Bangkok's salty water: Safe to drink?

Bangkok tap water has tasted salty recently. The Metropolitan Waterworks Authority (MWA) explains when you need to worry.


Worth its salt?

For those who don't mind its brackish taste, filtered tap water in Bangkok is safe to drink — at least to some extent


Arusa Pisuthipan

Tap water in many parts of Bangkok, even after being filtered, has never before tasted so salty and unpalatable — so much so that many households have opted to purchase bottled drinking water. And the cause is clear. A few weeks ago, the Metropolitan Waterworks Authority (MWA) announced an unusually early intrusion of seawater into its pumping station, which threatened the production of tap water in urban neighbourhoods. According to the MWA, salt water usually reaches the MWA’s Sam Lae pumping station in the Muang district of Pathum Thani province — the station that feeds fresh water to the MWA’s tap water production facility in the eastern part of Bangkok — from April to May. The problem often resolves by itself in the rainy season, which usually begins in May or June.

But this year the dry season started early and is expected to last longer. Salt water has been evident in the pumping station since early February. Believed to be the worst in the last 100 years, this early and lengthy intrusion of salt water has affected all of Bangkok, except the Thon Buri area. People in the aforementioned zones have probably noticed a more brackish taste to the water that comes from their household filters. MWA governor Thanasak Watanathana, however, said tap water is safe to drink.... 

..Seawater contains around 3.5% salt, which is water-soluble. Most household water purifiers sift only non-water soluble particles. Therefore, tap water from many standard filters will still have a salty taste. Boiling water will not help, either. The only type of water filter that can purge sodium and its brackish taste is one with reverse osmosis technology. Reverse osmosis is a water purification technology that uses a semi-permeable membrane which filters water-soluble particles. Distilling water can also rid it of its brackish taste, yet this method is quite costly. 

Thanasak said the intrusion of seawater should be resolved once the rainy season arrives, because there will be more fresh water to flush salty water from the production system. In the meantime, Somsri recommended consumers opt for FDA-approved bottled drinking water, especially if they find the brackish taste unbearable.

There is no need for people to be over-anxious. If you do not mind the taste, just do what you normally do, because in terms of the tap water’s hygienic standard, it is pretty much the same. It is just the taste that matters. But if you suffer from certain chronic diseases such as kidney- or thyroid-related illnesses, that’s another story, and it is advisable that you be more careful. Drinking bottled water might be a good way to go for now.

About the author

Writer: Jon Fernquest
Position: Online Writer