Cold Water
Overview
Cold water (Korean: 찬물) is a general term for water at a temperature lower than room temperature (about 20–25°C); in everyday usage it often refers to drinking water in the vicinity of 0–15°C. More than a simple beverage, it is a subject that connects broadly to thermodynamics, physiology, food culture, and industrial cooling, and especially in East Asia including Korea, health conventional wisdom such as "drinking cold water gives you a stomachache" is strongly entrenched, so the gap between scientific evidence and folk belief is frequently discussed.
Main Content
Definition and Physical Properties
At 1 atmosphere, water has its freezing point at 0°C and its boiling point at 100°C. Cold water generally means between just above 0°C and 15°C, while chilled water, cooling water, and ice water each define different temperature ranges depending on use. Water exhibits anomalous expansion, reaching maximum density at 4°C; thanks to this, ice floats on water and lakes freeze from the top down, allowing aquatic ecosystems to endure the winter. Its specific heat is very large at about 4.18 J/g·K, making cold water an excellent cooling medium that absorbs heat, and as the temperature falls, viscosity increases and evaporation slows. These properties form the basis for the design of cooling water, air conditioning, and food preservation.
Physiological Effects
When a person drinks water colder than body temperature (about 36.5°C), the body expends energy to make up for that heat. Studies have reported that drinking 500 mL of cold water produces roughly 20–30 kcal of additional energy expenditure, but it is difficult to see this as directly leading to weight loss. Regarding the rate of gastric emptying, results are mixed, with some showing that cold water slows emptying and others showing no significant difference. On the other hand, the evidence that drinking cold water during exercise suppresses the rise in core body temperature and helps quench thirst and maintain performance is relatively consistent, and it is widely recommended in sports settings. Cold showers or cold water immersion (cold plunge) can activate the sympathetic nervous system and increase norepinephrine secretion, potentially affecting alertness and mood improvement. However, for people with irritable bowel syndrome, functional dyspepsia, or exercise-induced asthma, cold beverages may trigger symptoms or irritate the airways, so individual differences are large.
Health Conventional Wisdom and Scientific Evidence
The claims that "cold water after a meal interferes with digestion" and that "cold water constricts blood vessels and strains the heart" are generally weakly supported. For healthy adults, it is difficult to find consistent evidence that cold water intake causes meaningful harm to digestive function or the cardiovascular system. The conventional wisdom that "lukewarm water is better for health than cold water" likewise lacks research demonstrating a clear advantage. Ultimately, whether cold water is good or bad for the body depends less on the water temperature itself than on an individual's gastrointestinal sensitivity, the drinking context, and total fluid intake.
Cold Water in Culture and Daily Life
In Korea, the chilled water or barley tea served in restaurants, the cold-water function of water purifiers, and the culture of ice water in summer are all natural. Japan likewise serves cold water (ohiya) as standard in restaurants, while China has long placed importance on the tradition of baekaesu (白開水), boiled water left to cool. Regional differences are pronounced, with some parts of Europe preferring room-temperature water and the United States preferring ice water. As folk remedies, cold water rubbing, cold baths, and cold water therapy have been handed down since long ago, and in modern times they are being reexamined in combination with wellness culture.
Industrial and Everyday Applications
Cold water is a core cooling medium for power plants, semiconductor processes, and data centers. Its range of uses is broad, including food storage, refrigerated and frozen logistics, firefighting water, concrete curing, and district cooling (using deep seawater or seawater).
Latest Trends
In 2024–2025, cold plunges and ice baths became representative trends of the wellness industry, and sports science and mental health research on them is active. At the same time, as AI data centers proliferate rapidly, demand for cooling water and the burden on water resources grow, bringing attention to immersion cooling, waste heat recovery, and cooling water reuse technologies. As heat waves become more frequent due to climate change, demand for cooling water and for responses to heat-related illness has also increased, and in the water purifier market, direct-flow cold/hot water purifiers and the microplastics debate continue. Research on cold water intake and energy metabolism, thirst relief, and muscle recovery also continues to be published.
Related Topics
- [[물]]
- [[수분 섭취]]
- [[얼음]]
- [[온수]]
- [[콜드 플런지]]
- [[데이터센터 냉각]]