A CRITICAL REVIEW OF GLOBAL STATISTICS
ON HOUSEHOLD FRESHWATER USE AND ACCESS
Daniel Clarke, clarke@un.org, United Nations Statistics Division, DESA
ABSTRACT
Despite significant conceptual and methodological developments in environment statistics the
availability and quality of basic environmental data is a major problem in many countries.
This paper presents a detailed analysis of household freshwater use and access data received
from official national sources for the UNSD/UNEP Questionnaire on Environment Statistics.
The paper reviews the available statistics in the context of coherence and comparability
between countries, across variables, and in relation to other major national and international
data sources.
The purpose of the study is to develop recommendations for future data collections on water
use and access based on general conclusions on the current availability and comparability of
these statistics. The current variability in definitions and approaches is illustrated and specific
challenges in producing comparable data are highlighted. The paper concludes by proposing
some potential practical steps for improving the quality of water statistics in light of the
identified challenges.
Key words: Water statistics, household water use, data quality
1. Background
The UNSD/UNEP Questionnaire on Environment Statistics is sent biennially to national
statistical offices and ministries of environment (or equivalent) in approximately 170 United
Nations member countries and territories that are not members of the Organisation of
Economic Co-operation and Development (OECD) and the European Union (EU).
Comparable statistics for OECD and EU are collected in the corresponding biennium through
the Joint OECD/Eurostat Questionnaire on the State of the Environment. Current and past
UNSD/UNEP Questionnaires are available on the UNSD website in five languages.1 The
proportion of countries that provided some data to the UNSD/UNEP Questionnaire in the
most recent (2008) round was nearly 50% (83 countries), up from around 35% in 2001.
UNSD makes a selection of data collected through the UNSD/UNEP Questionnaire available
on its website, along with corresponding statistics produced by OECD and Eurostat. Only a
limited number of water indicators are disseminated because of poor data quality (particularly
international comparability). The purpose of this study is to investigate the key quality issues
for household water use statistics and develop some recommendations for improvement.
1
http://unstats.un.org/unsd/environment/questionnaire.htm
1
2. Volume of household freshwater use
Currently the main international sources for statistics on household water use
volumes are the UNSD/UNEP Questionnaire on Environment Statistics, the Joint
OECD/Eurostat Questionnaire on the State of the Enviornment, and the FAO Aquastat main
country database. Aquastat also regularly sends a questionnaire to collect official water
statistics from countries; however, most data used in this analysis were notated as estimates or
modelled data. Freshwater use is defined in the UNSD/UNEP Questionnaire as the quantity of
freshwater actually used by end users including water delivered by the water supply industry
(ISIC 36), water directly abstracted for own use and water received from other parties. It
excludes freshwater returned without use. Household water use refers to all freshwater used in
the normal functioning of households (e.g. drinking or washing) and may include household
garden watering but not freshwater used for commercial agriculture. The definitions used in
the UNSD/UNEP Questionnaire are consistent with the International Recommendations for
Water Statistics (IRWS), which was endorsed by the United Nations Statistical Commission
at its 41st session in February, 2010.
Data on household freshwater use have been collected through the UNSD/UNEP
Questionnaire for just 35 countries and territories. However, responses have increased over
time and more data are available for more recent years than earlier periods in the time series.
Household freshwater use includes freshwater obtained from all sources; though most
reported data are equivalent to deliveries to households by the water supply industry.
Volumes of freshwater use from sources such as household own-abstractions from private
wells or nearby surface or groundwater are normally unknown unless estimated using water
use coefficients. Use coefficients are calculated based on existing household data from
surveys, censuses, or other records that can approximate average water use by resident
households that aren’t connected to the water supply industry.
In summary, only in a minority of cases do national freshwater use statistics include all
households and all sources in accordance with the definition. Data provided in the majority of
cases apparently represent the water supply industry-connected populations and volumes only.
Except in a few cases, household freshwater use not supplied by the water supply industry
represent a significant omission for non-OECD countries. Detailed guidance and international
standards for developing and implementing household water use coefficients are needed in
order to improve the availability of comparable data on household freshwater use volumes
following the definition in the UNSD/UNEP Questionnaire and the IRWS.
3. Household freshwater use volumes from FAO Aquastat and OECD/Eurostat
The term “withdrawals” is used by FAO Aquastat to produce freshwater “use” indicators in
the Aquastat main country database. According to Aquastat’s online glossary, 2 water
withdrawals are defined as: “Annual quantity of freshwater withdrawn for agricultural,
industrial and municipal purposes. It includes renewable freshwater resources as well as
potential over-abstraction of renewable groundwater or withdrawal of fossil groundwater and
eventual use of desalinated water or treated wastewater. It does not include other categories of
2
http://www.fao.org/nr/water/aquastat/data/glossary/search.html
2
water use, such as for cooling of power plants, mining, recreation, navigation,
fisheries, etc., which are sectors that are characterized by a very low net
consumption rate.”
Aquastat withdrawals are essentially equivalent to freshwater use as defined in the
UNSD/UNEP Questionnaire and IRWS but with some subtle differences. Aquastat
withdrawals apparently include losses during transport, and therefore total withdrawals are
conceptually closer to the UNSD/UNEP Questionnaire indicator: total freshwater available
for use. Aquastat withdrawals are reported for three user categories: “municipal”,
“agricultural”, and “industrial”. Municipal withdrawals are usually computed as the total
water withdrawn by the “public distribution network” (i.e. the water supply industry) for
direct use by the population and can include industries connected to the municipal network.
Aquastat also has a related indicator called domestic water withdrawals, which is sometimes
used interchangeably with municipal water withdrawal, but is meant to focus on human needs
(drinking, cooking, cleaning, and sanitation). However, domestic water withdrawal statistics
are not currently included in the Aquastat main country database.
Although the two indicators are not directly comparable, it is expected that Aquastat
municipal withdrawals volumes should generally exceed household freshwater use volumes
for respective countries and reference periods. A comparison of the two datasets shows that
this expectation is realized for most cases but with a few exceptions and there are some large
discrepancies in per capita volumes. Although the Aquastat main country database has
comparably better coverage in terms of the number of countries or territories with at least one
data point, there are large differences in the coverage of data collected from the UNSD/UNEP
Questionnaire; therefore, data availability for international analyses would be greatly
improved if a precise correspondence between these statistics could be established. The subtle
differences between the definitions of Aquastat municipal withdrawals and household
freshwater use have important implications for their interpretation; but a robust method for
users to compare this data across sources should be possible.
The Joint OECD/Eurostat Questionnaire collects household water use data by supply
categories: water supply industry and “self supply”. However, in Eurostat’s online database
only “use of water from public water supply by services and private households” is available.
The European Environment Agency (EEA) also produces an indicator using Eurostat water
statistics called “urban water use per inhabitant”. This indicator is estimated by calculating
total abstractions by the water supply industry (for all uses) by the country’s resident
population, which is usually comparable with Aquastat municipal withdrawals.
4. Freshwater quality and access
There is a relative abundance of data on types (technologies) of access to freshwater and
sanitation by households from international household surveys such as Multiple Indicator
Cluster Surveys (MICS), Demographic and Health Surveys (DHS), and in household census
questionnaires. Data from these sources are used to identify households using “improved
sources” of freshwater and sanitation in the MDG framework.
The MDG water and sanitation “improved sources” indicators were developed to allow for
international monitoring of sustainable household access to freshwater of a minimum quality
standard. Data on populations connected to the water supply industry and wastewater
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collection are used for a similar purpose, though the scopes of the two measures
are different. Physical tests of a household’s freshwater source would be a more
direct measure of water quality, but direct quality assessments that are
comparable across sources and over time are not available for a variety of reasons. As has
been argued in a paper from FAO, “differences in water quality may be significant locally but
are difficult to aggregate in a meaningful way...In addition, water quality must be expressed
not only in terms of physical, biological and chemical variables, but also according to quality
standards that vary according to use.” (FAO, 2003) However, increasing use of portable
testing kits is promising for potentially collecting water quality data through regular survey
programs, which could potentially be used to produce internationally comparable indicators.
Time series data are collected through the UNSD/UNEP Questionnaire on proportions of
population connected to the water supply industry and population connected to the wastewater
collection system. 39 and 48 non-OECD and non-EU countries have provided population
proportions for the water supply industry and wastewater collection system, respectively. For
most countries with available data in matching years, the “improved sources” proportions are
larger, which follows general expectations about the relationship between these indicators.3
But there are a number of exceptions as well as cases of divergent trends.
Most discrepancies and divergent trends are accountable by differences in the relative
importance of “improved sources” that are not part of the water supply and wastewater
collection systems (e.g. rainwater collection and use of private septic tanks). Many
households in non-OECD countries use more than one source of freshwater. Data submitted
to the UNSD/UNEP Questionnaire come from administrative records and generally will
include all household connections regardless of how they are used. Therefore, detailed
information on the actual experiences of households is lost in the summary indicators. For
example, data on reliance on bottled water, informal vendors or unprotected surface and
groundwater sources are of particular relevance. Analysis of microdata obtained from MICS
and DHS datasets can be used to investigate these details underlying the indicator trends
across countries. Therefore, it is recommended to combine national statistics on freshwater
and sanitation connections from industry administrative records with the detailed household
survey and census data in order to have a more accurate picture for policy analysis.
5. Conclusions
Analysis of household water use statistics is seriously limited by the level of quality
(particularly international and cross-source comparability) and coverage of data available
from the main international sources. Very significant improvements could be made through
greater coherence and more precisely defined relationships between national and international
databases. Cross-source and cross-indicator verifications of information would help reduce or
clarify some of the discrepancies that can harm confidence in water statistics in general. This
process would also help improve the application of available data from different sources and
methods for constructing indicators. The recent adoption by the UN Statistical Commission of
IRWS was an important step towards this goal. However, many conceptual differences remain
in the available datasets and there is a need for more detailed practical guidance.
Usually public water supply and wastewater collection connections indicate some sort of “piped” access.
Therefore, generally all such cases would be included as “improved sources” if they are the main source for the
household. One exception is freshwater deliveries by tanker truck/cart; however this population is usually a
small percentage of the total. See IRWS for more info.
3
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References
1.
2.
3.
4.
5.
6.
7.
8.
Daly, Herman E. 1992. From Empty-world Economics to Full-world Economics: Recognizing an
Historical Turning Point in Economic Development, in Population, Technology and Lifestyle: The
Transition to Sustainability. World Bank and UNESCO. Washington, D.C.
FAO. 2003. Review of World Water Resources by Country. Rome
Gleik, Peter H. 1997. Basic Water Needs. [Paper] for Pacific Institute, Oakland, CA
UN. 2006. Water: A Shared Responsibility, The United Nations World Water Development Report 2.
UNESCO and Berghahn Books, New York, NY
UNICEF. 2006. Multiple Indicator Cluster Survey Manual: Monitoring the Situation of Children and
Women. Division of Policy and Planning, New York, NY
UNSD.
2010.
International
Recommendations
for
Water
Statistics,
final
draft:
http://unstats.un.org/unsd/envaccounting/irws/
UNSD. 2006. System of Environmental-Economic Accounting for Water (SEEAW). Final draft:
http://unstats.un.org/unsd/envaccounting/seeaw.asp
WHO/UNICEF. 2006. Meeting the MDG drinking water and sanitation target: The urban and rural
challenge of the decade. New York, NY
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