The reason why smokers drink water after smoking is to prevent dehydration as well as fix dry mouth or xerostomia which is caused by nicotine, which reduces saliva.
Drinking water after smoking also helps to flush out nicotine and other toxins and also soothes the throat and eases cravings for nicotine by replacing sugary drinks which intensify smoking urges.
Keeping hydrated is also an easy way of mitigating the drying effects of smoking and improve the smokers overall comfort.
Smoking reduces production of saliva and makes your mouth feel dry and sticky, and the water helps to re-moisten the mouth.
Nicotine is also water soluble, so drinking water after smoking helps the body eliminate the nicotine and other chemicals faster.
Hot water or tea can also thin mucus and soothe your throat when it's irritated by smoke.
Remaining hydrated also helps to manage withdrawal symptoms like headache and it's also a healthy replacement for sugary drinks which can also increase cravings for cigarettes.
Proper and adequate water intake also helps keep the lungs lubricated and makes it easier to clear out mucus and irritants.
Smoking itself can be dehydrating, which makes remaining hydrated more crucial although you should always stay hydrated.
Water also helps to ease headaches, constipation, and foggy feelings that is often associated with nicotine withdrawal.
Staying hydrated with plenty of water also supports digestion, focus and your general body functions, which are all beneficial when trying to quit smoking and beneficial for your overall health.