How can I know if the bathroom is waterproof? How can I know if the property is doing well? Can I check whether the bathroom is waterproof?

Generally, bathrooms should be waterproof, but the quality is different. This waterproof layer is laid under the floor tile, and it can't be detected unless the floor tile is smashed. If the water upstairs leaks into your house, it may be that the waterproofing is not done well, or that the water-using equipment, such as floor drain, is not installed properly, and it leaks downstairs as soon as you take a shower. In this case, the problem can be solved by replacing the floor drain and waterproofing the periphery of the floor drain. So we must first confirm where the water leaks.