Relief: The long-term consequences of the devastating tidal waves which have killed thousands in Asia are becoming apparent today.
Rescue efforts are being replaced by a massive humanitarian drive to provide for millions made homeless across the region.
Thousands of people are being put up in schools, churches and community centres and over the next few days and weeks, aid agencies and governments will have to ensure people are fed and have access to clean water.
Mr Andrew Sundersing, relief director for World Vision in Sri Lanka, said: "The first concern is water-borne diseases.
"There are thousands of people who don't have homes and need to build them. In the long term, we need to ensure people have permanent structures to live in."
Oxfam is to send out flood experts to Sri Lanka, one of the worst hit countries.
A spokeswoman for the charity said: "There are a lot of dead bodies lying around and as they start decomposing, the water can easily be contaminated.
The International Federation of Red Cross and Red Crescent Societies is including enough medicine to treat 2,000 cases of diarrhoea in an initial shipment of relief supplies leaving Denmark for Sri Lanka today. In the longer term, the focus will be on rebuilding lives.
Mr Jayath Vincent, communications manager for World Vision in Chennai, India said: "I took a walk down to the beach today, and saw people coming back to pick up what's left of their lives.
"Long-term issues will centre on people having to rebuild their houses and the loss of livelihoods, especially fishermen whose boats and nets have been washed away. World Vision is hoping to offer support to these people."
Mr Nick Young, chief executive of the British Red Cross, said rebuilding was as necessary as short-term relief.
"The emergency response includes medium-term rebuilding and restructuring. If that isn't done, we're only going to have another disaster a few months down the line."
He said existing conflicts in parts of Sri Lanka and Indonesia were also going to make the rebuilding effort harder.
"Conflict areas tend to be areas which are more needy, where basic health care and basic structures don't work, and where access is difficult."
Care International said it was scaling up its emergency response in the worst affected areas.
In Sri Lanka, teams have been sent to assess the damage and to help evacuate vulnerable communities to higher ground. Over the next two days it will provide food for 14,000 people affected in the Batticaloa district, with similar assistance being sent to Jaffna, Mullaitivu, Trincomalee, Ampara and Hambantota. The agency is also planning to assist with the distribution of relief supplies.
The agency has sent an assessment team to the Indian coastal city of Chennai with water purification to address one of the most immediate needs - clean drinking water.
In Indonesia, it will distribute 100,000 safe water system bottles, which can each provide enough clean drinking water for a family for a month. In Thailand it is carrying out a rapid assessment for relief operations in the worst affected coastal areas.