It Droppeth [Not] Like The Gentle Rain From Heaven.
BY DR. JAIME C. LAYA
The word is that, by today, 99 percent of households in Metro Manila's East Zone (i.e., Quezon City, San Juan, Mandaluyong, Pasig, Makati, etc.) ought to have running water on their ground floors for most of the day .
Curious about what is happening, I checked things out with Manila Water's Abelardo P. Basilio and got a quick lesson in water management. It's really complicated. Rain over the Sierra Madre does not immediately and automatically end up in our homes.
Rain falls during the rainy season on the 568 square-kilometer forested watershed of Angat Dam and on the smaller watersheds of Ipo and La Mesa Dams. Forest cover is a sponge that holds rain water that it gradually releases through springs and brooks.
Dam reservoirs store water during the rainy season when there's too much of it and releases water during the dry season, keeping faucets running whether in rainy or dry season. Without forest cover and dams, rain water rushes off as flash floods leaving nothing for the dry season.
Angat water earmarked for Metro Manila households is shared by Maynilad Water Services for Manila, North Caloocan, Malabon, Muntinlupa, Las Pinas, and other parts of the West Zone; and Manila Water ("MWC") for the East Zone.
Population and water demand have been rapidly rising since Metro Manila water distribution was privatized in 1997. Leaking water from distribution pipes was then a serious problem for both Maynilad and MWC. MWC has been able to reduce leaks in its zone from 63 percent to 12 percent, helping meet the demand gap. MWC has also initiated new projects, e.g., construction of plant in Cardona to treat Laguna de Bay water. The long-term solution, however, is to have more Angat Dams.
Anyway, as La Mesa Dam was approaching critical water levels, MWC contingency plans were activated with the agreement of the authorities and others involved, including: (a) the reopening of long-sealed deep wells; (b) fielding the 156 available water tankers; (c) sharing Maynilad's water allocation; and (d) reducing water pressure and instituting no-water hours.
Basilio explains, "We are ... managing ... [the system] ... to make sure reservoirs (28 of them) are filled up always to sustain daily supply. This involves doing and implementing revised schedule of pump and refilling operations."
It's a challenging industrial engineering problem. Some neighborhoods are in low areas while other are elevated. They differ in population size and density, and in commercial, industrial, and residential profile. Water needs therefore vary as to quantity, pressure, and time of day.
Deciding on timing and length of water interruption while aiming to equalize water pressure in all areas and maintaining each of MWC's 28 water reservoirs at appropriate levels, require continuing decisions on when and how much water to deliver and to release from each reservoir, when and at what level to operate each of 20 pump stations, and what to do when one or more reservoirs run short of water.
As the old English proverb goes, "There's many a slip 'twixt the cup and the lip."
Comments are cordially invited, addressed to firstname.lastname@example.org
LET IT RAIN We should not blame it all in the clouds, blame it on our lack of dam reservoirs