By Engr. Edgar Mana-ay
Let’s start with potable water supply comparison. Metro Manila (population: 16.3 million) is supplied with 4 million cubic meters per day (cmd). One cubic meter of water is 1,000 liters and that’s roughly 250 liters per person per day.
Las Vegas with 2.2 million people, uses 2.3 cmd of water and that’s 1,000 liters of water per person per day; and Singapore with a land area of 725 square km., a little bigger than Guimaras with 5.7 million population, consumes 113 cmd or nearly 20,000 liters of water per day per person!
Of course, the island of Singapore is highly industrialized (the biggest oil refineries in Asia are located in Jurong Industrial estate of Singapore), hence the tremendous water consumption not only for industries and the populace but for tourism (as in Sentosa island) as well.
It is a miracle story how a small, highly industrialized country like Singapore can cope with its potable water demand. Even if it can supply sufficient water to its constituents, Singapore is on top of the list of countries expected to be the most water-stressed by 2040. In the tropics where rain is bountiful, water supply for any locality is proportional to the land area where it is located. Singapore’s limited land area and the competing demand for housing, industry and infrastructures mean that the island city-state cannot set aside large areas of open land for watershed, catchment and storage.
In a given locality, the bigger the land area it encompasses, the more rain it receives and CAN use, depending on how disciplined the populace and government are in taking good care of the watershed. This is a basic concept in hydrogeology and one does not need to enroll in a geology school to understand this. This is also the reason why island barangays in Concepcion, Iloilo such as Pulopiña, Igbon, Salvacion, and Balidian suffer from perennial potable water shortage that impedes the tourism industry in these islands. These small islands are actually undersea volcanic mountains which jutted out from the seafloor and in millions of years, the volcanic rocks is now covered by a thin layer of soil and vegetation, hence catching the rain and storing is fragile and minimal.
It is a marvel that despite the hydrogeology handicap of Singapore, its focus on water supply management is NOT SURVIVAL BUT SUSTAINABILITY! Rising water demand has driven Singapore to explore and implement ALTERNATIVES to NATURAL freshwater supply. High-grade reclaimed water, known as NEWATER was introduced to the supply chain in 2003. Newater is produced by further purifying treated sewage water (or “used water”) using advanced membrane technologies such as microfiltration and reverse osmosis (RO), followed by ultraviolet (UV) disinfection. While seawater is limitless, desalination cost to convert it to freshwater is still higher than Newater.
Singapore water demand of 113 cmd (million cubic meters per day) is met by four sources: A) water from local rain catchment system – 20%; B) Water imported via pipeline from Johor Malaysia but will expire in 2061 – 50%; C) NEWater – 20%; and D) Desalination water from the sea – 10%.
Known as the “Four National Taps”, these four sources are integrated to form a robust, diversified, and sustainable water supply that will reliably meet water demand well into the future. The most critical is the supply from Malaysia because if relations between the two countries turn nasty, Malaysia will just turn off the valve and half of Singapore’s water supply is gone!
Against this background, Singapore’s water policies are guided by three KEY STRATEGIES:
- COLLECT EVERY DROP – since Singapore is a small island, 2/3 of its area is designated as water
catchment, much of which is urbanized! Strict land-use planning and environmental control are in place to collect surface runoff and minimize pollution. Stormwater infrastructure is separated from sewage infrastructure.
- REUSE WATER ENDLESSLY – since the inception of NEWater in 2003, the components of the
entire water loop (rainwater collection and stormwater management, water treatment and distribution, sewage collection and treatment and water reuse) has been managed by a single national water agency.
- DESALINATE MORE WATER – Desalination is a natural option for Singapore, but despite
advances in membrane technology, power cost is still high in pushing seawater through a membrane that is constantly fouled up by phytoplankton. They should look at Israel Sorek Desalination plant where power cost is reduced by using porous lava stones as its first line of filters to capture the microorganism before they reach the membrane.
Since we are located in the topics with tremendous rainfall, we are NOT supposed to have water supply problems because of the vastness of open lands that can amply serve as rain catchment or watershed to sufficiently supply the entire populace with rainwater. But why oh why do we have this perennial water shortage special in Metro Iloilo? I have shown the map of Tigum and Aganan rivers and watershed emanating from the mountains of Maasin and draining towards Iloilo City to my hydro-geology friends in Manila and the usual remarks: “Pare wala kayo problema sa tubig sa Iloilo City”! True enough from the hydro-geology experts that by just looking at the map, there should be no dearth of water supply for Metro Iloilo.
What were the “wrong mistakes” that we have been doing and have never done it right? If Singapore can capture 90% of its rainfall, we can only store 10% in the ground and manmade “alebe” or reservoir! The 90% causes floods, then flows via swollen rivers towards the sea where we cannot use it anymore. Singapore maintains two sets of infrastructures: one to gather stormwater towards a storage facility and another one for sewage into another reservoir. Both are then subjected for further processing into NEWater. We have NONE for both. Singapore maintains a SINGLE national water agency to ensure that planning, water infrastructures development and operations are seamlessly integrated. Here we have the NWRB, DENR, DPWH, LWUA and a host of other agencies all dipping their fingers into our water supply system with no tangible results. Are we a people who when left to ourselves become unfit to govern ourselves?
Note: The author is a Professional Member of the American Water Works Association (AWWA).
