Drowning was the biggest killer of children aged under 15 from 2006 to last year, according to the Public Health Ministry.
Minister Piyasakon Sakonsatayatorn said drowning beat out dengue and road accidents as the main cause of death of children younger than 15.
From 2006 to last year, 10,923 children drowned, he said.
Most cases involved swimming accidents or falling into water retention facilities, such as excavated ponds and reservoirs.
Water in excavated ponds is usually deep, he said. Some ponds have no fences, warning signs or any life-saving equipment nearby.
Of the children who drowned, more than 400 were under five who died in buckets, tubs and fish tanks filled with water in their homes, according to the minister.
Citing World Health Organisation (WHO) figures, the minister said 372,000 people worldwide drown every year on average, half of whom are 25 years old or younger.
Drowning ranks third behind meningitis and Aids as the main cause of death among children under 15 worldwide.
Parents and guardians should tell their children not to venture too close to water, Dr Piyasakon said. They must be taught not to try to retrieve items dropped into water or lean into water jars, he said.
Of the 8.3 million children aged 5-14 nationwide, only two million can swim, according to the ministry.