The importance of groundwater

If you live near Parañaque, Pasig or Valenzuela, and use a pump to draw water from the ground, chances are you’ve had days when the water tasted a bit salty. Worse, you may have even seen small particles down the bottom of the glass when you’ve finished drinking. These things happen due to the adversely affected groundwater flow pattern in these areas resulting from excessive withdrawal of groundwater from the aquifer.

Unsafe water is a daily risk in many parts of the country, inclu-ding Metro Manila, and the prob-lem is going worse every year as the government is hard put in maintaining safeguards for a growing population and tackling contributory problems like pollu-tion. But the crisis of unsafe water could be reduced if the public is more aware of the problem and can take part in finding a solution.

A United Nations report states that groundwater resources worldwide are overexploited and are fast diminishing, as there is also very slow renewability. This overexploitation is happening in many countries in Asia, Middle East, southern and northern Africa, some countries in Europe and Cuba.

"The potential risks are high if the aquifers are not replenished naturally or by human interven-tion. It becomes only a matter of time before these resources run out or become economically inac-cessible," the report that was presented at the 2006 World Water Day celebration in Mexico City said.

Effects of over-extraction

The quality of what you drink has a direct link on what happens under the ground. The taste of water becomes salty because of seawater intrusion in our aquifer. With hundreds of thousands of people in Metro Manila indis-criminately extracting water from deep wells, our aquifer is in dan-ger not only of saline intrusion, but also of drying up.

National Water Resources Board (NWRB) Executive Director Ramon Alikpala said the status of Metro Manila aquifer is critical as Metro Manila is below sea level. "There is already salt water intrusion in the western part of Metro Manila because of over-extraction and the lack of re-charging of the aquifer," Alikpala said, adding that non-reple-nishment of aquifers is causing land subsidence or land sinking that can bring about flooding in the long term.

NWRB, with the secretary of DENR sitting as chairman of its board, is responsible for policy-making and management of all water-related activities.

According to an NWRB study on the status of Metro Manila’s aquifer, the worst may happen within 10 years, not necessarily simultaneously: pumping cost will be higher due to lowered water levels; increased salinity because of salt water intrusion; the government will be faced with the enormous task of flushing out intruding saline water back to Manila Bay, as it will take years of sufficient volume of freshwater to force back (to sea) the saline water that has intruded the aquifer.

The study said the present amount of groundwater with-drawn through legally registered (with the NWRB) wells is 12,823.53 liters/second, but the amount withdrawn by illegal wells plus the amount drawn by permittees (legal wells) exceeding their granted amount, is estimated by NWRB consultants (based on available data) to be 60 percent more than the total groundwater extraction of registered wells.

To address this, the water board has ruled that drilling of new wells will be allowed only in critical areas where there are no MWSS water supply connections or are not served by any water utilities. "Permits will be issued with validity period until such time that commercial surface water supply will be available in the area," Alikpala said as he stressed that drilling of new wells will be strictly prohibited in areas where the water supply is available.

How an aquifer works

What can be done to ensure that the aquifer is protected and sustained?

First, a few basic facts. An aquifer is an underground water reservoir. It is a water-saturated geologic (earth, gravel or porous stone) formation zone under-ground that stores and transmits usable quantity of water.

Underground water is one of our most valuable resources. Man extracts water from the aquifer by digging a well until the top layer of the aquifer is reached. Over-extraction or pumping too much water draws down the water table and eventually causes a well to generate less and less water.

In aquifers, almost no bacteria can live. Many pollutants are filtered out as the water passes through the soil and rocks on the way to the aquifer.

The water table is not flat as its name implies; it has crests and valleys that follow the outline of the land above it. It represents the upper surface of the groundwater. During dry spells, where a lot of water is pumped from an aquifer, the water table sinks lower.

Lands covered with trees and swamps are the usual recharge areas that refill aquifers as they readily absorb water from the rain. When these recharge areas are laid over with cemented roads, there is less water that reaches the aquifers. Moreover, oil and road dirt eventually seep down to the ground, that may lead to the contamination of the aquifer over the long run.

Only one percent of the earth’s water surface is fresh water; the rest is saline or seawater. Fresh water flows through rivers, lakes and underground streams, many of which are already polluted. That’s why aquifers and springs, which are natural sources of clean water, are very important.

It takes many years to bring back freshwater into an aquifer that has been contaminated by seawater. All efforts then must be taken to prevent aquifers from drying up or being contaminated. Our aquifers are the only sources of drinking water we can rely on in cases of drought and other calamities.

Regardless of our economic status, each one of us has a role to preserve the cleanliness of our water supply, particularly in Metro Manila. Conserving water in our own households will go a long way in ensuring the continuous supply of water in our faucets.

Leaving spaces open for plants to grow and for the soil to enrich itself also help recharge aquifers. Indiscriminate dumping of garbage will not only affect one’s health, but will also ultimately lead to water shortage if aquifers become contaminated with leachate coming from the garbage. Let’s do our share now to preserve our precious aquifers.

Over-extraction of groundwater is already posing a threat to our aquifer, our natural reservoir of water beneath the ground.