Summary Reader Response Draft 1

The webpage "Rainwater Harvesting 101" from Innovating Water Solutions LLC introduces what is rainwater harvesting. Rainwater harvesting is the collection of run-off waters from buildings and other possible surfaces for future uses. In the past, rainwater used to be collected in gutters that channel water into storage units. However,  rainwater harvesting can be as simple as collecting rainwater in a rain barrel or as complicated as a large cistern to supply an entire household in the modern times. The author believes that although the idea of rainwater harvesting conjures images of old farm cistern or thoughts of developing countries, the reality is that many countries are adopting this method because it proved to be a viable method in supplying water. The author believed that rainwater harvesting is viable in the urban setting due to the convenience of collecting runoff water from your roof and directing it to a water storage tank. Hence, rainwater can help to supply water in a household. 

In my opinion, having access to clean water is important in our daily lives to maintain our wellbeing, hence there is a need for Singapore to reduce the dependence on imported water and improve on other sources to get clean water. I believe that desalination of seawater will contribute more in replacing imported water in the future than rainwater harvesting in Singapore although rainwater harvesting does contribute significantly to replacing imported water.

Desalination is the process to make seawater into pure drinking water. One major drawback to desalination is the hefty cost to purify water. Since Singapore is relying on imported water to be the main source of freshwater supply, there is a need for Singapore to use desalination despite the major drawback of cost. Although Singapore is currently using the reverse osmosis method that uses 3.5kWh/m3, Singapore is now exploring alternative methods to reduce energy consumption (PUB, 2023). Electro-deionisation is one of the methods that has been experimented and has achieved an energy consumption of 1.65kWh/m3 in a pilot plant (PUB, 2023). The energy consumption of this method is less than half of the energy used for the reverse osmosis method. Since this method proved to be more cost effective, PUB will be validating this method in the Tuas desalination plant (PUB, 2023). PUB is currently experimenting the biomimicry method which absorbs freshwater from seawater. I believe that with PUB’s effort in searching for alternative methods to purify water, desalination technology will advance and the major flaw of cost efficiency will be compensated. Therefore, desalination will be a major contributor to replacing imported water in the future.

 

According to PUB (2023), rainwater harvesting in Singapore has progressed significantly since 2011. The water catchment area in Singapore has expanded from half to two-thirds with the expansion of Marina, Punggol and Serangoon Reservoir. According to Meteorologial Service Singapore (n.d.), the annual rainfall in Singapore has increased by an average of 67mm per decade using data from 1980-2019, hence showing the importance of rainwater harvesting. This amplifies the importance in having rainwater harvesting. With a bigger catchment area to collect the increasing rainwater, rainwater harvesting’s contribution will increase as the years go by, making significant contribution to replacing imported water.


However, with the growth of urban areas, there is limited space to expand the water catchment area. According to (Housing & Development Board, 2021),  Singapore has a big demand for housing from Singaporeans, hence HDB aims to build up to 23,000 Build-To-Order (BTO) flats per year in 2022 and 2023 to match the increase in demand. This expansion will limit the limited space that Singapore has in expanding the local catchment area, stagnating the amount of water collected from rainwater harvesting. In addition, with limitation in land expansion due to the United Nation Convention on the Law of the Sea, it is hard for rainwater harvesting to contribute more in replacing imported water in Singapore. With these limitations in rainwater harvesting, it cannot be the major contributor to replacing imported water in Singapore as compared to desalination.

 

Although desalination and rainwater harvesting has its pros and cons, desalination will be a better option to replace the reliance of imported water in the future due to these two reasons. Firstly, desalination has more consistency than rainwater harvesting. Rainwater harvesting requires rain for water to be collected while desalination requires seawater that is readily available. Lastly, it is hard to improve the local catchment area in Singapore for rainwater harvesting due to the limited land space and ability to expand land in Singapore. Desalination on the other hand only requires the installation of another plant. Despite the contribution that rainwater harvesting can bring to replacing imported water, it is not a viable option as compared to desalination in replacing imported water due to the amount of water it can produce.


 

References

Housing & Development Board. (2021, December 16). HDB To Ramp up Flat Supply by 35% Over Next 2 Years.                                                                                                                   https://www.hdb.gov.sg/about-us/news-and-publications/press-releases/16122021-HDB-to-Ramp-Up-Flat-Supply-by-35-Percent-Over-Next-Two-Years


Meteorological Service Singapore. (n.d.). Weather Singapore.                http://www.weather.gov.sg/climate-past-climate-trends/

PUB. (2022, June 1st). PUB Desalination.    https://www.pub.gov.sg/watersupply/fournationaltaps/desalinatedwater

PUB. (2023, January 25th). PUB Local Catchment Water.    https://www.pub.gov.sg/watersupply/fournationaltaps/localcatchmentwater

 

 


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