The quantity of fresh water supply is subject to seasonality due to predominant reliance on rainfall, low rainwater storage capacity and poorly constructed communal and household rainwater harvesting systems. In addition, poor maintenance of water and wastewater management at the household level can contribute to low volume and scarcity. When household supplies are depleted, the community depends on the government to transport water to their homes from national reserves.
There is biological and chemical pollution of marine and ground water from wastewater seepage, solid waste leachate, household chemicals, and waste oil from garages and other light industry. Sewage and animal waste (especially pigs) contribute to the direct and indirect contamination of the ground water and lagoon on Funafuti and to a lesser degree in the populated outer islands of the rest of Tuvalu. Eutrophication supports the growth of algae in Funafuti lagoon, and the reef on the ocean side of the island is severely degraded. Destruction of marine habitat has been observed in the Conservation Area on the far side of the lagoon. The Conservation Area offers significant potential for eco-tourism and this is being threatened by the current lack of effective waste management. Fish habitat, stocks and biodiversity are also threatened. Groundwater on Funafuti is no longer fit for human use, but it continues to be used for some household needs especially during drought. (SOPAC 2007b, SOPAC 2007c)
The low-lying nature of the atoll islands and their limited groundwater resources make Tuvalu particularly vulnerable to sea-level rise. Combined with the high sensitivity of rainfall variability to ENSO cycles, Tuvalu’s long-term freshwater resources are highly vulnerable. (Duncan 2011)