What increases the risk of dehydration in children?

Lack of water: The risk of dehydration goes up with exposure to hot and dry conditions which enhance perspiration to keep the body cool. This leads to water loss. Exercise does the same thing. Any set of circumstances with sweat increases the risk of dehydration. The general rule is that if you feel thirsty you are already dehydrated! so supply your children with free access to water.

Size matters: Kids are not small adults. They have a higher percentage of water to body mass.They have a higher baseline metabolism. They are more prone to gut viruses that adults have developed immunity to. When they get sick, they can shut down and refuse to drink while an adult knows s/he must.Dehydration is a common reason for hospitalization in kids for those reasons.