There are mainly two reasons for not pouring water into an smoking tray: practical impacts and negative implications.
Throwing cigarette ashes into a water-filled smoking tray will worsen the already smoke-laden indoor environment. As we all know, modern cigarettes are usually fitted with a filter at the end to reduce harm and enhance smoking comfort. After a cigarette burns, this filter accumulates a great deal of harmful substances, including tobacco oil and nicotine, with concentrations even higher than those in an entire cigarette. If a cigarette butt is discarded in a water-filled smoking tray, the remaining harmful substances will dissolve in the water. If we neglect to dispose of this water, the dissolved harmful substances will evaporate and disperse into the air, deteriorating indoor air quality.
Moreover, when a cigarette butt soaks in water, it changes color and gives off a strange, unpleasant odor. The mixture of water, butts, and ashes is not only disagreeable but also unsightly. When hosting friends, placing such an smoking tray on the table may leave a poor impression.
Another practical issue is that it becomes hard to clean. When butts and ashes are left in a water-filled smoking tray, too little water will make the ashes dissolve and stick firmly to the smoking tray. Too much water, on the other hand, can easily spill during cleaning, adding to the cleaning hassle. Smoking trays are shallow and small, so pouring water into them often leads to overflow. Hence, dry smoking trays are more suitable for smokers. "Never put water in an smoking tray" is a common joke among smokers. It means that if you put water in the smoking tray, you won't be able to smoke the leftover cigarettes in it when you feel the urge. Online, this phrase is also used to describe people who are down and out with no way out.
Long-term smokers, when still craving a smoke after finishing one, often think of the butts they left behind. Some partially extinguished cigarettes still have a lot of smokable tobacco left. If the smoking tray has water, those cigarettes become unsmokable. But if the smoking tray is dry, those cigarettes can address the immediate "urgent need" and satisfy the craving. As you can imagine, this scenario means leaving a way out for oneself; there will always be times when one needs to cope with something.
In fact, not pouring water into an smoking tray carries a deeper meaning. One implication is that our actions should not be too extreme. Pouring water into an smoking tray symbolizes completely extinguishing the butt, making it impossible to relight. This also reflects a principle in how we handle things: never block our own path. The saying "Leave a way for others, so we can meet again someday" embodies this principle.
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