Like most warblers, it is insectivorous, however, it will eat other small food items such as berries. The Aquatic Warbler is a migratory bird and spends cold winters in west Africa. After many years of uncertainty, the wintering grounds of much of the European population were finally discovered in Djoudj National Bird Sanctuary, Senegal, with between 5-10,000 birds present at this single site. The Aquatic Warblers south-westerly migration route means that it is regular on passage as far west as Great Britain.

After mating and gestation, 3 – 5 eggs are laid in a nest in low vegetation. The Aquatic Warbler is highly promiscuous, with most males and females having offspring with multiple partners. The eggs of the aquatic warbler are brown and densely spotted with a yellowish grey.

The Aquatic Warblers song is a fast, chattering ja-ja-ja punctuated with typically acrocephaline (warbler) whistles.