yeo Chee Kean; Feb 24).

If we use seawater, we will need to change the pipes because our pipes will not withstand the corrosive effect of salt water. The cost of this would be high.

As Singapore's weather is warm, the formation of salt crystals inside the pipes would be a problem, and costly equipment would be required to clean it up.

Additional infrastructure would also be needed to bring seawater to households.

Furthermore, the seawater would need to be treated after being flushed away.

Removing the salt and discharge is energy intensive. What would we do with the salt afterwards?

Hong Kong uses seawater for flushing because it is short of fresh water alternatives.

This has been done since the 1950s, and a dual plumbing system is in place.

Hong Kong's use of seawater is also not free - large investments and resources are needed to extract, transport, supply and treat the water.

Like Singapore, Hong Kong is also increasingly using reclaimed water and aiming for 100 per cent water self-sufficiency, rather than rely on China for water.

This is a more sustainable development.

Francis Cheng

A version of this article appeared in the print edition of The Straits Times on March 01, 2017, with the headline 'Not so straightforward to use seawater'. Print Edition | Subscribe