The military were seen delivering food to people whose homes were waist-deep with water. Navy boats were out rescuing marooned residents.
Sri Lanka's southern and western plains were the most effected in the last 72 hours due to the monsoon rains.
Heavy downpours caused by cyclones have raised water levels in irrigation and hydro-electric reservoirs.
Authorities released the excess water into rivers which caused water levels to rise and over flow into low-lying areas.