Water statistics

Contact organisation

National Statistical Institute

Contact organisation unit

 “Environmental and Energy accounts” Department

Contact name

Stoyanka Mastikova

Contact person function

State expert

Contact mail address

2, P. Volov Str.; 1038 Sofia, Bulgaria

Contact email address

[email protected]

Contact phone number

+359 2 9857 637

Contact fax number
Metadata update
Metadata last certified20 December 2018
Metadata last posted20 December 2018
Metadata last update20 December 2018
Statistical presentation
Data description

Information on water reflects different quantitative aspects of water abstraction, water supply and water use by economy and households,  wastewater treatment and discharge into water bodies.

Information on water abstraction makes it possible to identify the main sources and to quantify the distribution of water use between different activities. 

The quantity of fresh and non-fresh water used are presented by categories of water supply and by basic economic activities - agriculture, mining and manufacturing, energy, services and households. Quantitative data are provided for public water supply about collection, treatment and water supply. 

The quantities of generated wastewater are divided by main sources of anthropogenic activity. The observation of wastewater flows is from water source to water receiver. The total quantity of wastewater discharged into water bodies is divided by place of discharge and their treatment in urban and other wastewater treatment plants, as well as independent treatment of wastewater from the population. Data on urban wastewater treatment plants (UWWTP) according to the available treatment technology - primary, secondary and tertiary are presented. 

Data about the relative share of population connected to water services, sewage and wastewater treatment as well as the share of population with irregular water supply due to water shortage are presented.

The information about available water supply and sewage network reflects the state of infrastructure and the growth rates of renovation. Detailed data about the type of pipes and years in which they have been put into exploitation is collected once at every five years.

The data are produced at administrative - territorial level and River Basin District level. The presented results on water use are calculated on the basis of reported statistical data and estimation methods.

Classification system

· National Classification of Economic Activities (NCEA-2003, for international use NACE.BG 2003);

· Classification of Economic Activities (CEA-2008, for international use NACE.BG 2008);

· Unified Classification of the Administrative-Territorial and Territorial Units in Bulgaria (UCATTU);

· List of settlements by river basins.

Sector coverage

Information is ensured by conducting the following annual statistical surveys included in the National Statistical Programme:

· Water supply, sewage and treatment - exhaustive survey. Data is collected from public water supply companies dealing with water collection, treatment, water supply and wastewater collection, discharge and treatment (water supply companies/UWWTP operators and irrigation systems).

· Water use - partial statistical survey focused on the larger water users. Criterion for coverage is the usage by enterprises of more than 36 thousand m3 of water annually for their activity. Enterprises below this criterion submit data on a voluntary basis. The survey of enterprises for hydroelectricity generation is exhaustive.

Statistical concepts and definitions

Water abstraction is divided into two categories - fresh and non-fresh water.

Fresh water: to surface water are allocated water on land (including the Danube river), and to the groundwater - all water which is below the surface of the ground in the saturation zone and in direct contact with the earth layers.

Non-fresh water: are the sea and transitional waters. Since 2006 only sea water is included to non-fresh waters as according to the Classification for characterization of surface types' water bodies under the Water Framework Directive, transitional waters are not identified in Bulgaria.

Water supply categories: Self-supply; Public water supply, Irrigation systems and other supply: (raw and reused/ wastewater received from other users).

Gross water abstraction is a sum of fresh water abstracted for distribution and self-supply of the enterprises. Water for production of hydroelectricity is a separate category and not included in the total abstraction. Self-supply of households is not covered.

Returned water: The water abstracted from any fresh water source and discharged back into it without use (primarily at mining and quarrying, and construction activities).

Fresh water net abstraction: the fresh water gross abstraction minus returned water.

Water used is a sum of water used by the categories of supply:

Water losses are formed from physical losses in the transport of water, irregular use, errors in measurements, etc. The volume of losses is aggregated for a group of operators in order to avoid the double counting. On RBD level water losses are calculated using a regionalizing factor "supplied water". It is assumed that water losses in self water supply are negligible.

Water generated from point sources: water, which after use leaves the place of use and is discharged into the public sewerage and water bodies. Data is collected through statistical survey on water use, covering more significant water users. Wastewater generated by the households is result from data reported by public water works and estimation. Two categories are distinguished - wastewater and water from cooling processes.

Wastewater discharged after treatment: Amount of wastewater discharged from wastewater treatment plants of the enterprises and UWWTP (according to the latest level of treatment). Wastewater of households with own/independent treatment is also considered as treated.

Water discharged into water bodies: a sum of water discharged by the surveyed enterprises, public sewerage/UWWTP and households with own/independent treatment.

Collected wastewater into public sewerage: calculations are based on data reported by the Public water works and estimations. The quantities from non-point sources (rain-off, drainage and other unallocated water) are also included.

Urban wastewater treatment plants (UWWTP): covered are all operating plants treating wastewater from settlements. Wastewater treatment plants at enterprises, hotels, etc. are referred to a separate category. Design capacity BOD5 (tons O2/day): maximum flows and loads of the influent the facilities are designed for, which conform with the fixed standards.

Public water supply and sewage network - data refer to the network operated by public water supply operators. Also is included the sewage network of municipalities with organized discharge of wastewater in urban wastewater treatment plants. 

Population connected to public water supply/public sewerage and UWWTP - data are the result of survey "Water supply and sewage". It is possible to overestimate the population in settlements with partially build water supply /sewage network, at which only a part of households is connected. Population with independent own wastewater treatment (via septic tanks, cesspools, etc.) is calculated as a difference between the total population and population with a public sewage system.

Measuring water qualities: they are reported by the respondents through water meters, and in case of their absence - using the capacity of the pumps, multiplied by the time of their work; energy consumption of pumps, specific factor, etc.

Statistical unit

Legal entity which corresponding the criteria for coverage of statistical surveys on water.

Statistical population

· Suppliers of water - water supply and sewage operators and irrigation systems;

· Operators of urban wastewater treatment plants;

· Water users according to the criteria for coverage of ‘Survey on water use’;

· Producers of hydroelectricity.

Reference area

Territory of the Republic of Bulgaria

Time coverage

2010 - 2017

Base period

The selection of the base period is determined in accordance with the research objectives and tasks.

Unit of measure

Water quantities: mill..m3/year; thousands m3/year; m3/per capita/day; l/per capita/day

Reference period


Institutional mandate
Legal acts and other agreements

· National Statistical Programme;

· Voluntary providing of national and regional data on water to Eurostat/OECD - gentlemen agreement.

Data sharing

· Data for standard statistical indicators, specialized data according to specific information needs;

· Regular providing of data to the OECD/Eurostat Joint Questionnaire “Inland water” and the Regional Water questionnaire. Annual data are reported every two years.

Confidentiality - policy

· Law on Statistics;

· Regulation (EC) No 223/2009 on European statistics (recital 24 and Article 20(4)) of 11 March 2009 (OJ L 87, p. 164), stipulates the need to establish common principles and guidelines ensuring the confidentiality of data used for the production of European statistics and the access to those confidential data.

Confidentiality - data treatment

Individual data are not published in accordance with article 25 of the Law on Statistics. The publishing of individual data can be performed only in accordance with article 26 of the same law.

Release policy
Release calendar

The date of release of statistical information is indicated in the Release Calendar presenting the results of the statistical surveys carried out by the National Statistical Institute. The statistical information is published once a year.

Release calendar access

The calendar is available on the NSI website: http://www.nsi.bg/en/node/480

User access

The data in the field of water statistics are disseminated and published in accordance with the Law on Statistics and the European Code of Statistics Practice, respecting professional independence and objectivity to transparency, in which all users are treated fairly.

Frequency of dissemination

The data are distributed annually according to the deadlines for disclosure and Rules for statistical data dissemination.

Accessibility and clarity
News release

Annual, according to the Release Calendar presenting the results of the statistical surveys carried out by the National Statistical Institute.


· Environment;

· Statistical Yearbook;

· Statistical Reference Book;

· Regional publication;

· Publications and reports to Eurostat.

On-line database

Comprehensive data of water statistics are available to all users of the NSI website under the heading Environment: http://www.nsi.bg/en/node/5132

Micro-data access

Not accessible.


Information service on request, according to the Rules for the dissemination of statistical products and services.

Documentation on methodology

Data Collection Manual for the OECD/Eurostat Joint Questionnaire “Inland water” Ver. 4.0 (2018)

Quality documentation

Not required.

Quality management
Quality assurance

To improve the quality of data are applied a series of statistical procedures - from data collection to data validation. To determine the coverage of the statistical aggregations are used statistical data from other surveys and administrative data. The methodology is developing in accordance with the requirements for comparability, estimation methods and tools for data collection and procedures for verification are improved.

Quality assessment
User needs

Main users of statistical information of the survey are public institutions, local authorities, companies and others.

User satisfaction

No information. Research on consumer satisfaction is not conducted.

Accuracy and reliability
Overall accuracy
Sampling error
Non-sampling error
Timeliness and punctuality

The data are published according to the terms in the Release Calendar presenting the results of the statistical surveys carried out by the National Statistical Institute.


All publications are published timely, according to the Release Calendar presenting the results of the statistical surveys carried out by the National Statistical Institute.

Coherence and comparability
Comparability - geographical
Comparability - over time

Time series by key indicators at national level are available since 1990.

Coherence - cross domain

Partial, regarding some indicators.

Coherence - internal
Cost and burden
Data revision
Data revision - policy
Data revision - practice

The identified inconsistencies, registration errors and revisions in the primary data are regularly recorded and stored.

Statistical processing
Source data

Specialized statistical surveys - see section 3.3

Frequency of data collection


Data collection

Data are collected through statistical questionnaires in electronic and paper format. Respondents provide the completed questionnaires in regional statistical offices, after which electronic forms are sent to the NSI central office.

Data validation

Validation of primary data is an mandatory stage of the production of statistical information. The first filter for internal coherence of the primary data is laid down in the electronic questionnaires. Validation of the primary data for coherence and conformity is done by regional statistical offices and NSI central office.

Data compilation

Specialized software.


Not applicable.

Download in SDMX 2.1 file format: WATER STATISTICS
Metadata Structure Definition in SDMX 2.1: ESMS_MSD+BNSI+2.0+SDMX.2.1.xml
Download in SDMX 2.0 file format: WATER STATISTICS
Metadata Structure Definition in SDMX 2.0: ESMS_MSD+BNSI+2.0+SDMX.2.0.xml
  • Water abstraction by sources - total for the country, by Statistical Region and River Basin District
  • Water distribution by Public Water Supply - total for the country, by Statistical Region and River Basin District
  • Water used by economic activity - total for the country, by Statistical Region and River Basin District
  • Drinking water used by households from Public water supply, average per capita - total for the country, by Statistical Region and River Basin District
  • Generation and discharge of wastewater - total for the country, by Statistical Region and River Basin District
  • Operating urban wastewater treatment plants, total for the country, by Statistical Region and River Basin District
  • Water supply and sewage network - total for the country
  • Population and water services - total for the country, by Statistical Region, Districts and River Basin District
  • Statistical Reference Book 2009
    Statistical Reference Book 2009
    The National Statistical Institute presents to users of statistical information the annual publication - Statistical Reference Book 2009 in English. It is a concise form of the same issue in Bulgarian.
    The issue is with a new design and enrich contents. For the first time are included methodological and analytic notes towards all chapters. The information is illustrated with a rich graphic materials.
  • Environment 2007
    Environment 2007
    The National Statistical Institute informs users of statistical information that the annual bilingual (Bulgarian-English) publication Environment 2007 (printed and electronic version on CD-ROM) is already available. The publication contains environmental data from NSI statistical surveys in 2007. The main indicators are presented for the 2003 - 2007 period.
    The information is systematized in the following sections:
    • Emissions in the air;
  • Bulgaria 2009
    Bulgaria 2009
  • Statistical Yearbook 2008
    Statistical Yearbook 2008
    The National Statistical Institute has the pleasure to submit to the attention of national and foreign users of statistical information the 76th edition of the Statistical Yearbook of the Republic of Bulgaria 2008. It provides topical statistical information on the demographic, economic and social development of the country for the 2002 - 2007 period in different territorial and classification aggregations and breakdowns.
  • Statistical Reference Book of the Republic of Bulgaria 2008
    Statistical Reference Book of the Republic of Bulgaria 2008
    The National Statistical Institute presents to users of statistical information one of its main publications - Statistical Reference Book of the Republic of Bulgaria 2008 in English. It is a concise form of the same issue in Bulgarian.
    The Statistical Reference Book presents topical information on the demographic processes as well as the economic, social and cultural development of the Republic of Bulgaria for the 2004 - 2007 period.