One of the service obligations of Manila Water is to provide potable drinking water to its customers in the East Zone concession area.
Manila Water obtains 97 percent of its raw water from rivers, streams and lakes, which represent high quality sources of surface water. Given its heavy reliance on surface water, protecting the watersheds that feed into the rivers and reservoirs is essential to its operations.
The Angat Reservoir and Dam are located 38 kilometers north of Metro Manila at the Angat River in San Lorenzo, Norzagaray, Bulacan. The facilities were constructed from 1964 to 1967 and have been operational since 1968. They have multiple functions:
- To supply the domestic and industrial water requirements of residents in Metro Manila;
- To provide irrigation to about 31,000 hectares of land in 20 municipalities and towns in Pampanga and Bulacan;
- To generate hydroelectric power to feed the Luzon Grid; and
- To reduce flooding to downstream towns and villages.
The principal river, Angat River, originates from the Sierra Madre Mountains. It has three major tributaries namely the Talaguio, Catmon and Matulid Rivers. The Angat Watershed has a moderate to intensive forest cover and has an area of about 568 square kilometers, which receives an average annual rainfall of about 4,200 millimeters.
The Angat Dam is a rockfill dam with a spillway equipped with three gates at a spilling level of 212 meters. It supplies 98 percent of Metro Manila’s water needs with a storage capacity of about 850 million cubic meters. Water supply to the MWSS is released through five auxiliary turbines where it is diverted to the two tunnels going to the Ipo Dam. Every second, the dam releases 46 cubic meters of water (CMS).
Angat usually stores enough water to give the city a 30-day worth of supply. This supply can be severely affected during droughts caused by El Niño. When Angat Dam breaches its critical level mark of 160 meters, raw water allocation for Metro Manila may be reduced within 36 to 40 CMS.
The Ipo Dam is a gravity-concrete dam located about 7.5 kilometers downstream of the Angat Dam in Bulacan. It was completed in January 1984 with a maximum storage capacity of 7.5 million cubic meters with a total catchment area of 6,600 hectares.
The maintaining level of the dam is at an elevation of 101 meters and it has seven radial floodgates. The watershed topography is characterized by mountainous terrain similar to the Angat Reservoir Watershed with moderate forest cover. The watershed has an area of about 70 square kilometers and receives an average annual rainfall of 3,500 millimeters. Tributaries to the Angat River at this section include the Ipo, Sapa Pako and Sapa Anginon Rivers. These tributaries drain into the Angat River from the eastern section of the watershed.
The Ipo dam is primarily a diversion dam, bringing water from the Angat and Ipo Rivers into tunnels that lead to La Mesa reservoir and Balara Filtration plants. From the Angat Dam, water flows through two concrete diversion tunnels down to the Ipo Dam. The Ipo Dam serves as an intermediate intake and water is then conveyed through three intake structures at the dam going to three connecting tunnels. Water from the three tunnels flows to three settling basins in Bicti, Norzagaray which are connected to five Bicti-Novaliches aqueducts. The five aqueducts can deliver a maximum capacity of 4,500 million liters per day at the Novaliches Portal. At the Novaliches Portal, most of the water is conveyed through three open channels going to Balara Treatment Plants.
La Mesa Dam
The La Mesa Dam is an earth dam located in Novaliches, Quezon City. It was first built in 1929 and then further raised in 1959 to a maximum storage capacity of 50.5 million cubic meters. Overflow level of the dam is at an elevation of 80.15 meters. The watershed has an area of 27 square kilometers, which receives an average annual rainfall of 2,000 millimeters.
The La Mesa Dam serves as a primary sedimentation basin. It has a storage capacity equivalent to 19 days of Manila Water’s supply requirements. During dry months, the La Mesa Dam may also serve as a buffer or reliability dam to provide supply. La Mesa Dam's critical level is pegged at 69 meters above sea level.
The La Mesa Dam has three intake structures, with connecting aqueducts to the Balara and East La Mesa Treatment Plants.
Manila Water operates three water treatment facilities — Balara Filter 1, Balara Filter 2 and East La Mesa, all located in Quezon City.
Balara Treatment Plants
Water travels approximately 34 kilometers from Angat to the Balara Filtration Plants. Balara Filter 1 has been operational since 1935 and has a treatment capacity of 470 million liters per day, whereas Filter 2 has been operational since 1958 and has a treatment capacity of 1,130 million liters per day.
In total, the Balara Filtration Plants filter the equivalent of almost 7 billion glasses of water each day equal to a combined production of an average of 1,600 million liters of drinking water per day.
East La Mesa Treatment Plant
The East La Mesa Treatment Plant located in Payatas, Quezon City began operations in June 2012. It has a capacity of treating 150 million liters of water per day. It supplies water to far-flung expansion areas in the Rizal province, improving the supply balance of the entire network.
Cardona Treatment Plant
The Cardona Water Treatment Plant now yields 100 million liters per day (MLD) of potable treated water drawn from the Laguna Lake. The Cardona WTP employs a more rigorous and complex treatment process and types of equipment compared to other existing water treatment plants because of the diverse quality of water from Laguna Lake. The process includes treatment for suspended solids, organic matter, algae and dissolved solids. Running full capacity, the treatment plant will distribute potable water to about 800,000 population and will essentially ease the load of the central distribution system of Manila Water, which serves customers in Metro Manila.
Water Treatment Process
Raw water undergoes several treatment processes before it passes the standards for potable water. Conventional water treatment consists of the following processes: coagulation/flocculation, sedimentation, filtration and disinfection/chlorination.
Raw water coming straight from the dams carries soil, dirt, and dissolved minerals. The raw water is first treated with chlorine to get rid of any germs. Chemical polymer or “coagulants” are mixed uniformly into the water to make the dissolved minerals and dirt lump together. The lumps either float or sink. The water then passes through machines called "flocculators" that remove the dirt that floats.
The "flocs" then pass through large pools called settling basins to remove dirt that sinks. Heavy flocs will settle at the bottom of the tanks while the clarified water will be collected.
Finally, the water flows through several filter beds that act like very fine strainers, each one finer than the next, to remove microscopic impurities.
After even the smallest impurities have been removed, the water is again injected with chlorine gas to kill any microbes or germs that may contaminate the water.
Water is now safe for drinking and are then sent to distribution by gravity and by pumping.
Network and Distribution System
The East Zone network or distribution system is composed of transmission lines, distribution lines, pumping stations and reservoirs all designed to bring potable water to our customers.
Since 1997, Manila Water has laid and maintained over 5,000 kilometers of pipelines all over the East Zone. Moreover, 99 percent of currently served areas have a water supply pressure of 7 psi and above, made possible by the continuous implementation of technical solutions such as supply and pressure management. Average pressure for the entire East Zone is at 20 psi, which is significantly better than the 7 psi regulatory target.
Water Sampling and Laboratory Analysis
To ensure that the water delivered to the customers satisfies regulatory standards on quality, the Company’s Laboratory Services Department processes an average of around 900 water samples from the distribution network per month. The samples are collected on a regular basis from strategically located sampling points all over the East Zone. This number of sampling points surpasses the regulatory requirement and all results of the sampling have been consistently 100% compliant with the Philippine National Standards for Drinking Water (PNSDW), five percent above the requirement.
Samples are then tested in the Company's ISO/IEC 17025:2005 accredited laboratory against more than 50 physical, chemical and bacteriological parameters. The Laboratory Services also carries the ISO 9001, ISO 14001 and OHSAS 18001 certifications, as well as recognition by the Philippine Department of Health (DOH) and the Department of Environment and Natural Resources (DENR).
Manila Water reports, on a monthly basis, the water quality testing results to the Drinking Water Quality Committees of Metro Manila and Rizal, which in turn, publish the results in major broadsheets in the area. This way, customers are assured that they are getting the best quality drinking water from their taps.
Manila Water customers may also bring a sample of their water to the laboratory for testing.
Wastewater is a general term that includes all "used water" discharged by households, commercial and industrial establishments.
Aside from providing clean and potable water to more than 6.8 million customers in the concession area, Manila Water also provides sewerage and sanitation services to help improve the conditions of the water environment in the metropolis and safeguard public health.
Manila Water’s steadfast commitment to protect the environment is evident in the magnitude and scale of the company’s efforts to ensure that domestic wastewater from households does not contribute to the pollution of rivers and other water bodies. The proper disposal and treatment of wastewater are essential elements of Manila Water’s services. In the coming years, wastewater management will play an even more crucial role, as the company extends its wastewater services to cover more areas and benefit more people in the East Zone.
Sewerage services include the operation and maintenance of networks of sewer pipelines that collect and convey sewage to a Sewage Treatment Plant (STP) which then clean the wastewater before safely returning it to our water bodies.
In many respects, wastewater services present even greater challenges than supplying clean, safe tap water. Centralized sewer network systems for a densely populated area like Metro Manila entail huge capital investments and land requirements.
As an innovative solution to address the sewage and sanitation needs of its service area, Manila Water devised a strategy to construct compact or "package" sewage treatment plants to serve specific areas or communities where feasible. Manila Water also utilizes the Combined Sewer-Drainage System in the collection of wastewater from households. This strategy will utilize the existing municipal drainage system for wastewater conveyance, thereby minimizing the laying of separate sewer lines.
Sewage coming out from households is waste produced by humans which typically contains washing water from sinks, toilets and bathrooms, laundry waste, and other liquid or semi-liquid wastes. These are collected via a network of sewer pipelines that direct sewage flows to an STP. To date, over 300 kilometers of sewer lines are maintained in the East Zone. Manila Water currently operates a total of 38 STPs with a combined treatment capacity of 310 million liters per day.
Treated wastewater from the STPs meets "Class C" effluent regulations and is safe for discharge to creeks and rivers or recycled for non-contact purposes like toilet flushing, cleaning and irrigation. The STPs operate in compliance with existing regulatory standards of the Department of Environment and Natural Resources (DENR) and the Laguna Lake Development Authority (LLDA). Treated wastewater help revive the rivers where they are discharged because of their suitability to support aquatic life.
Wastewater Treatment Process
Manila Water’s wastewater treatment plants employ various technologies to treat wastes and pollution. Through a variety of mechanisms and processes, these treatment plants produce treated wastewater safe enough for re-use or discharge to receiving bodies of water.
Wastewater passes through the mechanical screens to remove sand, grit and debris. Raw sewage is then lifted by pumps into the head of the treatment process.
Flow rate is controlled to prevent huge variations in volume, concentration and temperature.
Large sediments are allowed to settle to separate clarified water. Wastewater then flows into tanks equipped with aerators and blowers.
The blowers supply oxygen to the tank to sustain the bacteria responsible for decomposition of pollutants.
Biological "flocs" are allowed to settle to separate clarified water.
Harmful microorganisms are removed by the addition of sodium hypochlorite. Treated wastewater, or effluent, then flows by gravity to the nearest water body.
Majority or 85 percent of households in the East Zone are not yet covered by a sewer system and instead utilize their own septic tanks. Wastewater that accumulates inside septic tanks are called septage. Septic tanks, if properly maintained, only provide primary wastewater treatment. Because septic tanks provide only partial treatment, they eventually leak out pollution into the groundwater or into municipal drainage systems, eventually finding its way into our rivers and water bodies.
To address this, Manila Water offers sanitation services called septic tank desludging. Sanitation services include the operation and maintenance of desludging vacuum tankers that clean or siphon household septic tanks, and Septage Treatment Plants (SpTPs) that receive and treat the hauled septage before disposing the treated byproducts through environmentally safe means. Manila Water currently operates two SpTPs, capable of treating a total of 1,400 cubic meters of septage daily.
Manila Water operates a fleet of vacuum trucks that perform regular scheduled septic tank cleaning services or desludging for communities at no added charge. This sanitation program is carried out in coordination with barangay officials to ensure efficient desludging service to Manila Water customers. Each household is recommended to undergo desludging every five years to prevent healthy and environmental hazards.