When someone is severely dehydrated, plain water alone might not fully quench thirst or restore balance in the body effectively. Here's why:

1. Electrolyte Imbalance

Severe dehydration often involves the loss of electrolytes like sodium, potassium, and chloride, which are critical for maintaining fluid balance and proper cell function. Drinking plain water without replenishing electrolytes can dilute the remaining electrolytes in your body, potentially worsening the imbalance.

2. Delayed Rehydration

Plain water doesn't contain the necessary components to quickly replace lost electrolytes. Rehydration solutions or drinks with added electrolytes (like oral rehydration salts or sports drinks) are often more effective in severe cases.

3. Mechanism of Thirst

Thirst is not only triggered by a lack of water but also by a high concentration of solutes (like salt) in the blood. Drinking plain water can reduce the sense of thirst temporarily but might not address the underlying electrolyte deficit, leaving the body still "craving" balance.

4. Body’s Absorption Rate

Electrolytes like sodium help the body absorb water more efficiently. Plain water may pass through the digestive system without being absorbed as effectively, particularly when the body's electrolyte balance is significantly off.

What to Do for Severe Dehydration:

• Use oral rehydration solutions (ORS) containing a mix of water, salts, and sugar, which enhance water absorption.
• Include foods or beverages that naturally contain electrolytes, like coconut water or broth.
• In extreme cases, medical intervention (such as intravenous fluids) may be necessary.