It is stated in General Comment No. 15 on articles 11 and 12 of the International Covenant on Economic, Social, and Cultural Rights that “Water is a limited natural resource and a public good fundamental for life and health. The human right to water is indispensable for leading a life in human dignity. It is a prerequisite for the realization of other human rights.” (United Nations, 2003). This statement boldly articulates the value of water to human life and it is no exaggeration. As a resource, it is clear that water is one that has become almost synonymous to life itself. Humans use water for a multitude of reasons, and we do so in a variety of different ways. Besides the fact that we literally need water to be able to survive as human beings, water also plays a huge part in several of our agricultural, industrial, recreational, and environmental activities. Simply put, water has become undeniably interwoven into our society’s day-to-day operations and we, as a people, have become extremely dependent on its existence.
Practically all of the human activities that require water make use of freshwater, which is defined as water that has a low salt content and is suitable for consumption (Merriam-Webster Dictionary, 2018). Despite the fact that three-fourths of the Earth’s surface is covered with water, approximately 97.5 percent of it is known to be seawater from the oceans. These waters possess relatively high salt contents, and are thus deemed unusable for human consumption or operations. This means that freshwater – whose overall make-up is the most suitable for use in almost all human activities – is a resource that is as valuable as it is scarce, as only 2.5 percent of Earth’s water sources is considered to be suitable for potable and nonpotable uses, and only 1 percent of it actually available to human beings (Novak et. al., 2014).
Although the hydrological cycle is a continuous cycle that ensures our water sources are constantly being renewed as precipitation falls, the existing supply simply cannot compete with the growing demand for freshwater as it continues to rise with society’s growth. To put things into perspective, the following statistics may offer some insight as to exactly how much our freshwater supply dwindles with our consistent use. The Philippines is said to withdraw a total of 81.6 cubic kilometers of freshwater every year from the country’s annual average freshwater resources that equals 479.0 cubic kilometers per year (Food and Agriculture Organization of the United Nations, 2013). A more recent study conducted by the World Resources Institute (WRI) predicts that with this existing ratio between total water withdrawals and available renewable surface water, the Philippines could experience an alarmingly high degree of water shortage in the year 2040 (Luo et. al., 2015).
The staggering rates at which we deplete our freshwater sources only proves just how reliant we have become on readily available and easily accessible freshwater. Our unrelenting use of this valuable resource combined with the ever-increasing demand for more freshwater and the finiteness of its available sources is sure to completely diminish freshwater eventually – which could have near-catastrophic economic, social, and environmental effects (Munasinghe, 2009).
Knowing the negative connotations that excessive water withdrawal can bring, it is thus imperative that alternate measures be practiced so as to effectively manage and monitor the use of existing clean water sources.
For years, people have studied the natural behavior of water in an effort to develop methods that may be implemented to conserve, collect, and manage freshwater. With the use of technology, several advancements have been made in the field of water storage and management that have helped ease the strain we put on our water sources. Arguably the oldest documented effort pursued in the name of water control is the design and application of Rainwater Harvesting Systems (RHS). Rainwater Harvesting Systems are defined as systems that collect and subsequently store water from surfaces on which rain falls (Mihelcic, et. al., 2009). As the name suggests, these systems make use of rainwater as its main source of freshwater because it is known to possess several advantageous properties that make it suitable for use in several human activities. In the first volume of his book “Rainwater Harvesting for Drylands and Beyond,” Brad Lancaster lists several distinctive characteristics of rainwater that make it suitable for everyday use.
First and foremost, Lancaster properly recognizes rainwater as the primary source of freshwater. As water progresses through the hydrological cycle, water eventually falls to the surface of the Earth as precipitation in forms of rain, hail, sleet, or snow. Precipitation is responsible for replenishing secondary sources of freshwater (e.g. lakes, rivers, and groundwater) from which most of us depend on for adequate water supply. Without rainwater, existing secondary sources of water would subsequently cease to exist and the continuity of the hydrological cycle would be completely disrupted.
Another advantageous characteristic presented by Lancaster in his book is rainwater’s inherent purity. One might think it odd to refer to rainwater as pure, since perhaps one of the biggest misconceptions regarding rainwater is that it is “dirty, polluted water,” but in actuality, it is one of the purest sources of water available to us. As water is exposed to the sun’s rays, it undergoes a typical process called evaporation. This process occurs before water takes the form of clouds and it essentially distills the water, so when it falls in the form of precipitation, it becomes a pure, uncontaminated source of freshwater.
The purity of rainwater can be expressed in a precise, scientific manner by making use of its Total Dissolved Solids (TDS) values. TDS is basically an indicator that estimates the amount of foreign substances dissolved in a water sample, usually measured in terms of milligrams of remaining sludge per liter of filtered water (mg/L) which is equivalent to a unit part per million (ppm). The International Water Association (IWA) perfectly encapsulates the purity of rainwater in an online article entitled “Rainwater – Why is it Safe?” In this article, they explain how water is more likely to have a higher TDS value if it travels along considerable distances. This is because the water would be susceptible to accumulating solids from the many pollutants it may encounter as it flows. This is exemplified in the regions of a river: the water along the upstream regions of a river is likely to have a lower TDS value than that of its water further downstream, because the water is sure to accumulate solids from foreign substances as it moves to the downstream regions of the river (International Water Association, n.d.).
Bound by this logic, it becomes clear how rainwater – with its lack of contact with minerals found in bodies of water and in the ground – can be largely considered superior to tap water from faucets or even freshwater found in the Alps. As a matter of fact, the TDS in rainwater is estimated to be around only 20 parts per million (ppm), which is significantly lower than that of city water, whose levels are known to reach levels of around 800 ppm (Pienta, 2014).
Lancaster also makes it a point to highlight how rainwater’s chemical composition positively affects both man-made and natural resources. As previously mentioned, rainwater is a resource that makes virtually no contact with pollutants or minerals like, for example, calcium or magnesium. These compounds are present in ground and surface water, and they have been known to accumulate into forming white “scale” when deposited in or on common household appliances. The accumulation of said scale impedes heat conduction, which could potentially shorten the life span of common pipes and appliances. With rainwater’s distinct lack of calcium or magnesium in solution, rainwater would be the perfect alternate source of freshwater that could shirk the disadvantages brought onto appliances and pipes by scale accumulation.
Rainwater is basically also considered a natural fertilizer that is beneficial for plant life. Lancaster states that rainwater possesses a number of elements that are important in the promotion of plant growth, like sulfur and varying forms pf nitrogen. Rain has also been known to have very low salinity levels. Waters with extremely high salt concentrations cause a lot of harm to plants, as salt build-up reduces plants’ ability to take up water and conduct photosynthesis, which would ultimately inhibit plant growth.
Economically-speaking, using rainwater as a source of freshwater is an incredibly smart move, because the fact of the matter is that rain is a source of water that is free. As Lancaster states in his book, “Rainwater comes to us free of charge. It falls from the sky and we don’t pay to pump it nor do we pay a utility company to deliver it.” (Lancaster et. al., 2013). This, combined with the several other advantageous characteristics mentioned above, makes rainwater an invaluable renewable resource that could reap a multitude of benefits, should it be harvested and managed accordingly, instead of just being brushed off as runoff and diverted into drains.
That being said, the design and application of rainwater harvesting systems can thus be considered a huge leap towards efficient water storage and management. These systems have always made use of a renewable and readily-available source of water, and they have never failed to provide a means to conserve, collect, and manage said freshwater – even since its first implementation.
Back in the ancient times most rainwater harvesting systems in arid and semi-arid regions had two purposes. The first purpose was for providing water for various domestic activities especially for drinking. The second was evaporation of the rainwater from some domestic impounding systems like pools and reservoirs, made available some kind of cool feeling which more or less improved on the micro-climate, making it cooler and more comfortable. The origin of rainwater harvesting system is not precisely known but seems to be from early civilization of the Middle East and Asia several thousand years ago (Gould and Nissen-Petersen, 1999). Rainwater harvesting is multipurpose way of supplying water, usable to consumers during crisis period and also reduces the runoff and water logging during the season of heavy rainfall. Traditional knowledge, skills, and materials can be used for this system.
Based on the main problem of the study area which is at Sangat National Highschool specific principles will be used to substantiate the problem. According to the book Brad Lancaster (Rainwater harvesting for drylands and beyond volume 1) there are eight (8) principles that anyone can use to implement a successful rainwater- harvesting strategy. These principles are as follows: begin with a long and thoughtful observation, start harvesting rain at the top of your watershed then work your way down, always plan an overflow route and manage overflow as a source, then start with small and simple strategies that harvest the rain as close as possible to where it falls, spread, slow and infiltrate the flow of water into the soil, maximize living and organic groundcover, maximize beneficial relationship and efficiency by “stacking functions”, and lastly is to continually reasses your system and improve it. These principles were adopted by two brothers from the dessert town of Tuscon, Arizona who built and integrated their rainwater harvesting system using the principles mentioned (jeffvail, 2008).
Republic Act 6716 of the Philippine Constitution is an act, approved in March of 1989, enforcing the construction of environmental structures, among which are rainwater collectors. The purpose of this act is to promote the quality of life of every Filipino through the provision of adequate water supply. (RA 6716, 1989). Since then, the government has been making significant efforts in the realization of said act. For examples, in 2017, rainwater collection systems were installed by DPWH in 17 Cagayan schools (DPWH, 2017). Rainwater collection systems were built in Nueva Vizcaya schools, as well as in Southern Leyte schools this year (DPWH, 2018). Moreover, the Department of Public Works allocated Php54.4M of the present year’s budget on infrastructure program for the sole purpose of construction of rainwater collector systems in Western Visayas (Lena, 2018).
Furthermore, there have been researches and studies made regarding rainwater harvesting. In Colegio de San Juan de Letran Calamba, a research was made to determine possible applications of the rainwater collected in a sump pit that will lower the college’s water consumption cost through a rainwater harvesting system. There were three (3) systems analyzed: a system that uses a tank containing filter media and another for the filtered rainwater, a rainwater sedimentation basin treatment system, and a system of one tank for filter media but a larger tank for the filtered rainwater. Through comparison of cost and output, it was found out the first system was the best alternative. The system uses the slow sand filtration and disinfection water treatment methods by chlorination. It was estimated to produce the highest rate of return (7.78%) and shortest payback period (12.9 years) at the same time having lowest project cost. The researchers’ suggestion as use of the filtered rainwater was for non-potable use, such as for use in comfort rooms, cleaning of facilities, and watering of plants or grounds. For this system to be implemented, a study for the design of the distribution system of the filtered rainwater must be done (Francisco et al, 2015).