The star visited poor communities in Ghana, where a new drive by cosmetics giant Procter & Gamble is in place to make dirty water drinkable with the use of purification sachets.
Chisholm met youngsters whose lives have been transformed by the scheme and is now urging fans to support the initiative.
She says, "I've been on charity trips to Africa before. They can be harrowing, but this one was really positive and inspiring. Already it's changing people's lives.
"When we first arrived, three of the girls took us down to the local water supply, which is basically a big lake shared with animals, so that water can be very dangerous.
"Using the sachets, in half an hour the water goes from back to clear. We drank it as well - it's completely and utterly safe."