The floodwaters in the southwestern Somali district of Dolow may have started to recede -- for now -- but distraught families who have lost their homes, their livelihoods in the muddy deluge are now at risk of potentially fatal disease.

Shukri Abdi Osman, a 34-year-old mother of three, is sheltering in a camp for the displaced in Dolow with her children, among around 700 families forced to flee as flash floods engulfed many parts of town.

"I have never seen such devastating floods before, everything happened quickly. When we realised the water was coming it was too late to collect all our belongings. We left our houses at midnight and all we were able to grab was our children," she said.

As the family breadwinner, Osman said she thought she had a bright future, with plans to expand her flourishing fruit and vegetable kiosk in the Garbolow neighbourhood of Dolow, which lies on the Juba River near the Ethiopia border.

"But I ended up here in this IDP settlement hopelessly waiting for the situation to change. My business is gone, my property is destroyed, and my house engulfed in water," she said, as she struggled to light firewood to cook a meal for her children.

- 'Leaking septic tanks' -

And now disease is posing a threat to her family.

"The toilets were destroyed and even the tap water is now mixed with the dirty flood water which includes leaking septic tanks," she said.

"The situation is very tough now in this camp with my daughter feeling unwell, she might have already contracted malaria and typhoid."

Somalia's government has declared a state of emergency over what the United Nations has called "once-in-a-century" flooding, with almost 100 lives lost across the country and 700,000 people made homeless.

Torrential rains linked to the El Nino weather phenomenon have lashed the Horn of Africa on the heels of the worst drought in 40 years that drove millions to the brink of famine in Somalia.

It is considered one of the most vulnerable countries to climate change, locked in a vicious cycle of drought and floods.