It is infamously known as the dirtiest Czech river, even though water quality has improved significantly in the 21st century.

[2] The longest tributaries of the Bílina are:[3] The river flows through the densely populated area of the Most Basin.

The river flows through the municipal territories of Blatno, Boleboř, Jirkov, Vrskmaň, Horní Jiřetín, Litvínov, Most, Obrnice, Želenice, Bílina, Světec, Hostomice, Ohníč, Bžany, Bystřany, Rtyně nad Bílinou, Řehlovice, Trmice and Ústí nad Labem.

Paradoxically, in the upper course of the river, before it reaches the populated area, the water quality is at such a high level that it is suitable even for infants.

[4] Although it has been considered the dirtiest Czech river for decades, the state of pollution improved significantly in the 2010s.

The plan is to construct meanders and pools, extend the flow path and reduce the slope of the bottom.

[8] The improvement of water purity led to the return of fish, and already in 2006 most of the species typical of Czech rivers were found in it, e.g. Eurasian carp, perch and common bream.