The concept of “hot” water temperature can vary depending on the context (e.g., human comfort, cooking, industrial use), but here’s a detailed breakdown of what temperatures are generally considered hot in Celsius.
1. Human Comfort and Safety
When considering comfort and safety for human interaction, water is usually considered “hot” when it reaches 40°C (104°F) and higher. At temperatures above this, the risk of burns or discomfort increases.
- Warm water (about 30°C – 37°C): This is often considered comfortable or mildly warm for activities like washing hands or bathing.
- Hot water (about 40°C – 49°C): Water at this temperature range feels uncomfortably hot for most people and can cause burns with prolonged exposure.
- Very hot water (50°C and above): Water at 50°C or higher can cause instantaneous burns if you come into direct contact with it for even a few seconds.
For reference:
- At 40°C: Water feels very warm but typically doesn’t cause injury with short exposure.
- At 50°C: It feels uncomfortably hot and can cause second-degree burns if exposed for more than a couple of seconds.
- At 60°C: Severe burns can happen almost instantly with direct contact.
- At 70°C and above: These temperatures are typically dangerous, and burns can occur immediately upon exposure.
2. For Cooking
Certain cooking applications require hot water but are less concerned with the safety thresholds for humans.
- Hot water for cooking: Boiling water is typically at 100°C (the boiling point of water at sea level), which is considered extremely hot. However, for certain culinary techniques like blanching vegetables, you may use water that’s 80°C – 90°C, which is still very hot but below boiling.
- Boiling point (100°C): Water at 100°C is used for boiling foods (pasta, vegetables) and making hot beverages like tea or coffee.
- Simmering (85°C – 95°C): Water just below boiling, where bubbles form but don’t vigorously rise to the surface. Common for cooking delicate items.
- Poaching (about 70°C – 80°C): Water that is hot but not boiling, used for cooking eggs or fish.
3. Industrial and Practical Uses
In industrial settings or machinery, hot water can be defined differently based on its purpose.
- Hot water for washing: For commercial dishwashing or laundry, hot water might be at 55°C – 65°C to ensure sanitation without damaging the fabric or material.
- Industrial processes: Some industries use water at temperatures as high as 150°C or more under pressure for steam-based processes, though this is typically in the form of steam, not liquid water.
Summary of “Hot” Water Temperatures
- Warm water: 30°C – 37°C (comfortable for humans, typically for bathing or washing hands)
- Hot water: 40°C – 49°C (can be uncomfortable, potentially dangerous with prolonged exposure)
- Very hot water: 50°C and above (high risk of burns)
- Boiling water: 100°C (for cooking, sterilizing, and other high-temperature applications)
So, generally speaking, 40°C and above is considered hot for human use, while 100°C is hot in cooking, and any temperature over 50°C is considered risky or dangerous for direct contact.