Source of the most amount of waste water is public sewerage systems. During the last years, the decreasing of amount and pollution of waste water was reached. In 1997, amount of discharged water into water courses dropped from 1 139 980 thousand m³ per year (in 1996) to 1 108 538 thousand m³ per year and from it treated waste water was 72.13%. This decreasing was caused by the reduction of industrial production.

Contamination of waste water discharged into watercourses
 

	Volume (thous m3 per year)	IS (tonnes per year-)	BOD5 (tonnes per year)	CODCr (tonnes per year)	ENP (tonnes per year)
1995	1 167 924	45 044	32 227	87 894	879
1996	1 139 980	41 107	27 370	75 843	627
1997	1 108 538	37 006	22 601	68 871	565

 Source: SHMÚ
 

Waste water discharged into watercourses (in thousand m³)

Source: SHMÚ