Is the iPhone X waterproof?

Water-resistant, NOT waterproof.

DylanSuggs wrote:

Is the iPhone X water proof?

No, according to: About splash, water, and dust resistance of iPhone 7 and later - Apple Support

Your iPhone is splash, water, and dust resistant and was tested under controlled laboratory conditions with a rating of IP67 under IEC standard 60529. Splash, water, and dust resistance are not permanent conditions, and resistance might decrease as a result of normal wear. Liquid damage is not covered under warranty.

To prevent liquid damage, avoid these:

• Swimming or bathing with your iPhone
• Exposing your iPhone to pressurized water or high velocity water, such as when showering, water skiing, wake boarding, surfing, jet skiing, and so on
• Using your iPhone in a sauna or steam room
• Intentionally submerging your iPhone in water
• Operating your iPhone outside the suggested temperature ranges or in extremely humid conditions
• Dropping your iPhone or subjecting it to other impacts
• Disassembling your iPhone, including removing screws

Minimize exposing your iPhone to soap, detergent, acids or acidic foods, and any liquids—for example, salt water, soapy water, pool water, perfume, insect repellent, lotions, sunscreen, oil, adhesive remover, hair dye, and solvents. If your iPhone comes into contact with any of these substances, follow the instructions to clean your iPhone.