Rainwater harvesting seems nothing to many Filipinos. However, those who advocate its practice say it could address the shortage of water supply now haunting millions of people in this Southeast Asian archipelago.

Dr. Jessica Calfoforo Salas, Ph.D., president of the International Rainwater Catchment Systems Association, is calling on every Filipino “to resort to the time-tested ancient wisdom” of harvesting the rain “to avert the water crisis we are faced with.”

She points out that with the growing need to conserve the country’s groundwater resources, rainwater harvesting “is the next best option to meet our water needs.” She pitched: “Rainwater is for free, so why not make use of it?”

Dr. Johannes Paul, Ph.D. of the German Development Service that is popularizing environment-friendly technologies in the Philippines like rainwater harvesting echoes Salas’s view. He said that collecting the rain that falls on the roof or a sealed surface is a “simple concept that brings a lot of benefits.”

“Rainwater-harvesting is very affordable. Everybody is capable of using the technology. We just need to re-popularize it among the Filipino people,” Paul said of the once very popular technology edged out from the lives of the Filipinos by “modern technologies.”

Former president Fidel Ramos, who led the Philippine delegation to the Third World Water Forum last March, also pitched for the institutionalization of rainwater harvesting upon his return from the forum. He said, “Rainwater harvesting in both urban and rural areas must now become a mandated public policy, as well as a nationwide, community-based, bayanihan [community volunteerism] system to insure long-term water supply.”

Advantages of Rainwater Harvesting

Paul adds that it also regulates drainage and river input; reduces soil erosion and transfer; provides additional water for public use and emergency response; reduces flood risk on roads and sealed surfaces; improves liquid waste management; and improves river management.

In his paper titled, Rainwater: Wasted or Utilized, Paul notes that rainwater harvesting “promotes self-sufficiency and gives appreciation of this essential and precious resource since it is harvested independently of any central system.”

He wrote, “Collecting rainwater is not only water conserving. It is also energy conserving since the operation of a centralized water supply requires high energy input for pumping and distribution. A decentralized rainwater supply can use gravity flow if designed the proper way.

“Rainwater harvesting also lessens local erosion and flooding caused by drainage from constructions, road development, land use changes, area sealing, etc. The rain is instead captured and stored and only gradually released at a later time. Thus storm-water run off, the normal consequence of rainfall, becomes captured rainfall and is available for a number of productive uses.”

Paul also noted that the purity of rainwater makes it also an attractive water source for certain industries that need pure water. “Rainwater, before hitting a building or the earth surface, is one of the purest sources of water. However, rainwater harvesting needs to consider and treat eventual microbiological and chemical components, which may be dissolved and collected from the catchment areas.”

It may also be an alternative source of water supply, particularly in areas where water is scarce or in places where water supply services are not adequate, Salas added.

She also said that in rain-drenched areas, rainwater catchment systems could be used for different purposes like flood mitigation, sewerage management or compensating for the lack of water in sealed surfaces. In addition, in areas with modern system connection of pipes to houses and building, rainwater could be used as a substitute for processed potable water for non-drinking purposes such as flushing the toilet, cleaning the garage, watering plants, laundry and other purposes.

Untapped Resource

Despite these advantages, Salas laments that rainwater has become an “untapped resource” due to the introduction of piped-in water systems around the archipelago. “Filipinos have easily gotten accustomed to faucets causing the popularity of rainwater harvesting to decline,” she explains.

Paul says that if someone studies the actual water supply situation or the local rainwater management in the Philippines, “it becomes obvious that rainfall is mostly not seen as a water resource but often regarded as a hindrance for construction and operation. Sealed areas, roofs of buildings and roads are provided with collection systems for the run off, but the latter is regarded as useless and only drained into the next river.”

One problem Paul sees is the absence of a regulatory system to manage rainwater. Sadly, “this puts rainwater to waste. Being a valuable fresh water resource before hitting the catchment area, rainfall becomes a waste when discharged into the drainage system.”

Salas agreed. She wrote in her paper titled Why Rainwater Harvesting? that in the Philippines, the use of rainwater tanks has been associated with government programs for water supply and sanitation.

“The government considers rainwater collection as one of the low technology alternatives for water supply and it is classified as a Level 1 technology. The government and the public prefer a system of water services delivery that reaches the consumers at their homes in potable processed form, available 24 hours a day and is called Level 3 technology. Water usually comes from a river reservoir or from an underground natural supply, processed in a treatment plant and delivered through a system of pipes and controls.

“Water supply for Level 1 and 2 has been relegated to the local government units who themselves are egging to access the Level 3 technology. Since aspirations are placed on the improved system, decisions are directed towards its achievement. Technology improvements for rainwater catching as well as for its other uses were not in the priority concerns of both the national agencies and the local government. They lagged behind.

“The lopsided view that gave bias to technology, operation, financing, and dissemination of systems has left 77 percent of the country’s population fetching water several meters, sometimes kilometers, from a source outside their homes and sometimes of doubtful quality. If translated to number of persons, the figure accounts for 56 million Filipinos or 9.3 million households.”

Philippine Water Situation

Based on the number of water right permits granted by the National Water Resources Board (NWRB), the government agency tasked to look after the country’s water resources including its use and protection, there is an increasing trend in groundwater and surface water usage in the Philippines.

From 129,777.75 million cubic meters in 1990, this went up to 144,622.50 million cubic meters in 1995 or an 11.4 percent increase over a period of five years.

In terms of intake uses by sector, the agricultural sector was still the largest user at 89.7 percent on the average (1990-1995), while domestic use registered an average of 6.6 percent, with the remaining 3.7 percent attributed to industrial use.

These figures, experts say, have since changed minimally.

Re-popularizing the Indigenous Technology

Rainwater harvesting   Source: New Mexico Water Conservation Program

click for enlarge

Salas says she remains optimistic that Filipinos will “re-appreciate” the culture of rainwater harvesting. “It has been part of our forebears’ lives. I think we shall appreciate its practice if we remember how our great-grandparents valued rainwater. If they practiced it for centuries, why can’t we?”

Paul on the other hand emphasized that the re-integration of rainwater harvesting also means the incorporation of a national policy. “If local government units have no strict framework to follow, they’d be at a loss. A national policy is needed by the local governments.”

If the government succeeds in re-popularizing the technology, Paul says it would save as much as 43.5 billion pesos (P1=US$55) annually besides its environmental benefits.

“Assuming an average daily water demand of 100 liters per capita everyday, the Philippines must provide 2.9 billion cubic meters of freshwater every year for the domestic sector alone. This water is mostly extracted from groundwater reservoirs. The cost equivalent would be approximately 87 billion pesos a year based on the water price of 30 pesos per 1,000 liters.

“Consequently, a substitution rate of the public water supply with 50 percent rainwater would not only be very advantageous considering economic effects but could help secure surface and groundwater resources and options for further development.”

Interestingly, more than 150 Filipinos and foreign nationals, who gathered in this central Philippine city for the Second National Rainwater Utilization Conference last 2-6 December, agree with Salas and Paul.

In the manifesto they signed, they all say that the reintroduction and mainstreaming of rainwater harvesting at both local and national levels through ordinances and a national law could very potently address the country’s growing water needs.