No it doesn't leak, it's got a swimmer to stop the water from overflowing.
I read they found the H5N8 in a single wild goose in the Spree-Neisse area close to the border with Poland. and are taking precautions to stop it spreading. Brandenburg have already reacted and have intensified the monitoring of wild birds with the focus on birds which live near water. Poultry farmers have been warned to follow bio-security measures to protect their flocks.
Lets hope all that works and it doesn't spread. Slovakia, Poland, Hungary and the Czech Republic have had outbreaks since the end of last year.