I came across this publication today and remembered Arno's question on the forum from a year ago where he had said:

Lack of knowledge about wastewater. And where did the quotation come from that 90% of the world’s wastewater goes untreated?

This is the publication I mean:

WWAP (United Nations World Water Assessment Programme). 2017. The United Nations World Water Development
Report 2017. Wastewater: The Untapped Resource. Paris, UNESCO.
unesdoc.unesco.org/images/0024/002471/24...&utm_campaign=buffer

I was positively impressed by this report. And I really like that it's under an open access licence (CC-BY SA) which means we can easily use its content elsewhere, e.g. to beef up Wikipedia articles.

In the executive summary on Page 2 it says:

Wastewater: Global trends

On average, high-income countries treat about
70% of the municipal and industrial wastewater
they generate. That ratio drops to 38% in
upper middle-income countries and to 28% in
lower middle-income countries. In low-income
countries, only 8% undergoes treatment of any
kind. These estimates support the often-cited
approximation that, globally, over 80% of all
wastewater is discharged without treatment.

That seems quite reasonably. Probably somewhere in the body of the report it provides the sources for these figures.

Has anyone else read this report, or parts of it, and wants to share here what they find good about it?

I also like this schematic:

Hi Amo,

It’s impossible to measure the amount of untreated wastewater due to many sources that it comes from. From industrial waste to human excreta, rainfall runoff from roads, storm drains, domestic washing water, etc etc

Again as far back as 2009, the UN University was quoted as having reported that “out of 181 countries studied only 55 have information on three key aspects of wastewater: generation, treatment, and reuse. Another 69 countries have data on one or two aspects, 57 countries show no information on any aspect”

It’s also not possible to track amount of wastewater in agricultural reuse due to the rising trend in many countries.

The bottomline is that the world lacks data on wastewater for complete and reliable facts and figures.

Regards / Mwaniki

I think the UN needs to take this critique seriously and become the quality authority the taxpayers of the world think they are paying for. I would like to see a longer list of the superlatives that UN agencies are including in their reports and webpages along with the original research that went into it. This is a call for greater rigor and accountability.

National donor agencies very often fund UN agencies with core funds without requiring rigorous proposals nor do they request accountability reports as to how the funds have been used. This will unfortunately breed this sort of sloppy research and reporting that may misrepresent sincere efforts being made around the world by local stakeholders.

The 90% untreated wastewater superlative is probably just the top of the iceberg.

Hi Arno,

Thanks for pointing this out! I must admit that I've also quoted this statement in the past (I mean this one: "Right now more than 90% of the world's wastewater is discharged untreated into oceans, rivers or wherever else it can go") - I will now think twice before quoting it!

You find the statement also here in the Wikipedia article on sewage, together with the source as that UN report that you also mentioned:

en.wikipedia.org/wiki/Sewage

Proper collection and safe, nuisance-free disposal of the liquid wastes of a community are legally recognized as a necessity in an urbanized, industrialized society.[1] The reality is, however, that most wastewater produced globally remains untreated causing widespread water pollution, especially in low-income countries: A global estimate by UNDP and UN-Habitat is that 90% of all wastewater generated is released into the environment untreated.[2] In many developing countries the bulk of domestic and industrial wastewater is discharged without any treatment or after primary treatment only.

Should we change this statement on Wikipedia?

Making such a global estimate must be very difficult anyhow...

By the way, I once tried to find the original source for this often quoted figure:

50% of hospital beds in developing countries are taken up by patients suffering from water-borne diseases due to lack of WASH.

There is no original source for this either, everyone just copied from everyone else, so please don't use it! Speaking to doctors about this figure, they also told me that it would be impossible to estimate this figure and that it's highly unlikely to be anywhere near that.

So just a word of caution about these "popular figures".

Regards,
Elisabeth

It’s been in speeches given by the chair of UNSGAB in 2012. “Right now more than 90% of the world's wastewater is discharged untreated into oceans, rivers or wherever else it can go”
. www.royal-house.nl/documents/speeches/20...th-world-water-forum

Quoted by the heads of UNEP and UNHabitat in the 2010 publication “SickWater” “An estimated 90 per cent of all wastewater in developing countries is discharged untreated directly into rivers, lakes or the oceans.” www.unep.org/pdf/SickWater_screen.pdf (Corcoran et al 2010).

Quoted in UN Water reports:
“An estimated 90 per cent of all wastewater in developing countries is discharged untreated directly into rivers, lakes or the oceans” (UN Water, 2008).

And UNESCO has quoted other similar data:
“It is estimated that 70% of industrial discharges in developing countries is dumped untreated”(UNESCO, 2009).

After several hours of searching for the published source I came to a dead end. The earliest source of this quote is an unreferenced 2-page factsheet written for the UN Int’l Year of Freshwater from 2003 containing a bullet point as follows:
About 90 per cent of sewage and 70 per cent of industrial wastes in developing countries are discharged without treatment, often polluting the usable water supply. From www.un.org/events/water/factsheet.pdf

The point to make here is that the knowledge base for this sector especially when it comes to data on wastewater treatment is far from well established. And much greater efforts are required to provide a clearer view of what the status is of wastewater treatment all around the world. Take a look at the UN database Aquastat dealing with municipal wastewater (and operated by FAO with input from CGIAR-IWMI because reuse of wastewater is so widespread in the world) www.fao.org/nr/water/aquastat/wastewater/index.stm www.iwmi.cgiar.org/2014/06/global-wastewater-database/

Global water quality monitoring is not the answer (especially now that UN GEMS/Water was dismantled in 2014). Sanitation may no longer be a top priority for the UN Secretary General since UNSGAB was terminated in 2015 gwopa.org/en/gwopa-news/unsgab-journey
The sector has benefitted from several studies initiated by UNEP www.unep.org/gpa/gwi/ but more is necessary.

There’s a major challenge lurking behind the messages from the UN. On the one hand there are statements that most of the developing world’s wastewater goes untreated (whatever that actually means in technical terms). And on the other hand there is a rudimentary database set up by FAO because of the growing need to reuse wastewater to irrigate crops for urban consumption. And as the world goes more and more urban (60% by 2030) this question will become more and more apparent. How then to narrow this gap and make wastewater reuse safer? Sustainable wastewater practices will become a central focus for many decades to come.


www.emag.suez-environnement.com/en/waste...ims-challenges-11037