The TV ad, created by Watson Phillips Norman, showed images of several distressed children and a voice-over stated: "If you do just one thing today, please watch this appeal. In the next three minutes, 10 children will die from dirty water.
"They'll die from deadly diseases like cholera and dysentery. They'll die because they've simply nothing else to drink."
It received six complaints from viewers who said the ad was inappropriately scheduled, because their children had seen it on children's channels and been upset by it.
WaterAid said that it was concerned to hear that children had been upset by the ad, but that it had also received a number of positive messages from parents who had thanked them because the ad helped to inform their children about development issues.
The charity also explained that due to an error at its media buying agency the ad had not been scheduled as it had intended. It had a much higher spend on the Cartoon Network and Jetix children's channels and the erroneous bookings had appeared over a concentrated period of time.
WaterAid said that without the error they would have had a much lighter presence on the two channels and it offered apologies to parents who had objected to the number of times the ad had appeared on those channels.
The charity asked for the Cartoon Network and Jetix to be removed from its media schedules for the next three months.
Clearcast said that it had not applied a timing restriction for the ad because there was nothing in the visuals that it felt was a problem.
The advertising watchdog did not uphold the complaints. It accepted that some children might find the subject matter distressing, but considered that most were likely to be in the company of an adult who could explain it to them.
It also considered that although the images and voiceover were about serious issues and showed some images of children in distress, the ad did not use shocking claims or images merely to attract attention. It made clear that the issue was serious and the action that could be taken to prevent it.
The ASA concluded that a scheduling restriction in order to direct it away from children was not warranted on this occasion and that the ad had been scheduled appropriately.