Summary Reader Response Draft 4
The webpage "Rainwater Harvesting 101" from
Innovating Water Solutions LLC introduces what is rainwater
harvesting is. 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,
the reality is that many countries are adopting this method because it has 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 roofs 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 is a better option to
replacing imported water in the future than rainwater harvesting in Singapore.
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.), and 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 will make more contribution towards replacing
imported water in the future in Singapore.
Rainwater harvesting in Singapore has
progressed significantly since 2011. The water catchment area in Singapore has
expanded from half of Singapore to two-thirds of Singapore 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.
However, despite the contributions
that rainwater harvesting can make towards 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 the 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. Singapore is a small
country; hence this expansion will limit the area 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 PUB (Public
Utilities Board) 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 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 both have their 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 more
significant 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
Hong, J. (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. Channel News
Asia.
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/
ST Engineering. (n.d.) News - Tuas
Power-ST engineering consortium opens Singapore’s fifth desalination plant.
Public Utilities Board. (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
HSL Constructor
Pte Ltd. (n.d.) Tuas desalination plant 3.
https://hsl.com.sg/projects/tuas-desalination-plant-3/
Water Technology. (2015, August 27) Tuaspring desalination and
integrated power plant.
https://www.water-technology.net/projects/tuaspring-desalination-and
integrated-power-plant/
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