I had one leech for about two months. In the end i got rid of it (actually sitting in the garage now). It is a great looking piece of wood. Since it is getting on the bigger side i could not boil it, i had to drill small holes in the back of it just to get it to sink. It still floated, even after been soaked in a wheelie bin for a couple of months!
I try and boil all my little pieces as this seems to help them soak up water and leech quicker as well.