Maldives rainwater harvesting innovation could become model for other island nations

view from the coast
Runoff from buildings is being stored and purified as a freshwater source. UNDP Photo

When Nasreena Ahmed was younger, the residents of Ihavandhoo Island in the Maldives could rely on groundwater for bathing, drinking, and cooking. Today that is no longer the case – years of population growth, ineffective sewage systems, and encroaching salt water have made the groundwater unsafe to use

Now, Ahmed, 45, and her family of eight rely on a 2,500-litre rainwater tank to collect water for their household. In months with little rain, the tank runs dry and the family has to buy costly bottled water.

The Maldives is the world’s lowest-lying nation. Its highest point is only 2.4 metres above sea level. The atoll-nation’s islands are extremely vulnerable to flooding and coastal erosion, and rising seas and more extreme weather also threaten the scarce freshwater resources.

HIGHLIGHTS

  • The Maldives is the world’s lowest-lying country, making it vulnerable to flooding, coastal erosion, and dwindling freshwater supplies
  • The government of Maldives, with the support of UNDP, is piloting a new water management system on three islands that suffer water shortages.
  • The system will combine new reverse osmosis desalination plants with a network of rainwater harvesting and storage tanks.
  • When completed in October 2015, the system will increase total freshwater storage capacity and secure freshwater for over 6,200 people.

The government of the Maldives, with support from UNDP, is piloting a water management system on the densely populated island of Ihavandhoo, with similar projects in the works on Mahibadhoo and Gadhdhoo. It will include a reverse osmosis (RO) plant for desalination and networks of connected rainwater tanks to safely store and treat water for use during the dry season. A small number of recharge pits will also be installed on each island near the RO plant facilities and rainwater collection tanks to capture the overflow from the tanks to use for slow and controlled recharge of the aquifers.

With land for rainwater catchment scarce, the project is using buildings themselves as catchment areas. The idea is to create a network of public and private buildings that normally discharge excess rainwater, and instead collect that water into interconnected water harvesting tanks. Rainwater collected this way is then brought to a central water supply plant where it is treated and pumped back into a distribution network, and eventually into people’s homes.

When completed, the integrated water supply systems will increase total freshwater storage capacity and secure freshwater for over 6,200 people on the three islands. Moreover, the design allows for future expansion of the network, as more households and buildings are ready to connect. The system is also designed to enhance artificial groundwater recharge, improve the quality and quantity of water in aquifers, reduce contamination from household effluents, and prevent runoff into sensitive reef ecosystems.

A ‘willingness to pay’ survey and a cost-benefit analysis showed that the system can operate at an affordable cost at or below current market rates. The government of the Maldives manages the project and will train technicians to maintain the water system once the project is complete.

Ms. Ahmed is optimistic about the project, but her desire for results is clear: “I think the project is very good, and finally we are seeing something happen, but I will only say this will happen when we see it,” she said in an interview with Transparency Maldives.

“The most important thing for us is to have a system that is sustainable,” said Project Manager Najfa Shaheem Razee. The local people have been at the centre of the planning process, he says.  

The local council chose the site for the RO plant, for example, and played an important role in obtaining permission and arranging compensation for nearby palm owners whose coconut palms would be cut down.

The president of the council, Mohamed Sameer, was positive about the process. “The government came to use with a vision, but they included our ideas. This is a good design for our island,” he said in an interview. He also noted that two of the three technicians for the RO plant have been recruited locally, which will help make the project more sustainable in the long-term.

The rainwater-storage network and desalination plant are expected to secure between 15-50 litres/day/person by 2030. These elements address a number of critical climate and non-climate related problems and provide a model that other islands can replicate. In fact, there is a number of government funded, new water supply initiatives already replicating this hybrid model with integrated functions of water harvesting, purification and groundwater recharge. For example, Maldives Water and Sewage Company (MWSC) is already constructing the similar system on the island of Dhuvaafaru to extend the service to additional 4,000 people.