Non-treated
waste water
UP-3
Urban
Environmental Problems
Pressure
1 Indicator
definition and unit of measurement
The
% of total waste water non submitted to treatment which is discharged to urban
surface water.
2 Placement
in the framework
5EAP:
Chapter
5: The themes and targets of the programme, section 5.4: Management of water
resources, establishes the framework for the management of water resources.
Community policies must aim, inter alia, at the prevention of pollution of
fresh and marine surface waters and ground water, with particular emphasis on
prevention at source.
Agenda
21:
Chapter
18: Protection of the quality and supply of freshwater resources: application
of integrated approaches to the development, management and use of water
resources, section C: Protection of water resources, water quality and aquatic
ecosystems, identifies activities to promote water pollution prevention and
control and the adequate treatment of urban waste waters.
International
conventions and agreements:
None.
Ranking:
Core
ranking:
3
(55%)
Policy
Relevance:
3
(3.2)
Analytical
Soundness:
5
(2.9)
Responsiveness:
1
(3.1)
Most
appropriate related state indicator:
Contamination
of surface water.
3 Significance
Purpose:
Waste
water is an important source of emissions to water bodies. In urban areas
non-treated waste water can cause increasing bacterial concentration, oxygen
deficiency, increased concentration of nutrients, heavy metals, and
polyaromatic hydrocarbons (PAHs). In urban areas severe contamination can occur
due to the combination of sewer overflows or by direct rain runoff through
separate sewer systems. The purpose of this indicator is to monitor trends in
the pressure from urban waste water on surface water.
Relevance:
The
discharge of non-treated urban waste water is a major cause of pollution of
surface water and eutrophication problems.
Linkages
to other pressure indicators:
The
% of non-treated waste water is linked to other indicators of pressure such as
WP-4:
Total water treated/water collected.
Targets:
None.
4 Methodological
description and underlying definitions
Underlying
definitions and concepts:
The
% of non-treated waste water discharged to surface water is linked to
inadequate water management and treatment infrastructure in cities. In several
cities a large proportion of the population is still not served by primary or
secondary sewage treatment. In addition the most advanced form of treatment -
tertiary treatment - is available only for a small percentage of the population.
Measurement
methods:
Data
on urban waste water is collect at the local scale. OECD/Eurostat collect
information on the population connected to sewerage and served by waste water
treatment plants at the national scale.
Limitations
of the indicator:
Major
problems are due to the lack of data in many cities and the quality of
available data.
Alternative
definitions:
A
possible alternative is the number of people served by treatment plants by type
of treatment.
