Monovalve
 

While cleaning the monovalve (see 126 climate control thread) I noticed that there is a small hole drilled through the brass washer that holds the diaphram in place. It goes all the way through into area encircled by the screen. Looks like it was manufactured that way. If the diaphram's job is to keep the water out, why drill a hole to let it in? Is this normal or do I have a defective monovalve insert?