Drinking water in the morning is good, but not all types of water are suitable. Here are four types of water you should not drink upon waking up.
Stale boiled water
After boiled water has been left standing for a while, its nitrogen-containing organic compounds continuously break down into nitrites. This process is especially accelerated in boiled water that has been stored for too long and inevitably contaminated with bacteria, leading to even more nitrite formation. Consuming such water causes nitrites to combine with hemoglobin, which can impair the blood's ability to transport oxygen.
Therefore, water that has been sitting in a thermos for days, the remaining water from multiple boilings, or water that has been boiling on a stove for a long time should not be consumed, as its composition has changed. You should drink water that has been boiled once and not stored for more than 24 hours. Additionally, bottled and桶装 (barreled) purified and mineral water should not be stored for too long. Large bottles or barrels of purified and mineral water should not be consumed after 3 days.
Salt water
Some people believe drinking light salt water is beneficial to health and therefore drink it upon waking. This is a mistaken belief. While it is true that drinking light salt water can be beneficial, for example, for replenishing fluids after sweating in the summer, it is not only unhelpful but also a harmful practice for rehydrating in the morning.
Physiological research indicates that during a full night's sleep, a person does not drink any water, yet breathing, sweating, and urination continue, leading to significant water loss. Upon waking in the morning, the blood is in a concentrated state. Drinking a certain amount of plain water can quickly dilute the blood, correcting the hyperosmolar dehydration that occurs overnight. Drinking salt water, on the other hand, would worsen this hyperosmolar dehydration, making one feel even more thirsty. Furthermore, blood pressure typically peaks in the morning, and drinking salt water can drive it even higher, posing a health risk.
Beverages
The first glass of water in the morning should ideally not be commercially available drinks like juice, cola, soda, coffee, or milk. Carbonated drinks like soda and cola often contain citric acid, which accelerates calcium excretion during metabolism, reducing the calcium content in the blood. Long-term consumption can lead to calcium deficiency. Other beverages have a diuretic effect, so drinking them in the morning not only fails to effectively replenish the body's needed fluids but also increases the body's demand for water, potentially leading to dehydration.
Fruit juice, milk, and coffee are also not suitable as the first drink in the morning because they do not provide the water the body needs most at that time. They also force the digestive and absorption systems to work while the body is still dehydrated, which is not conducive to health.
Tap water
Some people have the habit of turning on the tap first thing in the morning and drinking a glass of tap water. This is incorrect. The tap water and pipes have been stagnant all night. The water and the metal pipe walls and faucet chambers undergo a hydration reaction, creating metal-contaminated water. Furthermore, residual microorganisms in the tap water can multiply. This water contains a large amount of substances harmful to the human body and may even harbor *Legionella*, an acute respiratory pathogen that threatens human health. Therefore, the tap water that flows out first in the morning is undrinkable stagnant water. If you have this habit, please correct it immediately to avoid damaging your health.