The Two Techniques for Rainwater Harvesting
A news report on April 2023 states that the weather bureau has warned about possible dry spells in the late parts of 2023 until early next year. In an interview with President Marcos, he said that they are looking into rainwater harvesting as a way to prepare for the effects of El Niño. Rainwater catchment systems are usually quite simple. This would start with the catchment area which would either be a building’s roof or slab. Sometimes, it could even be the road which would then go through gutters and pipes before reaching the reservoir. There are two ways to collect rainwater–surface runoff and groundwater recharge.
Related read: Rainwater Harvesting in Republic Cement’s Batangas Plant
Surface runoff harvesting brings water collected from a flat surface, through a conduit, then into a container. One of the most familiar methods is rooftop runoff where the rainwater trickling down from the roof is stored in catch basins like rain barrels that are placed under building downspouts.
Some shops online sell actual rain barrels but these can simply be large garbage cans or large plastic containers found at home then converted into rain barrels by simply cutting out the center of the lid and covering it with a small mesh screen for filtering out leaves and other debris then adding a spigot at the bottom of the barrel as an on and off valve. It should be noted that these rain barrels should be cleaned and flushed annually to avoid inviting in problems like dengue-carrying mosquitoes or disease-causing algae. This method is the easiest to do and is a practical way of watering rain gardens or garden beds.
Groundwater recharge harvesting collects rainwater at the ground level and is a more complex system that needs storage tanks like cisterns or reservoirs built alongside a pump, and distribution elements like good piping. In this system, the catch basin is located at the bottom of a downhill slope to capture excess rainwater. Dipping buckets could be used here but pumps are usually installed for better retrieval and distribution.
Cisterns are the most familiar of these systems and are structures made of either cement, steel, cinderblocks, or even fiberglass and are found underground or partially submerged. Depending on the type of distribution pump used, the surface groundwater directed into these cisterns can go farther than the cistern’s foundation. This type of system is mostly used for crop irrigation, water for livestock, and supplying water for household plumbing.
Though surface runoff harvesting is the most common form of irrigation, there are different ways to harvest rainwater and each one depends on how much rainfall is in one’s location, how much water is needed, and for how long it is needed.
