Most of those people have since returned home.
Ramya Siriwansa, deputy director of emergency operations at the National Disaster Management Centre, said: "A water tank has broken its banks in Batticaloa. There are 175,025 people displaced.
"Many are with friends and relatives, others are in camps and sheltering in schools and temples."
Flooding and displacement are common in Sri Lanka, where a southern monsoon batters the island between May and September, and a northeastern monsoon runs from December to February.
Batticaloa, on the eastern seaboard, was badly affected by the 2004 tsunami. The third anniversary of a disaster that left 35,000 people dead and missing in Sri Lanka alone is two days away.
Flooding and drought are cyclical in the Indian Ocean country.
In January, about 60,000 people were displaced by floods, with the southeastern district of Hambantota badly hit.
More than a dozen people were killed by landslides in the central hills at the time, hundreds of houses were damaged and thousands of people were stranded in makeshift welfare centres.