Tapping Rain Water

The drainage at the back of our house is partially clogged, making the water drain slowly and causes flooding. More rains will cause the water to enter our kitchen. Since it will do a lot of work to unclog the drainage and before I finish unclogging the drainage, our kitchen will already have water, so I look for something in our house that can load water and put it to the downspout to lessen the water going to the ground. The water containers were able to hold some of the rain water and slow the flooding which gives me enough time to unclog the drainage before the water enters our kitchen.

Because of what happened, a question pop up on my mind, if all the household in the Philippines or even around the world will harvest rainwater will this also stop or at least lessen the flooding during rainy season?

If every household can create a 10 feet long, 5 feet wide and 10 feet high tank, they can already store 3,750 gallons of water. In NCR or Metro Manila alone, according to 2000 census there is 135,294 households. If all of them will store 3,750 gallons of rainwater, that will be a total 507,352,500 gallons(67,822,882.2 cubit foot) of water.

NCR Land area is 6,873,294,985.92 sq ft (638.55 sq km). Assuming that the flood in NCR has an average height of 2 feet, then the volume of water in the flood is 13,746,589,971.84 cubic feet. If you will remove the volume of rainwater the NCR's household will be able to harvest, there will be a reduction of .0098 foot in the average height of floodwater.

I'm not an expert in math or physics, or whatever expertise that you need to have to give accurate findings on reducing or stopping flood and I understand that it is purely assumption and the reduction in the height of flood is not that big, making this finding not so compelling but we cannot taken for granted the financial and environmental benefits of harvesting rainwater. It is beneficial in the sense that it can save water bill and energy that we will be using in bringing the water to our home.

There are already lots of studies made regarding rain water harvesting and the benefits of it were already proven, some of it was published in the Internet. If our government authorities show their interest, and will get involve in this kind of project that will be the time the impact on flood prevention will become big and compelling.