Human can survive a week without food. However, only two or three days without water can lead to fatality. So, water is the most precious resource on earth, but why is it the most misused, abused, and misallocated natural resource? By the numbers, one person drinks 1-2 liters of water per day, but spends 100 liters for outdoor activities like gardening, cleaning, and entertaining. In 70 percent of worldwide water use that is allocated to farming; most of these farming irrigation systems operate at only 40 percent efficiency.
There are a lot more about statistics that makes us feel a bit guilty with living our daily life; not to mention about the number of people who have to live in parts of the world where it rains only once every 10 years. Luckily, Thai people have chosen the right location on earth to live without having to fight for water; until recently that we have experienced water shortage in the Eastern Seaboard. There was a fight between local people and factories over water in Rayong two years ago. Most people are not aware that this travel destination would have water shortage. Building design and construction in this region then need to incorporate features that can contain the situation. But what is it?
Last year, one of my architecture students proposed the use of very large water tanks on the rooftop of his high-rise residential project in Rayong. He thought it could reserve enough water throughout the dry season if the water shortage occurs. However, he insisted on having a private swimming pool at the balcony of each living unit just because this is a travel destination; people go there for spa!!! Sadly enough, he refused to provide a water retention pond and more green area on site as he needed some space for outdoor parking!!! He said it is difficult to find enough water to maintain the green area; and an empty water retention pond will look really nasty!!! He also said that he has to trade a higher cost of construction due to the weight of water for his building to not having to face the water shortage. He went on talking about another benefit of the rooftop water tank in terms of solar heat protection, which is not the point here. I must say that teaching this young generation makes me learn many things about how people today perceive environmental crisis differently. I can not say that his reasoning is totally incorrect, but it is not quite right to me.
So what goes wrong with his idea? And why we should have green area or water pond in our houses. Imagine the land without our houses built on; when it rains, storm water will find its way down underneath through pervious surfaces, filling up the groundwater, and the rest will flow to natural water channels. That is the way nature works since the beginning of time. As soon as we move in to occupy the land, we replace the existing green area with the houses built with concrete. We replace natural vegetated surfaces with impervious concrete slab used for parking our cars.
There is no doubt why storm water cannot be recharged into ground water, thus causing water shortage in the long run. To make the matter worse, excess storm water which cannot seep through concrete slab will lead to a higher water runoff rate. It will fill up public sewers very quickly causing flooding right after severe thunderstorms. Here, you can imagine all the dirtiness we throw into the sewers will then overflow back on our streets, our backyards, or even our living room!! . I used to see all kinds of living creatures trying to evacuate from water-filled sewers. They are thousands of cockroaches, rats, snakes, or even DRAGONS. Of course, ecosystems also exist in the sewer!!!
Now you get an idea why impervious concrete pavement can lead to serious effect on not only flooding, but also water shortage thereafter. I once said that green buildings are not only about planting more trees in the buildings. However, covering all your open space with hardscape and not providing enough water reservoirs will be worse than you could imagine; especially if everyone else is doing the same as you do. This is why housing developers are forced by government to build retention ponds so that the complex will not discharge water to the public sewage system too quickly. Some are forced to retain its storm water for at least three hours after a thunderstorm. All this regulation is built upon a concept that new housing development should not discharge more storm water than is the empty site used to before development.
To ‘Green’ your water means much more than to ‘Clean’ your (waste) water to a maximum BOD allowance (i.e., Biochemical Oxygen Demand) as it is all about landscape design, planting, retention pond, and pervious green area where storm water can penetrate through easily. New innovative product known as ‘turf pave’ or pavement which allows water penetration will help ‘green’ our water as it could sustain load from vehicles while allowing storm water penetration. This product seems to answer all the questions related to my student’s project in Rayong. We will see this kind or products coming to the market more and more in the near future. Let’s cross our fingers if it will become widely available soon before people start to fight for a drop of water.
ผู้ช่วยศาสตราจารย์ ดร. อรรจน์ เศรษฐบุตร
Asst. Professor Dr. Atch Sreshthaputra
Faculty of Architecture, Chulalongkorn University
Chairman of Green Building Program. The Association of Siamese Architects.