Originally Posted by
El Cid
The bottom of the overshoe doesn't seal onto the sole of the shoe, allowing water to get in from road spray.
Take out your insole. Take a strip of duct tape. Job done. Keeps most water out for me (I use SPD with MTB shoes). Easy to access the plate if needed.
I wonder is some shoe goo or clear RTV silicone will work on the inside as well.
Edit: I will stick by my suggestion, but [MENTION=21724]cyccommute[/MENTION] has a better one with the furnace tape. Also larger shoe is kep along with larger over socks for layers, otherwise it will get too tight and reduce circulation and make you feet cold as a result.