1.2.5 Sustainable water supply systems and climate variability and change Reliable estimates of sustainable groundwater extraction and pumping rates have only been determined for a small number of locations in Tarawa and Kiritimati. The sustainable rates of groundwater extraction from all groundwater lenses in all inhabited islands and particularly planned growth centres need to be assessed particularly in terms of the potential impacts of climate variability and change. At present the maintenance and operation costs of urban and rural water supply systems are not covered by water charges to consumers and the systems are not economically sustainable and there are no conservation messages in current fixed fee tariffs. 1.2.6 Protection of freshwater sources