In 2024 only about 56% of the wastewater produced by households worldwide was safely treated, and in 2023 only 56% of the rivers, lakes and aquifers that countries monitor had good water quality, with little sign of improvement since monitoring began.
Updated October 15, 2026. Written from the sources listed below, not independently peer-reviewed.
In low-income countries, roughly what share of household wastewater is safely treated before it is released into rivers, lakes or the ground?
56%
Household wastewater safely treated
185 of 332 billion cubic metres generated in 2024. Largely unchanged since the first estimates were published in 2020; based on 142 countries and territories covering 88% of household wastewater flows.
Data year 2024. Source: United Nations Statistics Division, 2026
56%
Monitored water bodies with good quality
Rivers, lakes and groundwater bodies assessed in 120 countries. Country reporting rose from 39 in 2017, but many water bodies are never monitored.
Data year 2023. Source: UN-Water, 2026
Under 3%
Water quality measurements from the poorer half of countries
About 60,000 of the more than 2 million measurements used for the 2023 global assessment came from the lower-income half of reporting countries.
Data year 2023. Source: UNEP on behalf of UN-Water, 2024
Global estimates for SDG indicator 6.3.1 as published in the UN SDG Global Database; only these three years have been estimated. Each estimate rests on the countries with recent national data at the time, which changed between rounds (for example, Brazil and Pakistan dropped out in 2024 because their data had become too old), so small ups and downs should not be read as real change; the UN describes the share as largely unchanged since 2020.
SDG target 6.3 calls for better water quality by 2030 through less pollution and dumping, fewer hazardous chemicals, half as much untreated wastewater and much more safe recycling and reuse. The share of household wastewater safely treated has stayed at about 56% since the first estimates in 2020, and where long-term water quality records exist, mostly in high-income countries, they show little change or a slow deterioration since 2017. Trends in low- and middle-income countries cannot be judged because monitoring is sparse and irregular.
Low-income countries safely treat about 26% of their household wastewater, compared with more than 90% in high-income countries. In Oceania and sub-Saharan Africa the share is only around 15–20%.
Source: UN-Water, 2026In 2024, 19% of household wastewater was safely treated in sub-Saharan Africa, 20% in the least developed countries and 28% in Central and Southern Asia, against 87% in Europe and Northern America.
Source: United Nations Statistics Division, 2026Rivers are in worse shape than groundwater among the water bodies that are monitored: in 2023, 50% of assessed rivers had good quality, compared with 79% of assessed groundwater bodies.
Source: United Nations Statistics Division, 2026Lakes and groundwater in poorer countries are barely monitored. In 2023, the lower-income half of countries reported on fewer than 300 of nearly 14,000 assessed lakes and fewer than 1,000 of 13,500 groundwater bodies.
Source: UNEP on behalf of UN-Water, 2024Instead of one “percent solved” score, DO GOOD rates three separate dimensions. A problem can have mature solutions that still reach too few people. These ratings are an editorial reading of the sources on this page, not a measured index.
Has the situation improved in the real world?
LowThe global share of household wastewater safely treated has been stuck at about 56% since 2020, and in the countries with long-term records water quality shows minimal change or gradual deterioration since 2017.
How mature and validated are the available solutions?
ModerateSewers connected to treatment plants are proven, and wastewater collected in sewers is mostly treated safely (81% in 2024). Controlling pollution that does not pass through a pipe, such as fertiliser runoff from farms, and managing septic tanks safely are much less well solved.
How widely are effective solutions actually used?
ModerateMore than 90% of household wastewater is safely treated in high-income countries, but only 26% in low-income countries and 15–20% in Oceania and sub-Saharan Africa.
Nearly 100 countries and territories lack enough data for a national wastewater estimate, data for some large countries such as Brazil and Pakistan had become too old to use in 2024, and water quality trends in low- and middle-income countries remain highly uncertain because monitoring is sparse and irregular.
The UN's 2026 review of SDG 6 found no change at global level in either wastewater treatment or ambient water quality, with stagnation in the least developed, landlocked and small island developing countries. Monitoring is the one area that is clearly growing.
Rivers, lakes and groundwater are polluted mainly by two things: wastewater from homes, businesses and industry, and runoff from farms. In 2024 households generated an estimated 332 billion cubic metres of wastewater, of which only 185 billion cubic metres were safely treated. About 17% was never collected at all, and wastewater held in septic tanks was often not emptied and treated properly. Along with untreated sewage come excess nutrients (nitrogen and phosphorus), sediment, pathogens, pesticides, pharmaceuticals, heavy metals and microplastics. Nutrient pollution from farming and wastewater roughly doubled over the last century and, according to modelling studies cited by UNEP, is expected to double again by 2050.
Polluted water harms people who drink it, wash in it, fish in it or eat crops irrigated with it. A study cited by UNEP estimated that water pollution caused 1.4 million premature deaths in 2019, and 122 million people still drank untreated water from rivers, lakes and other surface sources in 2022. WHO estimates that at least 10% of the world's population eats food irrigated with wastewater. The gap is widest where incomes are lowest: low-income countries safely treat about a quarter of their household wastewater, and the poorer half of the world's countries produce only a tiny share of the water quality measurements needed to know how polluted their rivers and lakes are.
SDG target 6.3 is tracked with two indicators: one looks at the wastewater released into the environment (6.3.1), the other at the state of the receiving rivers, lakes and aquifers (6.3.2).
Safely treated household wastewater
Wastewater from households (and, in principle, services) counts as safely treated when it is collected in a sewer or a septic tank and treated in line with national or local standards, which for the global estimate means at least secondary treatment. Wastewater that is not collected, or collected but not treated to that level, counts as not safely treated.
Industrial wastewater
The same indicator has an industrial component, but in 2023 only 17 countries, home to about 5% of the world's population, reported how much of their industrial wastewater was safely treated, so no global estimate exists.
Good ambient water quality
A river, lake or groundwater body counts as having good quality when at least 80% of its monitoring results meet national targets. The global indicator uses five core measurements that reflect nutrient enrichment, oxygen depletion, salinity and acidity: dissolved oxygen, salinity, nitrogen, phosphorus and pH.
What the core indicator misses
Pesticides, pharmaceuticals, heavy metals, microplastics and many other pollutants are not part of the five core measurements. Countries can add them in an optional second level of reporting, which can also use Earth observation and citizen science data.
What works
Collecting wastewater in sewers and treating it at central plants is the most reliable route: in 2024, 55% of household wastewater went into sewers, 92% of that reached a treatment plant, and 81% was safely treated.
Limits
Sewers and plants are costly to build and run and must be maintained for decades. In 2022, households without adequate sewer or septic connections accounted for 45% of the household wastewater that was not safely treated.
What works
Where sewers are impractical, septic tanks can serve households if the sludge is regularly emptied, transported and treated. About 27% of household wastewater went into septic tanks in 2024.
Limits
The chain usually breaks after the tank: only about half of septic tank wastewater was delivered to treatment, and 46% was safely treated, so badly built or managed systems leak into drains and groundwater.
What works
Discharge permits with treatment standards, and public reporting of what is released, make industrial pollution visible and enforceable. The number of countries reporting safely treated industrial wastewater rose from 3 in 2015 to 17 in 2023.
Limits
Those 17 countries cover about 5% of the world's population. Confidentiality agreements, factories that draw their own water outside public statistics, and responsibility split across ministries, regulators and utilities keep most industrial flows unmeasured.
What works
Regular sampling against national targets shows where water is degraded and whether action is working. The number of countries reporting on ambient water quality rose from 39 in 2017 to 120 in 2023.
Limits
Monitoring is concentrated in high-income countries and in rivers; many low-income countries cannot run programmes that track trends reliably, and lakes and groundwater are monitored much less.
What works
Treated wastewater can be reused for irrigation, industry or drinking supplies, which relieves pressure on rivers and aquifers. Singapore's reduction in water stress came partly from diversifying supply through desalination and water reuse.
Limits
Reuse can also be unsafe: WHO estimates that at least 10% of the world's population eats food irrigated with wastewater, and much reuse lacks adequate treatment, controls on use or regulatory oversight.
Promising, but not proven at scale. The stage shows how far each approach has come; it is not a recommendation.
In the 2023 reporting round, Sierra Leone and Zambia became the first countries to combine water quality data collected by volunteers with national regulatory data for SDG reporting. In Sierra Leone this doubled the number of water bodies assessed, and five more countries were expected to follow in 2026.
Earth observation and computer models are accepted as data sources in the optional second level of SDG 6.3.2 reporting and could cover lakes and remote rivers that are never sampled. How accurately they can stand in for on-the-ground sampling of the core measurements has yet to be shown at scale.
Treatment plants and sludge can supply irrigation water, fertiliser and energy, turning a cost into a resource. The UN's 2026 review points to these opportunities, but WHO warns that reuse is often done without adequate treatment or regulation, so products must be proven safe before wider use.
Implementation gap
About 17% of household wastewater was not collected at all in 2024, by either a sewer or a septic tank, so it reached drains, soil and water bodies with no treatment.
Implementation gap
Septic tanks received about 27% of household wastewater in 2024, but only about half of it reached treatment and 46% was safely treated.
Coordination gap
Confidentiality agreements, self-supplied industrial water and fragmented responsibilities among ministries, regulators and utilities mean that a global estimate of industrial wastewater treatment is not possible.
Technology gap
Agriculture is one of the two main stressors on freshwater quality. Nitrogen and phosphorus pollution from farming and wastewater roughly doubled over the last century and is projected to double again by 2050, and fertiliser runoff cannot be piped to a treatment plant.
Knowledge gap
The lower-income half of countries supplied under 3% of the more than 2 million measurements used in 2023, so where data are limited it is simply unknown whether water is clean. High scores from sparse data in some low-income countries may not reflect real conditions.
Implementation gap
Seventy per cent of countries report insufficient funding for integrated water resources management, and the UN calls for revenue-raising and cost-recovery arrangements to pay for services such as wastewater treatment.
Unresolved questions, not vetted breakthroughs. Answering any of them would change what is possible.
Can satellite data, models and citizen science reliably estimate water quality in the many countries and water bodies with no regular sampling, and how should their uncertainty be reported?
How much harm do pharmaceuticals, pesticides, heavy metals and microplastics cause to health and ecosystems at the concentrations found in rivers and groundwater, and which of them should be monitored first where budgets are small?
For rapidly growing towns in low-income countries, what combination of sewers, septic systems with managed emptying and smaller local treatment plants cleans up rivers fastest for the money?
Which combinations of regulation, incentives and farming practices reduce nitrogen and phosphorus losses at scale while keeping yields and farm incomes stable?
Return unused medicines to a pharmacy or collection point, and put oils, paints, solvents and wet wipes in the bin or hazardous waste collection rather than the sink, toilet or storm drain.
Many rivers and lakes have volunteer monitoring groups that sample water and share the results with authorities. Joining one adds data where official monitoring is thin.
Apply only what plants need and avoid spreading them before rain, so less washes into nearby streams and groundwater.
Utilities and environmental agencies often publish treatment and water quality reports. Read them, and ask your local representatives whether sewage overflows and septic systems in your area are monitored and fixed.
Ideas visitors sent in for this challenge, read by the DO GOOD team and pinned with permission. The colour shows the kind of contribution.
Loading the board…
What happens next
The DO GOOD team reads every idea and sorts it by colour: solution, research question, existing project, evidence or local action.
If you agree to publication, it can be pinned to this board. Contact details are never shown.
Pinned ideas are not reviewed by scientists and are not endorsed by DO GOOD.
This page is a research overview. DO GOOD does not run a dedicated programme on this challenge, and donations are not earmarked for it. You can join our volunteer work and outreach.
United Nations Statistics Division, published 2026
Official UN summary of SDG 6.3: 56% of household wastewater safely treated in 2024 (185 of 332 billion cubic metres), breakdowns for sewers, septic tanks and uncollected flows, data coverage (142 countries, 88% of flows, nearly 100 countries without data) and the 6.3.2 trend (minimal change or gradual deterioration since 2017 where long-term data exist).
UN-Water, published 2026
Ten-year review of SDG 6 (June 2026): 56% of monitored water bodies in 120 countries with good quality in 2023, 26% of household wastewater safely treated in low-income countries versus over 90% in high-income countries, industrial wastewater reporting (17 countries, 5% of population), growth in reporting since 2015/2017, no change at global level, data gaps and financing.
UNEP on behalf of UN-Water, published 2024
Custodian report on SDG 6.3.2 for the 2023 data round: method (80% of values meeting targets, five core parameters), 120 reporting countries and 2.1 million measurements, the under-3% share from the lower-income half of countries, lake and groundwater gaps, main pollution pressures and nutrient trends, health figures cited from other studies, and the first use of citizen science data.
UN-Water, published 2024
Summary of the 2024 SDG 6.3.1 progress report (2022 data): definition of safely treated wastewater (at least secondary treatment or national standards), the 45% of unsafely treated household wastewater from homes without adequate collection, and limited industrial data. Its 2022 headline figures are superseded by the 2024 estimates in the UN SDG Extended Report 2026.
United Nations Statistics Division (data from WHO, UN-Habitat and UNEP), published 2026
Official global and regional time series: world share of household wastewater safely treated in 2020, 2022 and 2024, regional 2024 values, and the 2023 share of assessed rivers and groundwater bodies with good quality (same API with indicator=6.3.2).
World Health Organization, published 2024
WHO fact sheet of 22 March 2024: at least 10% of the world's population thought to eat food irrigated with wastewater, unsafe reuse without adequate treatment or oversight, leaking pits and septic tanks, and the link between poor sanitation and antimicrobial resistance. Its 2020 wastewater figure is superseded by the 2024 estimate.