Watery Cm?

Sorry for tmi but i've got reallyyy watery cm like it's just coming out like pure water. Completely clear. 
I ovulated according to my opk 10 days ago and I'm currently on cd22 periods due on Wednesday the 6th? Any reason I could be getting heavy watery cm? Or is it normal to get that when about to come on? I've never noticed it before. 
 Thanks in advance