Question: roughly how many lives have you changed by building the pump?

Ken Gibbs answered on 14 Mar 2012:

Well, we think that in Bangladesh, for instance, one pump serves around 150 people. The trouble is that until everyone has reasonable access to a pump, the number around each pump will be somewhat more, like 200 or thereabouts. On that basis, and knowing that there are 1 million pumps in the field throughout the world, we could be affecting/changing the lives of up to 200 million people but probably rather fewer than that, say, 160 to 170 million. This is quite a few people because it represents three times the present population of England !