Strengthening Water Resilience through Diversified Sources and Conservation

The Marina Reservoir is fed by five rivers running through the heart of Singapore and can meet about 10% of the city’s water needs. Photo credit: PUB, Singapore’s National Water Agency.

Share on:           


To ensure water security, Singapore has diversified water supply over the last five decades and actively promoted water conservation.


Singapore saw a critical need to develop a sustainable water management strategy quiet early. It is an island-state with few natural water-storage resources. It realized how vulnerable it was, especially after severe droughts led to water shortages in the 1960s.

Through diversification, innovation, and investment in technology, Singapore has strengthened its water resilience significantly over the last 50 years.

This case study was adapted from Urban Solutions of the Centre for Liveable Cities in Singapore.


Singapore is a densely populated city-state with over 5.6 million people in an area of just 719 square kilometers. Although it receives an average of 2,300 millimeters of rainfall each year, it has limited land to collect and store rainwater. With neither big rivers nor lakes, Singapore was ranked 170th out of 193 countries for availability of natural water resources in the 2006 United Nations World Water Development Report.

During the early days of Singapore’s independence in the 1960s and 1970s, it relied mainly on water imported from neighboring countries to meet its needs. This meant that if a drought affected Singapore and its neighbors, the city would be extremely vulnerable to water shortages. Singapore would then also be at the mercy of its neighbors for survival.

In 1960 and 1963–64, severe droughts did hit Singapore. With the city’s post-war population boom and underinvestment in infrastructure, the extreme dry weather led to water shortages, and water rationing had to be carried out. Providing an adequate water supply became a top priority, and thus began Singapore’s push to become self-sufficient in water.

Water rationing in the 1960s. Photo credit: PUB, Singapore’s National Water Agency


Singapore took its first significant step toward a sustainable water management system in 1971 with the formation of the Water Planning Unit under the Prime Minister’s Office. This was followed by the first Water Master Plan in 1972. The plan envisioned a diversified water supply over the next half-century, which has become known as the Four National Taps: local catchment water, imported water, reclaimed water, and desalinated water.

Maximizing existing supply

A key pillar of Singapore’s long-term water strategy was to harvest and store as much rainwater as possible. This required the creation of unprotected, urbanized water catchments. However, many of the rivers that could be dammed for reservoirs had been polluted by economic and residential activities.

The government undertook a massive cleanup of the Singapore and Kallang Rivers in the 1970s. Pollutive activities were relocated, squatters were resettled into proper housing, and legislation was introduced to protect catchments.

Today, two-thirds of Singapore’s land area collects rainwater, which is then channeled into 17 reservoirs.

The reservoirs at Punggol, Serangoon and Marina were created by damming rivers. In the heart of downtown Singapore, Marina Reservoir collects rainwater from some of the oldest and most densely built-up areas of the island city.

Singapore is the only city in the world where urban stormwater harvesting is carried out on such a large scale. Nonetheless, the local catchment supply remains vulnerable to drought. Alternative sources of water that are less rainfall-dependent are therefore required.

Transitioning to unconventional water sources

Singapore first explored water reuse in the 1970s as a means of diversifying its water supply, but shelved the idea due to high costs and the unproven reliability of membrane technology then. By the 1990s, the performance and cost of membrane technology had improved significantly, and other countries were starting to use it in water treatment and reclamation.

In 1998, the Public Utilities Board (reconstituted in 2001 as PUB, Singapore's national water agency) tested the latest membrane technology in water reclamation for potable purposes. Two years later, the agency commissioned a full-scale demonstration plant that could produce 10,000 cubic meters of ultra-clean, high-grade reclaimed water a day.

In 2003, PUB introduced the high-grade reclaimed water as NEWater. To ensure the highest quality, a comprehensive water sampling and analysis program was implemented, benchmarking the results against the World Health Organization and the United States Environmental Protection Agency’s drinking water standards.

NEWater is primarily for non-domestic use in wafer fabrication parks, industrial estates, and commercial buildings, and to top up reservoirs during dry months. It allows Singapore to reduce its dependence on rainfall, enabling every drop to be used and reused.

As membrane technology continued to advance, desalination became a natural choice for the island in its quest for water self-sufficiency. In 2005, Singapore opened its first desalination plant with a capacity to produce 136,000 cubic meters per day. A second plant commissioned in 2013 added another 318,500 cubic meters of capacity per day. To prepare against dry spells, which may become more prolonged due to climate change, five desalination plants are expected to be operational by 2020.

As rainfall-independent sources, NEWater and desalinated water are key to building up Singapore’s drought resilience. By 2060, these two sources will be able to meet up to 80% of total water demand.

The NEWater Visitor Centre offers an educational and interactive multimedia experience on Singapore’s water story and water reclamation. Photo credit: PUB, Singapore’s National Water Agency.

NEWater is produced by further purifying treated used water using advanced membrane technologies. Photo credit: PUB, Singapore’s National Water Agency.

Managing demand

Demand management is equally essential to ensuring a sustainable water supply. Aware that Singapore’s success in water supply management may breed complacency, PUB relies on a multi-pronged approach to promote conservation: pricing water correctly, mandating standards for efficiency in water usage, and facilitating programs to encourage water conservation.

In the long term, non-domestic use is expected to make up 70% of total water demand. Singapore therefore encourages industries to adopt water-efficient systems and processes, and views this as an opportunity to grow the local water industry by spurring the co-creation, test-bedding, and adoption of water-efficient technologies.

Children in primary school learn about water conservation. Photo credit: PUB, Singapore’s National Water Agency.


Singapore has come a long way from its water-rationing days. Today, its people enjoy clean drinking water at the turn of a tap. The country’s water management achievements have gained global recognition. PUB received the Stockholm Industry Water Award in 2007 and the United Nations Best Practices Award, “Water for Life,” in 2014.

However, the threat of a prolonged drought remains a cause for concern. In the past decade, Singapore experienced two dry spells—in 2010 and 2014. February 2014 was the driest month since 1869, with only 0.2 millimeters of rainfall recorded compared with the mean February rainfall of 161 millimeters.

During the dry spell in 2014, Singapore was able to meet its water needs by running its desalination and NEWater plants at nearly full capacities. Fortunately, regular rainfall resumed after three dry months. A prolonged drought would have put a strain on the system.

The journey toward water sustainability has not ended, and PUB continues to update its water supply strategies, invest in research and innovation, and promote water-consciousness.

As a global water hub, Singapore now hosts over 180 water companies and more than 20 research centers actively pursuing a range of water infrastructural and R&D work. Water conservation efforts have also paid off as Singapore’s daily per capita domestic water consumption fell from 165 liters in 2003 to 148 liters in 2016. PUB wants to reduce this further to 140 liters by 2030.


Tan Gee Paw (2015) Four National Taps: Singapore’s Water Resilience StoryUrban Solutions, Issue 7: Resilience. Published Jun 2015. The Centre for Liveable Cities, Singapore.

Centre for Liveable Cities (CLC)
A global knowledge centre for liveable and sustainable cities

The mission of the Centre for Liveable Cities in Singapore is to distil, create and share knowledge on liveable and sustainable cities. CLC’s work spans four main areas—Research, Capability Development, Knowledge Platforms, and Advisory. Through these activities, CLC hopes to provide urban leaders and practitioners with the knowledge and support needed to make our cities better.

Leave your question or comment in the section below:

The views expressed on this website are those of the authors and do not necessarily reflect the views and policies of the Asian Development Bank (ADB) or its Board of Governors or the governments they represent. ADB does not guarantee the accuracy of the data included in this publication and accepts no responsibility for any consequence of their use. By making any designation of or reference to a particular territory or geographic area, or by using the term “country” in this document, ADB does not intend to make any judgments as to the legal or other status of any territory or area.