The safety of tap water is highly geographic. In 2026, roughly 74% of the global population has access to "safely managed" drinking water, but this leaves over 2 billion people without it. In high-income regions like North America, Western Europe, Japan, and Australia, tap water is generally excellent and undergoes rigorous testing. However, even in these regions, localized issues like lead pipes or chemical runoff can occur. In many parts of Africa, Southeast Asia, and Latin America, tap water is frequently contaminated with bacteria or heavy metals, making it unsafe to drink without boiling or filtration. In 2026, the UN has warned of "Global Water Bankruptcy," where pollution and over-extraction are making even historically safe sources more precarious. For travelers, the "rule of thumb" is to stick to bottled or filtered water in developing nations. Even for brushing teeth, using bottled water is a safe precaution in "high-risk" zones to avoid traveler's diarrhea or more serious waterborne illnesses.