<prompt> In Target 10 of Goal 7 of Millennium Development Goal, access to an improved water source mean?Availability of at least 20L water person day from a source within 1 km of dwellingAvailability of at least 20L water person day from a source within 1.5 km of dwellingAvailability of at least 15L water person day from a source within 1 km of dwellingAvailability of at least 15L water person day from a source within 1.5 km of dwelling  <response>: Propoion of population with sustainable access to an improved water source, rural G7.710.130 : improved water sources means household connection, public standpipe, borehole, protected dug well, protected spring, rainwater collection. Access means the availability of at least 20 litres water per person per day from a source within one kilometre of the users dwelling. Ref: Parks textbook of Preventive and Social Medicine, 21st edition, page-831 