Ensure availability and sustainable management of water and sanitation for all
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.
Proportion of domestic and industrial wastewater flow safely treated
- More data is required for work on SDG 6.3.1 to begin.
The United Nations Statistics Division (UNSD) collects data on the volume of wastewater treated in independent treatment facilities, in other treatment plants and in urban wastewater treatment plants (WWTPs). This is data we currently have access to. The Joint Monitoring Programme also report estimates for wastewater treatment in the UK between 2008 and 2015. Links for available datasets are listed below.
- For each Waste Water treatment plant, We need more data on how much of the wastewater entering the treatment plant is actually treated if not 100%.
- More data is required on the volume of wastewater getting at least primary treatment, secondary treatment or above.
- An additional requirement is to have the volume of waste water entering each treatment plant disaggregated by source (Industrial, Domestic, Services).
There are several water companies in England and Wales (listed below) and each of them should have this data for their respective service areas. OECD/ Eurostat collect data on volumes of industrial and urban wastewater discharges OECD/Eurostat databases therefore disaggregate the flow of discharged wastewater by type (for example, urban and industrial discharges). However, Data for the UK is not yet available.
This indicator aims to measure two things:
- The volume of wastewater generated through different activities such as domestic, services and industrial.
- It also measures the volume of wastewater which are safely treated before discharge into the environment.
Both measurements will be in units of 1000 m3/day, although some data sources may use other units that require conversion. The ratio of the volume treated to the volume generated is taken as the ‘proportion of wastewater flow safely treated’.
Wastewater flows will be classified into industrial, services, and domestic flows, with reference to the International Standard Industrial Classification of All Economic Activities Revision 4 (ISIC). To the extent possible, the proportion of each of these waste streams that is safely treated before discharge to the environment will be calculated.
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.
Total wastewater generation and treatment can be quantified at the national level, and wastewater can also be disaggregated into different types of flows, based on ISIC categories. Domestic wastewater generated by private households, as well as wastewater generated by economic activities covered by ISIC categories, may or may not be pre-treated on premises before discharge to either the sewer for further treatment or directly to the environment.
The main sources of wastewater include wastewater from households, services and industries, i.e. point sources of one or more pollutant(s) that can be geographically located and represented as a point on a map. Diffused pollution from non-point sources such as runoff from urban and agricultural land can contribute quite significantly to wastewater flows and therefore its progressive inclusion in the global monitoring framework will be important. Presently, it cannot be monitored at source and its impact on ambient water quality will be monitored under indicator 6.3.2 “Proportion of bodies of water with good ambient water quality”.
Differentiating between the different wastewater streams is important as policy decisions need to be guided by the polluter pays principle. However, wastewater conveyed by combined sewers usually combines both hazardous and non-hazardous substances discharged from different sources, but also runoff and urban stormwater, which cannot be separately tracked and monitored. As a consequence, although the flow of wastewater generated can be disaggregated by sources (domestic, services industrial), the treated wastewater statistics are most commonly disaggregated by type (e.g. urban and industrial) and/or level of treatment (e.g. secondary) rather than by sources.
Total wastewater flows can be classified into three main categories:
- Industrial (ISIC divisions 05-35)
- Services (ISIC divisions 45-96)
- Domestic (private households)
Wastewater treatment can be classified into three main categories:
- Primary
- Secondary
- Tertiary
Where possible, treatment will additionally be classified into either on-premises or off-premises treatment.
There is a relative lack of knowledge about the volumes of wastewater generated and treated, because wastewater statistics are in an early stage of development in many countries and not regularly produced or reported. Monitoring is relatively complex, costly, and data are not systematically aggregated to the national level and/or accessible; especially industrial wastewater data which are in general poorly monitored and seldom aggregated at national level. To some extent, this may be explained by the fact that a large proportion of the industrial water requirements are covered by the use of private systems using non-public/drinking water supply (groundwater, rivers and wells) which are not systematically included in the national statistics.
Diffused pollution from non-point sources such as runoff from urban and agricultural land can contribute significantly to wastewater flows, and therefore its progressive inclusion in the global monitoring framework will be important. Presently, it cannot be monitored at source and its impact on ambient water quality will be monitored indirectly under indicator 6.3.2 on the proportion of bodies of water with good ambient water quality. Different types of wastewater have different degrees of contamination and pose different levels of threat to the environment and public health. Some data exist on the pollutant loading in terms of BOD5 and COD (kg O2/day), but these are not as widely available as data on volumes and will not be used at present for indicator 6.3.1. It is anticipated that future data drives will include more information on pollutant loadings that could be eventually featured in SDG 6.3.1 reporting.
The amount of wastewater generated is calculated by summing all of the wastewater generated by different economic activities and households. Wastewater flows are expressed in units of 1000 m3 /day, although some data sources may use other units that require conversion.
The amount of wastewater safely treated is calculated by summing all of the wastewater flows which receive treatment considered equivalent to secondary treatment or better. This wastewater flow is expressed in units of 1000 m3 /day, although some data sources may use other units that require conversion.
The proportion of wastewater flows which are safely treated is calculated as a ratio of the amount of wastewater safely treated to the amount of wastewater generated
From the wastewater supplied by EA covering from 2011 - 2021, Total wastewater treated can be calculated using the 'Average Flow' column for each year. This is working with the understanding that all flow data stated is all being treated. Based on the current dataset, Yearly aggregations can be calculated for England across the 10 year period from 2011 to 2021. However, the dataset does not currently provide a further breakdown on the level of treatment which is required to complete the Habitat Table.
- Anglian Water
- Dwrcymru
- Hafren Dyfrdwy
- Northumbrian Water
- Severn Trent Water
- South West Water
- Southern Water
- Thames Water
- United Utilities
- Wessex Water
- Yorkshire Water
- Progress on Wastewater Treatment – 2021 Update
- United Nations SDG 6 Monitor and Report
- United Nation SDG 6 snapshot in United Kingdom Of Great Britain And Northern Ireland
- Defra: Waste water treatment in the United Kingdom – 2012
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government-ease-sewage-discharge-rules-amid-chemical-shortage : (07/Sep/21)
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Wastewater is 'polluting rivers with microplastic : (13/May/21)
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Sewage discharged into rivers 400,000 times in 2020 : (31/Mar/21)
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Hundreds of sewage leaks detected thanks to AI : (11/Mar/21)
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Thames-water-fined-23m-for-raw-sewage-pollution-incident : (26/Feb/21)
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raw-sewage-discharged-stream-buckinghamshire-thames-water : (01/Feb/21)
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Southern Water punished over 'shocking' wastewater spills : (25/Jun/19)
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Organisation for Economic Cooperation and Development (OECD)
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Data.gov.uk : Urban Waste Water Treatment Directive Treatment Plants
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European Commission Urban Wastewater website UK