Wastewater - Turning Problem to Solution

Box 4: Wastewater data and statistics

While this report considers wastewater in its broadest sense, there are considerable difficulties in assessing wastewater production, treatment, collection and reuse due to data gaps, and inconsistencies in reporting of the source of wastewater data, its scale and frequency, although there are several attempts (Qadir et al. 2020; Jones et al. 2021; UN-Habitat and WHO 2021). Another challenge is that different studies include multiple data sets and different terminology. • Qadir et al. 2020 – assessed municipal wastewater, considering it as a possible combination of (a) domestic effluent consisting of black water from toilets, grey water from kitchen, bathing and other household uses; (b) waste streams from commercial establishments and institutions; (c) industrial effluent where it is discharged into the municipal sewerage systems; and (d) stormwater and other urban run-off ending up in municipal sewerage systems. • Jones et al. 2021– used data on domestic and manufacturing wastewater, and thus excluded agricultural run-off. • UN-Habitat and WHO 2021 – the report refers explicitly to household wastewater, although in principle,

domestic wastewater includes wastewater from services and households, but flows from services are not sufficiently reported to be included at this time. Agricultural wastewater data Agricultural run-off is rarely collected and treated. Despite being a major source of pollution, country level data for agricultural run-off is not readily available, and so no estimates can be included in this report. Industrial wastewater data Only 14 countries reported on the generation and treatment of industrial wastewater in the latest assessment of SDG indicator 6.3.1, with a third of the reported wastewater volume being treated (UN-Habitat and WHO 2021). The 2021 assessment of this indicator concluded that it was not yet possible to assess regional and global estimates of the proportion of total industrial wastewater flows safely treated. Wastewater from rural areas This is another data gap due to the challenges of monitoring wastewater flows in rural areas that are not connected to sewer systems.

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