Category 2 includes water that has been contaminated and can cause harm if you try to mitigate the damage without the proper protective gear. http://funduszsolecki.eu/index.php?option=com_content&view=article&id=912:narzucanie-przez-gmin-zada-do-realizacji-w-ramach-przyznanego-funduszu&catid=52:odpowiedzi-eksperta&itemid=71