Module 3: Exploring the options 17 April 2017 Module 3: Exploring the options SWITCH Training Kit Module 3A: Sustainable options for water supply An overview

The issues facing urban water supply 17 April 2017 The issues facing urban water supply Increasing demand for water Deteriorating infrastructure Water supply in urban environments is coming under increasing pressure. Some of the issues are: Increasing demand for water – Increasing urban populations, economic growth and more water intensive behaviour has accelerated the demand for water in many cities throughout the world. This puts pressure on existing supplies and can lead to water scarcity. Changing weather patterns due to climate change – The impact of climate change is uncertain but on the whole it is predicted that drier weather conditions will increase the risk of prolonged drought reducing the availability of an already scarce resource in urban areas. Deteriorating infrastructure – Ageing and poorly maintained water supply pipelines result in higher levels of leakage from the distribution network. This increases treatment and pumping costs and wastes the resource. Energy costs – Water supply is reliant on energy for treatment and pumping. Variations in fuel costs therefore have implications on the cost of supplying water. Changing weather patterns due to climate change Energy costs

Links between urban water supply and other areas of the water sector 17 April 2017 Links between urban water supply and other areas of the water sector Water treatment Stormwater management There are many links between water supply and other sectors of urban water management. These include: Links with stormwater management – When collected, stormwater can be used for non-potable water supply such as irrigation of parks and gardens, and industrial use. Stormwater is also a source of aquifer replenishment and can be stored and used to supplement conventional sources of water supply. Stormwater is also a potential pollutant of public water supply sources such as aquifers and lakes. Links with water treatment – The amount of water that needs to be abstracted and treated depends on the demand for potable water and the level of leakage from the distribution system. Links with wastewater management – The volume of water supplied and used is closely related to the amount of wastewater that is produced. The reuse of greywater and treated wastewater can also supplement a city’s water demand needs, particularly non-potable uses such as parkland irrigation and industrial use. Links with water quality – The health of natural water bodies is impacted by the volume of water that is abstracted for water supply purposes. Over-abstraction from rivers leads to low flows resulting in too little water for aquatic ecosystems and less dilution of pollutants. Conversely, the pollution of resources such as aquifers, rivers and reservoirs increases the cost of treatment and can result in the reduction of use and even the abandonment of a supply source. Examples include algal outbreaks in reservoirs and the pollution of aquifers through oil spills. Wastewater management Water quality

Links between water supply and other sectors of urban management 17 April 2017 Links between water supply and other sectors of urban management Energy Housing Waste management Parks, gardens and recreation Water supply is indirectly linked with a number of urban sectors including: Parks, gardens and recreation – Land uses such as parks and gardens, golf courses and sports fields rely on large quantities of fresh water for irrigation. Housing – The construction of new housing developments creates additional water demand and the need for new distribution infrastructure Energy – Water availability from reservoirs may be restricted due to conflicting interests from hydro-power generation. Water treatment and pumping costs are also dependent on a reliable supply of energy. Waste management – Poorly managed urban waste can cause the pollution of ground and surface water sources. Local economic development – Many industries rely on a large supply of fresh water for production, washing and cooling purposes. Industrial growth therefore depends on a reliable source of supply. Health – A reliable water supply of sufficient quality and quantity is essential for the health of a city’s population. Local economic development Health

The conventional approach 17 April 2017 The conventional approach Increased abstractions from rivers and aquifers The construction of storage reservoirs The transfer of water from areas with a surplus The use of energy and chemicals for water treatment Traditionally increasing urban water demand has been met through the development of new resources. Conventional solutions typically include: Increased abstractions from rivers and aquifers – Additional boreholes sunk into aquifers and enlarged river abstraction infrastructure to increase the volumetric output from the source. The construction of storage reservoirs – The damning of rivers or the construction of riverbank storage to capture and store surplus river flows. The transfer of water from areas with a surplus – Transferring water through pipelines or canals from an area with surplus supplies The use of energy and chemicals for water treatment – Removing pollutants from raw water using technological treatment techniques that are heavily reliant on energy and chemicals.

Drawbacks of the conventional approach to urban water supply 17 April 2017 Drawbacks of the conventional approach to urban water supply Unsustainable use of local resources Cost Carbon emissions Wasteful use of resources Non-flexible The conventional approach of meeting increased water demand is through investment in new supply sources and infrastructure. As the options to develop new resources are reduced and the sustainability of using existing ones are questioned, the limitations of this approach are increasingly exposed. These limitations include: Unsustainable use of local resources – The need to meet increasing demands can cause over-abstraction from local resources. This leads to depleted groundwater levels and low river flows which have consequences for future supplies and downstream users, as well as causing damage to aquatic ecosystems. Cost – The cost of constructing, operating and maintaining new water supply infrastructure is high. Carbon emissions – Increasing water supplies typically requires an increase in water treatment and pumping. This raises carbon emissions from the water sector at a time when many cities are trying to reduce their carbon footprint. Wasteful use of resources – By investing in additional or expanded sources of supply to meet growing demand, wasteful practices such as leakage from the distribution system are not addressed. Non-flexible – Most water supply options are selected based on predicted future water demands and existing rainfall patterns. Solutions are often restricted to design specifications regarding pumping and storage capacities, and the resource that has historically been available. These cannot easily be adapted if demand forecasts prove to be too low or two high, or if climate change alters weather patterns.

A more sustainable approach 17 April 2017 A more sustainable approach Using natural systems for pre-treatment of raw water Reducing urban water demand Using alternative, non-conventional sources of supply By utilising natural treatment processes and focusing on more efficient use of available resources, treatment costs can be reduced and urban water demand met thereby mitigating the effects of water scarcity. Alternative solutions to the development of new sources of supply are based on: Using natural systems for pre-treatment of raw water – Pre-treatment of a water source using natural systems such as river bank and riverbed soils and vegetation The reduction of urban water demand – Water demand management options aim to make the most efficient use of the available resource by reducing wasteful and unnecessary usage, such as leakage from water supply pipelines, inefficient water appliances and careless behaviour The use of alternative, non-conventional sources of supply – Replacing the use of potable water for non-potable needs with water from alternative sources such as rainwater harvesting, greywater reuse and effluent recycling.

A more sustainable approach 17 April 2017 A more sustainable approach Options include: Riverbank filtration Reduction in system losses Metering and tariffs Domestic water efficiency measures Rainwater harvesting Greywater reuse Public education Water demand management and reuse options are wide ranging and can be based on improving efficiency in the treatment and distribution operations, reducing residential and non-residential water use, and substituting potable water use with, for example, rainwater, or greywater. River Bank Filtration (RBF): RBF is a process for (pre-) treating polluted surface water, often for the purpose of potable use. Surface water is abstracted through intake wells dug in the river’s banks. Organic matter and turbidity is removed as the water is drawn downwards through the sediment in the river bank and bed. RBF is a low cost and robust technology that is successfully used in Europe and North America. Reduction in systems losses – Leakage can account for the wastage of a large proportion of treated water that is pumped into a city’s distribution network. Measures such as leak detection and repair, water mains replacement and pressure reduction in the network can reduce the amount of treated water that is lost from the system. Metering and tariffs – Customers who receive their water on an unmetered fixed charge do not get billed for the amount consumed. They are therefore more likely to use water carelessly. Universal metering allows customers to be charged for what they use and is therefore a financial incentive to save water. Metering also allows tariff structures to be applied that can vary charges based on the amount of water used, household income and the season. Domestic water efficiency measures – Various measures exist to reduce household water use. Low flush toilets, low flow taps and showers, and water efficient washing machines and dishwashers are widely available at competitive prices. Low flush toilets provide particular scope for savings as toilet use typically accounts for more than a quarter of domestic water use. Financial incentives can be used to encourage customers to purchase and install efficient water using equipment. Rainwater harvesting – Potable water supply from the distribution network can be replaced for certain non-potable uses, such as garden watering, toilet flushing and cleaning, by rainwater harvested from roof surfaces. Rainwater harvesting systems can range from a simple water butt to gather water for the garden, to a more complex system where the collected rainwater is pumped into households for toilet flushing and cleaning purposes. Greywater reuse – Greywater (wastewater from domestic processes such as dish washing, bathing, laundry, etc.) can be reused for non-potable purposes such as toilet flushing and irrigation of gardens, parks and golf courses. Public education – Education and awareness raising campaigns reduce water consumption by encouraging consumers to change their water use behaviour. Highlighting the economic and environmental benefits of efficient water use can persuade people to think of water as a commodity, like electricity or gas, that should not be used wastefully.

Benefits of water demand management solutions 17 April 2017 Benefits of water demand management solutions Reduced treatment and pumping costs Reduced abstractions from the environment Reduced infrastructure investment costs Reduced water shortages Reduced carbon emissions Reduced runoff Reduced interruptions to water supply Reduced volumes of wastewater Reduced treatment and pumping costs – Reducing water consumption and losses from the distribution system results in less water to abstract, treat and distribute. This saves in chemical and energy costs. Reduced abstractions from the environment – Reduced demand results in less water needing to be abstracted from the environment. This helps to maintain healthy aquatic ecosystems and prevents over-abstraction from resources. Reduced infrastructure investment costs – Demand management measures can replace or delay the need for more costly supply-side infrastructure. Reduced water shortages – Demand management reduces reliability on sources such as reservoirs and aquifers. These can therefore be managed more efficiently and are better able to cope in times of drought reducing water use restrictions on households, businesses and industry. Reduced carbon emissions – The reduction in energy use for treatment and pumping reduces carbon emissions from the water sector. Reduced runoff – Collecting rainwater and stormwater for reuse reduces urban runoff relieving pressure on drainage systems. Reduced interruptions to water supply – Reduced leaks from the water distribution network lessens the risk of interruptions to supply. Reduced volumes of wastewater – Lowering demand and the reusing greywater reduces the amount of wastewater to be treated.

Why a non-conventional approach is more sustainable 17 April 2017 Why a non-conventional approach is more sustainable Social sustainability Economic sustainability Environmental sustainability Improved water supply reliability Reduced water bills Reduced abstraction, treatment and pumping costs Reduced infrastructure costs Less water abstracted Reduced carbon emissions Environmental sustainability: Less water abstracted to meet demand means more available for the needs of natural ecosystems A reduction in the amount of water needed to be abstracted, treated and distributed reduces energy usage and carbon emissions from the water sector Social sustainability: Fixing leaks in the system improves water supply reliability Consumers who pay for water based on what they use can reduce their water bills by changing wasteful habits Economic sustainability: Reducing water consumption saves money on water abstraction, treatment and distribution costs Water demand management solutions don’t require the construction of large scale infrastructure projects Coping with an uncertain future: Greater resilience (e.g. to climate change and uncertain future water demands) – Through greater ability to cope with uncertain weather patterns and unknown future water demands

More sustainable solutions 17 April 2017 More sustainable solutions Water butt – Rainwater collected from the roof for garden use and car washing Leakage reduction – Detection and repair of burst pipes Low flush toilet – Installation of low and dual flush toilets Water education – Targeting water use behaviour Spray tap – Reduced water usage in taps Riverbank filtration (Seoul, Korea) – Pre-treatment of raw water using soils and vegetation in the banks and beds of rivers

17 April 2017 Acknowledgements This presentation has been produced as part of the SWITCH Training Kit by: Ralph Philip and Barbara Anton ICLEI – Local Government’s for Sustainability based on the joint efforts of the following SWITCH partners: C. Muñoz-Trochez (WEDC Loughborough University), S. Kayaga (WEDC Loughborough University), S.K. Sharma (UNESCO-IHE), I. Smout (WEDC Loughborough University), A. Turner (University of Technology Sydney), S. White (University of Technology Sydney), S.K. Maeng (UNESCO-IHE), M.O. Rivett (University of Birmingham), D. Rousseau (UNESCO-IHE), S.K. Sharma (UNESCO-IHE) The UNESCO-IHE led SWITCH project runs from Feb. 2006 to Jan. 2011 and is part-financed by Directorate General Research of the European Commission under the Sixth Framework Programme. For more information see www.switchurbanwater.eu