New technologies are offering innovative ways for cities to ensure there is an adequate supply of safe, clean water
Water sustainability is a growing challenge for cities worldwide. Factors such as climate change, population growth and urbanisation are putting cities’ water supplies under strain.
Already, estimates from UNESCO suggest that 663 million people lack ready access to improved* sources of drinking water, while the number of people without reliable access to water safe for human consumption is at least 1.8 billion.
New technologies are offering innovative ways for cities to ensure there is an adequate supply of safe, clean water.
Tapping new water sources to manage drought
The City of Cape Town in South Africa has been internationally recognised for its Water Conservation and Demand Management [WCWDM] Programme, a strategy which aims to minimise water wastage, better balance available water resources, and postpone the need for expensive capital infrastructure projects. However, the urgency of the schedule has been intensified by the fact that the region is currently experiencing a drought which the Mayor declared an official disaster in March.
An internal taskforce has been set up to tackle the issue, supported by an external advisory board.
Councillor Xanthea Limberg, Mayoral Committee Member for Informal Settlements, Water and Waste Services & Energy, Cape Town, comments, “We need to ensure that we dramatically shift how the city thinks of and consumes water, especially given the current rainfall patterns and the unpredictability of weather forecasts. We have to become a far more adaptable and resilient city.”
The city has implemented measures to manage water usage such as Level 4B restrictions, increased tariffs and the roll-out of water management devices which can restrict residents’ water supply to a certain level.
However, the situation is so severe, Cape Town also needs to look at how it can access additional water. One measure is to tap into previously unused water sources by drilling boreholes into the local Table Mountain Group aquifer, and connecting them to the reticulation system. An aquifer is a body of permeable rock which can contain or transmit groundwater. A pilot project will now be undertaken which will inform larger-scale use of this resource.
Cape Town is also looking at setting up desalination plants and possibly water reclamation plants to diversify its water mix on a large scale. Pilot projects for these options are also being implemented as a matter of urgency, and are being designed in such a way that they can be scaled up quickly, if necessary.
“We are constantly engaging to understand what other alternatives are available to the city that we can incorporate into our water supply plan,” says Limberg.
The city recently put out a city-wide request for new ideas, for example, and the water department also has a new technologies unit, specifically in place to look out for new innovations and assess their relevance for Cape Town’s needs.
Cleaning water closer to home
A lack of local drinking water sources has been a long-term challenge in the City of San Diego – now, advanced technology and improved public support are changing this.
Historically, San Diego has relied on importing between 80 and 90 per cent of its water supply from the Colorado River and Northern California Bay Delta. The cost of this imported water has tripled in the last 15 years and continues to rise.
“With limited local control over our water supply, the City of San Diego is more vulnerable to droughts, climate change and natural disasters,” explains J. Brent Eidson, External Affairs, Deputy Director, Public Utilities, City of San Diego.
Pure Water San Diego is the City’s phased, multi-year program which aims to provide one-third of San Diego’s water supply locally by 2035. Recycled water is taken from the North City Reclamation Plant and treated through a series of high-tech processes: Membrane filtration, reverse osmosis and UV disinfection with advanced oxidation. For regulatory reasons the purified water is then detained in an ‘environmental buffer’ (the Miramar Reservoir) as per regulations, before being blended into the drinking water system.
The first phase of the implementation will be completed in 2021, and by then the city expects to provide 30 million gallons of purified water per day -- which is between 15-18 per cent of the city’s water supply.
Although new technologies are helping to solve city challenges, they have to be rigorously tested first, says Eidson. He explains, “State and federal regulators aren’t as nimble as we can be at the local level. So when we’re evaluating technology, what we need to make sure is that it’s going to meet the regulatory requirements of those agencies. In the case of the Pure Water plant, for example, we had a demonstration plant to show that the new technology meets the requirements of our regulators.”
New materials lower costs
In many cases the challenge is being able to implement new technologies in a cost-effective way. Scientists at the Indian Institute of Technology-Madras (IIT-M), led by Professor T. Pradeep, are developing new materials which lower the cost of water purification. The ability to deploy these on a wide scale could have a significant impact on public health issues.
For example, the World Bank suggests that 65 million people in Asia alone are facing health risks due to arsenic contamination of their drinking water. Long-term exposure can lead to chronic arsenic poisoning. Skin lesions, cancer, high blood pressure and reproductive disorders are among the effects.
Professor Pradeep and his team have developed an arsenic filter using nano-filtration technology –based on new types of absorbents which can be produced affordably and without electricity. The filtration device has been successfully tested in West Bengal and the Indian government has approved the technology.
Professor Pradeep comments, “The technology could provide a family with clean, arsenic-free drinking water for a year for the equivalent of around £2 per year.”
Beyond India it is also being trialled in South Africa, Australia, Argentina, and Bangladesh, although has not been commercially rolled out there yet.
Pradeep is now also researching other advanced water technologies such as a scalable system for reducing the concentration of fluoride in water, a way to collect and use dew, cheaper water quality sensors, and desalination processes which don’t remove all the minerals from water.
Real-time insights drive results
In addition to finding news sources of water and cleansing it effectively, Internet of Things (IoT) technology is increasingly helping businesses and residents get more actionable insights into their water usage. It is also enabling cities, businesses and utilities to better share infrastructure and data in order to reduce duplicated spending and track trends.
In the city of Charlotte in the US, 61 commercial buildings were able to reduce their energy consumption by 19% over five years, which equated to $26 million in energy bill savings. This was achieved through an initiative run by Envision Charlotte, a public-private ‘plus’ collaboration (with the plus being the utility company and the university), and involved interventions such as tenant outreach and education, as well as access to real-time granular data on energy usage.
Emily Yates, Deputy Director of Envision Charlotte, commented: “Having that granular data provided more of a real-time status, and empowered the building operators to make adjustments to reduce energy consumption – and many of these were actually low-cost and no-cost actions such as adjusting thermostats and turning lights off at night. We are now hoping to have the same results with drastic water consumption reduction.”
In partnership with technology company Itron and Charlotte Water, Envision Charlotte is running a pilot network of smart water meters in 18 of its uptown commercial buildings. The buildings share a dashboard but the data is anonymised. It allows building owners to analyse their water usage compared to the other buildings annually and monthly, as well as see a more detailed daily water consumption chart. This highlights areas where they could be doing more to manage water efficiently and also quickly flags any unusual data which could suggest a leak or similar issue in the building.
Yates said: “Leveraging utilities and having them at the table for conversations has been extremely valuable for the work that we’ve been doing. It takes a cross-sector, collaborative approach to be successful in smart cities.”
While water pressures are widespread, the specific issues vary from place to place. The challenge for cities is to choose the right technology and partner mix to enable them to respond in a manner that is timely, cost-effective, compliant and scalable.
* An ‘improved water source’ is defined as one where human use is kept separate from use by animals and faecal contamination. However, water from an ‘improved source’ is not necessarily free of bacteria or other contamination and is not necessarily safe (Source UNESCO)
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