Progress
Fair progress but acceleration needed
Fair progress but acceleration needed

Desired direction: Increase

Sub-categories

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Headline data

Proportion of wastewater flows connected to a collection system and adequately treated
Year Value Units Series
2014 100.0 % Proportion of domestic wastewater streams connected to a collection system
2018 100.0 % Proportion of domestic wastewater streams connected to a collection system
2018 80.0 % Proportion of domestic wastewater streams treated in a controlled manner Adequate
2012 100.0 % Proportion of domestic wastewater streams connected to a collection system
2020 100.0 % Proportion of domestic wastewater streams connected to a collection system
2012 74.0 % Proportion of domestic wastewater streams treated in a controlled manner Adequate
2016 100.0 % Proportion of domestic wastewater streams connected to a collection system
2016 76.3 % Proportion of domestic wastewater streams treated in a controlled manner Adequate
2022 79.4 % Proportion of domestic wastewater streams treated in a controlled manner Adequate
2020 80.8 % Proportion of domestic wastewater streams treated in a controlled manner Adequate
2014 77.5 % Proportion of domestic wastewater streams treated in a controlled manner Adequate
2022 99.9 % Proportion of domestic wastewater streams connected to a collection system

Geographical Area:

Unit of Measurement:

Footnote:

Methodological sheet of the indicator available for the Autonomous Community of the Basque Country.

Available indicator

Proportion of wastewater flows connected to a collection system and adequately treated
Target

6.3 By 2030, improve water quality by reducing pollution, eliminating dumping and minimizing release of hazardous chemicals and materials, halving the proportion of untreated wastewater and substantially increasing recycling and safe reuse globally
Goal

6- Ensure availability and sustainable management of water and sanitation for all
Definition

The indicator is made up of 2 series:

  • Proportion of safely treated domestic wastewater flows: Proportion of the pollution load corresponding to urban agglomerations with more than 2,000 population equivalents that treat their wastewater, reducing their pollution level to an acceptable limit for the receiving waters

  • Proportion of domestic wastewater flows connected to a collection system: Proportion of the pollution load corresponding to urban agglomerations with more than 2,000 population equivalents connected to a conduit system that collects and conveys their wastewater to a treatment facility or final discharge point
Theoretical formula

Proportion of safely treated domestic wastewater flows

\[PCC_{\text{purification}}^{t} = \left( \frac{CC_{\text{purification}}^{t}}{CC^{t}} \cdot 100 \right)\]

where:

$CC_{\text{purification}}^{t} =$ pollution load corresponding to urban agglomerations with more than 2,000 population equivalents that adequately treat their wastewater in year $t$

$CC^{t} =$ pollution load corresponding to urban agglomerations with more than 2,000 population equivalents in year $t$


Proportion of domestic wastewater flows connected to a collection system

\[PCC_{\text{collectors}}^{t} = \left( \frac{CC_{\text{collectors}}^{t}}{CC^{t}} \cdot 100 \right)\]

where:

$CC_{\text{collectors}}^{t} =$ pollution load corresponding to urban agglomerations with more than 2,000 population equivalents connected to a conduit system that collects and conveys their wastewater to a treatment facility or final discharge point $t$

$CC^{t} =$ pollution load corresponding to urban agglomerations with more than 2,000 population equivalents in year $t$
Frequency

Annual
Observations

The pollution load of an urban agglomeration is measured in equivalent inhabitants, with an equivalent inhabitant defined as the biodegradable organic load with a five-day biochemical oxygen demand of 60 grams of oxygen per day. An equivalent inhabitant represents the biodegradable organic load generated by one person in one day in a typical home.

It should be noted that the pollution load of an urban agglomeration not only includes pollution due to human excrement, but also pollution from premises used for commercial
or industrial activities, provided that it is biodegradable organic. Therefore, the number of equivalent inhabitants of an urban agglomeration is always greater than its actual number of inhabitants.

This indicator only takes into account urban agglomerations with more than 2,000 population equivalents, in accordance with Articles 3 and 4 of Directive 91/271/EEC on urban wastewater treatment.
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Indicator calculated using a methodology harmonised across the central statistical bodies of the autonomous communities
Data last updated 2025/04/22
Metadata last updated 2025/06/18

Source 1

Ministry for Ecological Transition and the Demographic Challenge
Organisation Ministry for Ecological Transition and the Demographic Challenge
Periodicity Annual
Link to data source Urban Wastewater Treatment

This section provides more information about the United Nations indicator or the European Union Sustainable Development Indicator, such as its rationale, international results, metadata, and other relevant statistics.

Rationale

Wastewater data are crucial to promote strategies for sustainable and safe wastewater use or reuse to the benefit of the world’s population health and the global environment, but also to respond to growing water demands, increasing water pollution loads, and climate change impacts on water resources.

Sustainable Development Goal 6 (SDG 6) is about ensuring the availability and sustainability of water and sanitation for all by 2030. SDG Target 6.3 sets out to improve ambient water quality, which is essential to protecting both ecosystem and human health, by eliminating, minimizing and significantly reducing different streams of pollution into water bodies.

The purpose of monitoring progress using SDG indicator 6.3.1 is to provide necessary and timely information to decision makers and stakeholders to make informed decisions to accelerate progress towards reducing water pollution, minimizing release of hazardous chemicals and increasing wastewater treatment and reuse.

The target wording covers wastewater recycling and safe reuse with implication on water use efficiency, although it is not fully addressed by the global indicator and methodology. SDG indicator 6.3.1 tracks the proportion of wastewater flows from households, services and industrial economic activities that are safely treated at the source or through centralized wastewater treatment plants before being discharged into the environment, out of the total volume of wastewater generated.

Source: United Nations Statistics Division
Comparability between the available indicator and the UN indicator

The available indicator does not comply with United Nations metadata but provides similar information.
Link to UN metadata

Metadata 6-3-1.pdf
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