Commonly, I/O Wait is an issue that requires the use of both advanced and basic tools such as top to be investigated. I/O Wait is difficult to troubleshoot because, by default, these tools to tell you that your system is I/O bound. However, not as many that can narrow the problem to a specific process or processes. I/O Wait is generally tied to the hard drive and the speed at which the hard drive can run compared to how much data is accessed.
A command such as "top" will go through and show the I/O Wait in many cases. The higher number, the more CPU resources are waiting for I/O access to the drive.
Generally, I/O Wait doesn't have an official number of when it is considered high. What would be regarded as high is when I/O wait affects the server's overall performance. However, anything over 50% or higher should be investigated to ensure no issues are happening onto your server.
For more information on how to check for I/O Wait, you can refer to the following article:
How to diagnose high I/O and high load with iotop