On Sunday, two mass choirs of 500 children and 600 adults will sing to raise money for the charity WaterAid.

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The organization will also use Skype to conduct video calls with volunteers (from Oxfam and partners like WaterAid) in Cameroon, Pakistan and Dakar through Friday, says Oxfam digital strategist Jason Wojciechowski.

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Two UK development agencies, Tearfund and WaterAid, said the agreement to halve the number of people without access to sanitation was "the first milestone in a long fight to halt the millions of deaths caused by preventable disease".

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