If you are using the system correctly this is impossible. However, if the extract chamber overflows after flipping there can only be one reason for it. You didn't add enough ground coffee to the filter! We’ve tested the BOD® thousands of times and built every component to be the exact perfect size, making it impossible for overflowing to occur.
Keep in mind that you must use approximately 8 oz. of coffee by weight NOT by volume for each brew cycle. If you were to use 8 oz. of coffee by volume, (using a measuring cup and not weighing it out), you won’t even fill up half of the filter which means the water added to coffee is not in the proper ratio and in turn will cause overflowing.
Just make sure that you fill the filter almost full, or about ½ inch to ¾ of an inch below the top. When you do that, it’s impossible for overflowing to occur.