In order to make the most efficient use of the city's limited supply of potable water, the vast majority of Hong Kong's toilets are plumbed to use seawater instead of freshwater. This practice dates back to the early days of the British colony, when it was apparent that the city's limited water supply could not fulfill the needs of the quickly rising population at the time. Since then, the practice has remained in place.
Flushing toilets with seawater eventually became the standard, and it is estimated that only about 5 percent of toilets in Hong Kong still utilize freshwater.The usage of saltwater in toilet flushing can be attributed to a variety of different factors. To begin, it is a resource that is readily available; as Hong Kong is encircled by water, there is no dearth of water that may be utilized.
Second, it is better for the environment than utilizing freshwater since using saltwater rather than freshwater helps to preserve a resource that is extremely valuable. And finally, it is economical. The use of saltwater rather than freshwater, which must be pumped in from a greater distance, is far less expensive.
There are a few disadvantages associated with flushing toilets with seawater, despite the fact that this method offers several advantages. The smell of salt, which can sometimes be detected in restrooms that use seawater, is the most glaring example of this problem. In addition, the salt component of seawater can be corrosive, which means that it can harm toilet fixtures and fittings over time if it is allowed to sit there.
Because of these factors, some individuals choose to flush their toilets with freshwater rather than saltwater, despite the fact that the former is more costly and the latter is less kind to the environment.