The United Nations Children's Fund (UNICEF) says more than 100,000 people in Vanuatu have no clean drinking water, more than a month after Cyclone Pam struck.
UNICEF said two thirds of the archipelago's water and sanitation infrastructure had been damaged or destroyed and most wells were contaminated.
UNICEF Vanuatu field office chief Ketsamay Rajphangthong said as a result there were lots of risks of people contracting diseases, especially diarrhea.
Cyclone Pam destroyed homes and infrastructure, leaving 11 dead and affecting the majority of the 252,800-strong population of Vanuatu.
The agency has been providing water purification tablets and plastic sheets for rainwater collection as a temporary substitute for the 68 percent of rainwater harvesting structures that have been damaged.
Ms Rajphangthong said fixing the damage was urgent because women and children have to walk to shower facilities and toilets further from home, where they may lack privacy and expose themselves to abuse.
UNICEF needs $US1.5 million to close the gap between donations and its appeal target so it can finish the repairs.