The UN Office for the Coordination of Humanitarian Affairs (OCHA) released their updated Situation Report today (PDF). The report reveals that the distribution of shelter materials has reached 90 percent of those in need, and is on track to reach 100 percent by the May 1 goal. Nevertheless, worries remain that even with tarps, the rainy season could still cause an immense disaster. OCHA notes that:
With only 20,243 tool kits reported as distributed and 81,000 households with ropes and fixings provision, this remains a vital gap in the response. A large number of emergency shelters constructed will require strengthening for the rainy season.
After some of the heaviest rains since the earthquake this past weekend, the International Federation of the Red Cross (IFRC) visited sites and found that while most shelters held up, some had collapsed. In one camp, the IFRC noted that:
Among the most affected people here are those whose self-made shelter leaked or collapsed during the rains. Many spent the night trying to sleep sitting up and spent their day repairing shelters or putting down gravel to improve drainage.
One of the biggest concerns for the upcoming rainy season if the issue of sanitation. The recent OCHA report notes that only 5,347 latrines have been built, compared to the 11,000 that the plan had called for by mid-April. By end-June there are plans for 21,000. Construction of latrines has been slow, the American Red Cross' three month report reveals that the global Red Cross network has only built 200 latrines in the past month. In addition, the previous OCHA report (PDF) said that:
Oxfam has decided, in response to the complaints about inappropriate design of latrines (resulting in one third of them not being used), to start constructing and repairing latrines according to international accepted standards (including separation of latrines for men and women, covered bathing facilities among other aspects).
Furthermore, with the onset of the rainy season there is an increasing risk of water borne diseases, which will only be exacerbated if latrines are flooding. The IFRC noted after the heavy rains this weekend that:
At Camp Mais Gate 2, aid workers with the Spanish Red Cross and the Haitian Red Cross worked together to remove water from blocked ditches and human waste from latrines that were near capacity and beginning to overflow, putting people at risk for contamination.

"Sludging latrines is hard and disgusting work, but if we do not do this before more heavy rain comes, then they will be completely full and the content will spill into the camp," said Jesus Baena, a sanitation delegate with the Spanish Red Cross.
The Red Cross says they are beginning to replace the pit latrines that have been built with flood-proof latrines.