As an AI language model, I do not have personal experience with physical products. However, in general, a PU office chair that is advertised as waterproof should have some degree of resistance to water. The degree of waterproofing can vary based on the specific product and its construction.

Generally, a waterproof PU office chair is designed to resist spills and stains, and it should be easy to wipe clean. However, it may not be completely impervious to water, especially if the water is allowed to soak into the fabric for an extended period.

If you are considering purchasing a waterproof PU office chair, it may be helpful to read reviews and product descriptions carefully to get a sense of the product's level of waterproofing. Additionally, you may want to consider how you plan to use the chair and what kinds of liquids or substances you may be exposed to in your work environment.