Summary Reader Response Draft 3
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. Currently, Singapore currently has 5 desalination plant. SingSpring
Desalination Plant produces 30 million gallons (Keppel Infrastructure Trust, n.d.),
Tuaspring Desalination Plant produces 70 million gallons (Water Technology,
2015), Tuas Desalination Plant produces 24 million gallons (Jose, 2018), Jurong
Island Desalination Plant produces 30 million gallons (ST Engineering, n.d.),
Keppel Marine East Desalination Plant produces 30 million gallons (Mohan, 2021),
totalling to 184 million gallons a day. This makes up to 43% of the daily water
consumption in Singapore which is about 430 million gallons a day. This shows
that desalination is slowly taking over the main contributor of water in
Singapore.
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 (PUB, 2023). 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. 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.
There is a flaw in
rainwater harvesting in Singapore. 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. With
these limitations in rainwater harvesting, it cannot be the major contributor
to replacing imported water in Singapore as compared to desalination despite
its contribution. There is also one major drawback to desalination which
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). The con of
desalination is not as significant as compared to the con of desalination
because of PUB’s effort in experimenting different methods. 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. Hence, desalination will be a bigger contributor to replacing
imported water in the future than rainwater harvesting despite it contributing
to replace imported water.
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, comparing the cons of both
desalination and rainwater harvesting, the cons of rainwater harvesting is
stronger than the cons of desalination. There is more difficulty in improving
the local catchment area in Singapore for rainwater harvesting due to the
limited land space and ability to expand land in Singapore as compared to
experimenting new methods for desalination. Despite the contribution that
rainwater harvesting can bring to replacing imported water, it cannot be the
biggest contributor 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
Jose, H. (2018, June 28). Singapore
opens third desalination plant in Tuas. The Straits Times.
https://www.straitstimes.com/singapore/environment/singapore-opens-third-desalination-plant-in-tuas
Keppel Infrastructure Trust.
(n.d.). SingSpring desalination plant.
https://www.kepinfratrust.com/portfolio/environmental-services/singspring-desalination-plant/
Mohan, M.
(2021, February 4). Singapore's first large-scale desalination plant
capable of treating both seawater and freshwater opens. CNA.
Maxwell-Gaines, C.
(2020, July 27). Rainwater
harvesting 101 | Your how-to collect Rainwater guide. Innovative Water
Solutions LLC.
https://www.watercache.com/education/rainwater-harvesting-101
Meteorological Service Singapore.
(n.d.). Weather Singapore.
http://www.weather.gov.sg/climate-past-climate-trends/
News - Tuas Power-ST engineering
consortium opens Singapore’s fifth desalination plant | ST engineering. (n.d.). ST Engineering.
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
Tuas desalination plant 3. (n.d.). HSL Constructor Pte Ltd.
https://hsl.com.sg/projects/tuas-desalination-plant-3/
Tuaspring
desalination and integrated power plant. (2015, August 27).
Water Technology.
https://www.water-technology.net/projects/tuaspring-desalination-and
integrated-power-plant/
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