Public water supply and sanitation in the United Kingdom is characterised by universal access and generally good service quality. A salient feature of the sector in the United Kingdom compared to other developed countries is the diversity of institutional arrangements between the constituting parts of the UK (England and Wales; Scotland; and Northern Ireland), which are each described in separate articles, while this article is devoted to some common issues across the United Kingdom. Access Access to improved water supply and sanitation in the UK is universal. In 2015, 100% of the population had access to improved water supply and 99% of the population had access to "improved" sanitation. Source: WHO/UNICEF Joint Monitoring Program (2008) Water sources According to the Environment Agency, total water abstraction for public water supply in the UK was 16,406 megalitres per day in 2007. Groundwater contributes 30 per cent of public supply water in England. In Wales and Scotland groundwater provides about five per cent of public supply. The majority of the UK's abstraction of surface water is from reservoirs, where rainwater is transported via rivers and streams and contained in an artificial or natural lake until it is required. Responsibility for water supply and sanitation Policy and regulation In England and Wales the economic regulator of water companies is the Water Services Regulation Authority (Ofwat). The Environment Agency is responsible for environmental regulation, and the Drinking Water Inspectorate for regulating drinking water quality. The economic water industry regulator in Scotland is the Water Industry Commission for Scotland and the environmental regulator is the Scottish Environment Protection Agency. Drinking water standards and wastewater discharge standards in the UK, as in other countries of the European Union, were determined by the EU (see Water supply and sanitation in the European Union) before Brexit. Service provision In England and Wales water and sewerage services are provided by 10 private regional water and sewerage companies and 13 mostly smaller private "water only" companies. In Scotland water and sewerage services are provided by a single public company, Scottish Water. In Northern Ireland water and sewerage services are also provided by a single public entity, Northern Ireland Water. Employment Total employment by UK water companies amounted to 41,000 full-time equivalent jobs in 2012/13, according to an analysis by the consulting firm Deloitte. In addition, 86,000 jobs were supported indirectly. Financial aspects Tariffs According to a 2006 survey by NUS consulting