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Transitioning from IWS Contact Us There is a global drive to transition networks from IWS to continuous 24x7 supply as continuous pressurised conditions have been shown to have better water quality and other social benefits For further information regarding IWS research contact The University of Sheffield Some systems have successfully transitioned to 24x7 such as B ni Abb s in Algeria3 the Perugia province in Italy4 and Phnom Penh in Cambodia5 Tools to Transition Optimise management of the distribution system including creating pressure zones or district metering areas Perform frequent water balances to identify areas for improvement Collect realistic data such as pressure demands leakage locations and rates Reduce Non Revenue Water as much as possible including active pipe replacement or relining schemes Invest in new infrastructure Reduce dynamic pressures by maintaining air relief points and operating valves pumps slowly Predict future demand and plan a suitable expansion programme for the network Achieving a permanent transition to 24x7 is not easy and can require external support such as Public Private Partnerships governmental policies and subsidies Engaging with customers as users and beneficiaries of the system is vital to ensure success Prof Vanessa Speight v speight sheffield ac uk Dr Richard Collins r p collins sheffield ac uk Dr Sally Weston sally weston sheffield ac uk For information regarding development projects contact WaterAid www wateraid org uk WaterAidUK References 1 S E Galaitsi et al 2016 Intermittent Domestic Water Supply Causal Consequential Pathways Water 8 274 2 A W Bivins et al 2017 Estimating Infection Risks and the Global Burden of Diarrheal Disease Attributable to Intermittent Water Supply Using QMRA Environmental Science and Technology 51 13 pp 7542 7551 3 P Klingel F Nestmann 2014 From Intermittent to Continuous Water Distribution A Proposed Conceptual Approach and a Case Study of B ni Abb s Algeria Urban Water Journal 11 3 pp 240 251 4 A Bettin P Malano 2017 Italy Action Plan to Face Water Crisis Moving from IWS to 24x7 In Dealing with the Complex Interrelation of Intermittent Supply and Water Losses pp 107 112 5 E S Chan 2009 Bringing Safe Water to Phnom Penh s City International Journal of Water Resources Development 25 4 pp 597 609 Intermittent Water Supply
What is Intermittent Water Supply Intermittent Water Supply IWS refers to a piped distribution system where drinking water is delivered less than 24 hours per day to customers Over a billion people worldwide across all inhabited continents receive drinking water intermittently IWS systems only supply water for shortened periods of time The duration and schedule of supply provided vastly varies between countries utilities seasons and even different sections of the same network Customers often resort to other forms of collecting water such as ground roof tanks and community taps Water utilities typically adopt IWS to control consumption and reduce water wastage during water scarcity However IWS has serious consequences that affect the physical infrastructure distribution equality and water quality which all impact community well being Three Types of IWS1 1 Predictable Water supply generally occurs within a predictable and anticipated schedule Customers can adapt so that with effective storage IWS can resemble continuous supply 3 Unreliable Customers do not know how much water will arrive or when causing economic and behavioural uncertainty 2 Irregular Periods of supply arrive at unknown intervals within short periods of every few days Consumers expect a certain volume of water but cannot anticipate when it will arrive Impacts of IWS Water Quality Water Wastage IWS substantially impacts water quality with serious public health consequences 17 million cases of infection per year are attributed to IWS worldwide2 IWS is usually implemented to reduce water losses but it can result in more water wasted than saved Customers tend to collect as much water as possible Depressurised and empty infrastructure increases the risk of contamination especially in areas with no or poor sanitation facilities Stagnation in the network and customer storage equipment encourages bacterial growth and attracts certain insects that spread disease e g mosquitoes carry malaria Chlorination levels needed to counteract contamination are harder to maintain due to the short duration of supply but over chlorination can lead to adverse health effects during supply periods perhaps extracting more water than necessarily needed Customers discard old water when new water is available Overfilling storage and open taps waste water Deteriorated infrastructure causes more opportunities for leakage Unreliable supply means that some industrial users run on tankered water IWS systems have some of the highest Non Revenue Water rates in the world Infrastructure Society Operating the distribution system intermittently impacts negatively on the infrastructure Water supply is central to many components of society therefore IWS has broader impacts Infrastructure integrity rapidly deteriorates meaning that more replacement is necessary costing time and money Air in the system during draining periods can cause excessive pressures and increase the number of pipeline bursts IWS and meter malfunctions mainly due to air reduces data collection and network efficiency More time is spent by utilities implementing intermittency e g operating valves than maintaining network infrastructure Frequent power cuts in some areas limits system automation and feedback People use their time managing their water instead of other activities such as employment and leisure Traveling to collect water particularly by women and girls increases the risk of violence Coping costs of purchasing and maintaining water storage equipment may be detrimental in low income areas IWS results in customers less willing to pay for poor quality of service IWS can cause high inequalities between communities with socio political consequences Some authorities use IWS as a means of marginalising certain groups
What is Intermittent Water Supply Intermittent Water Supply IWS refers to a piped distribution system where drinking water is delivered less than 24 hours per day to customers Over a billion people worldwide across all inhabited continents receive drinking water intermittently IWS systems only supply water for shortened periods of time The duration and schedule of supply provided vastly varies between countries utilities seasons and even different sections of the same network Customers often resort to other forms of collecting water such as ground roof tanks and community taps Water utilities typically adopt IWS to control consumption and reduce water wastage during water scarcity However IWS has serious consequences that affect the physical infrastructure distribution equality and water quality which all impact community well being Three Types of IWS1 1 Predictable Water supply generally occurs within a predictable and anticipated schedule Customers can adapt so that with effective storage IWS can resemble continuous supply 3 Unreliable Customers do not know how much water will arrive or when causing economic and behavioural uncertainty 2 Irregular Periods of supply arrive at unknown intervals within short periods of every few days Consumers expect a certain volume of water but cannot anticipate when it will arrive Impacts of IWS Water Quality Water Wastage IWS substantially impacts water quality with serious public health consequences 17 million cases of infection per year are attributed to IWS worldwide2 IWS is usually implemented to reduce water losses but it can result in more water wasted than saved Customers tend to collect as much water as possible Depressurised and empty infrastructure increases the risk of contamination especially in areas with no or poor sanitation facilities Stagnation in the network and customer storage equipment encourages bacterial growth and attracts certain insects that spread disease e g mosquitoes carry malaria Chlorination levels needed to counteract contamination are harder to maintain due to the short duration of supply but over chlorination can lead to adverse health effects during supply periods perhaps extracting more water than necessarily needed Customers discard old water when new water is available Overfilling storage and open taps waste water Deteriorated infrastructure causes more opportunities for leakage Unreliable supply means that some industrial users run on tankered water IWS systems have some of the highest Non Revenue Water rates in the world Infrastructure Society Operating the distribution system intermittently impacts negatively on the infrastructure Water supply is central to many components of society therefore IWS has broader impacts Infrastructure integrity rapidly deteriorates meaning that more replacement is necessary costing time and money Air in the system during draining periods can cause excessive pressures and increase the number of pipeline bursts IWS and meter malfunctions mainly due to air reduces data collection and network efficiency More time is spent by utilities implementing intermittency e g operating valves than maintaining network infrastructure Frequent power cuts in some areas limits system automation and feedback People use their time managing their water instead of other activities such as employment and leisure Traveling to collect water particularly by women and girls increases the risk of violence Coping costs of purchasing and maintaining water storage equipment may be detrimental in low income areas IWS results in customers less willing to pay for poor quality of service IWS can cause high inequalities between communities with socio political consequences Some authorities use IWS as a means of marginalising certain groups
What is Intermittent Water Supply Intermittent Water Supply IWS refers to a piped distribution system where drinking water is delivered less than 24 hours per day to customers Over a billion people worldwide across all inhabited continents receive drinking water intermittently IWS systems only supply water for shortened periods of time The duration and schedule of supply provided vastly varies between countries utilities seasons and even different sections of the same network Customers often resort to other forms of collecting water such as ground roof tanks and community taps Water utilities typically adopt IWS to control consumption and reduce water wastage during water scarcity However IWS has serious consequences that affect the physical infrastructure distribution equality and water quality which all impact community well being Three Types of IWS1 1 Predictable Water supply generally occurs within a predictable and anticipated schedule Customers can adapt so that with effective storage IWS can resemble continuous supply 3 Unreliable Customers do not know how much water will arrive or when causing economic and behavioural uncertainty 2 Irregular Periods of supply arrive at unknown intervals within short periods of every few days Consumers expect a certain volume of water but cannot anticipate when it will arrive Impacts of IWS Water Quality Water Wastage IWS substantially impacts water quality with serious public health consequences 17 million cases of infection per year are attributed to IWS worldwide2 IWS is usually implemented to reduce water losses but it can result in more water wasted than saved Customers tend to collect as much water as possible Depressurised and empty infrastructure increases the risk of contamination especially in areas with no or poor sanitation facilities Stagnation in the network and customer storage equipment encourages bacterial growth and attracts certain insects that spread disease e g mosquitoes carry malaria Chlorination levels needed to counteract contamination are harder to maintain due to the short duration of supply but over chlorination can lead to adverse health effects during supply periods perhaps extracting more water than necessarily needed Customers discard old water when new water is available Overfilling storage and open taps waste water Deteriorated infrastructure causes more opportunities for leakage Unreliable supply means that some industrial users run on tankered water IWS systems have some of the highest Non Revenue Water rates in the world Infrastructure Society Operating the distribution system intermittently impacts negatively on the infrastructure Water supply is central to many components of society therefore IWS has broader impacts Infrastructure integrity rapidly deteriorates meaning that more replacement is necessary costing time and money Air in the system during draining periods can cause excessive pressures and increase the number of pipeline bursts IWS and meter malfunctions mainly due to air reduces data collection and network efficiency More time is spent by utilities implementing intermittency e g operating valves than maintaining network infrastructure Frequent power cuts in some areas limits system automation and feedback People use their time managing their water instead of other activities such as employment and leisure Traveling to collect water particularly by women and girls increases the risk of violence Coping costs of purchasing and maintaining water storage equipment may be detrimental in low income areas IWS results in customers less willing to pay for poor quality of service IWS can cause high inequalities between communities with socio political consequences Some authorities use IWS as a means of marginalising certain groups
Transitioning from IWS Contact Us There is a global drive to transition networks from IWS to continuous 24x7 supply as continuous pressurised conditions have been shown to have better water quality and other social benefits For further information regarding IWS research contact The University of Sheffield Some systems have successfully transitioned to 24x7 such as B ni Abb s in Algeria3 the Perugia province in Italy4 and Phnom Penh in Cambodia5 Tools to Transition Optimise management of the distribution system including creating pressure zones or district metering areas Perform frequent water balances to identify areas for improvement Collect realistic data such as pressure demands leakage locations and rates Reduce Non Revenue Water as much as possible including active pipe replacement or relining schemes Invest in new infrastructure Reduce dynamic pressures by maintaining air relief points and operating valves pumps slowly Predict future demand and plan a suitable expansion programme for the network Achieving a permanent transition to 24x7 is not easy and can require external support such as Public Private Partnerships governmental policies and subsidies Engaging with customers as users and beneficiaries of the system is vital to ensure success Prof Vanessa Speight v speight sheffield ac uk Dr Richard Collins r p collins sheffield ac uk Dr Sally Weston sally weston sheffield ac uk For information regarding development projects contact WaterAid www wateraid org uk WaterAidUK References 1 S E Galaitsi et al 2016 Intermittent Domestic Water Supply Causal Consequential Pathways Water 8 274 2 A W Bivins et al 2017 Estimating Infection Risks and the Global Burden of Diarrheal Disease Attributable to Intermittent Water Supply Using QMRA Environmental Science and Technology 51 13 pp 7542 7551 3 P Klingel F Nestmann 2014 From Intermittent to Continuous Water Distribution A Proposed Conceptual Approach and a Case Study of B ni Abb s Algeria Urban Water Journal 11 3 pp 240 251 4 A Bettin P Malano 2017 Italy Action Plan to Face Water Crisis Moving from IWS to 24x7 In Dealing with the Complex Interrelation of Intermittent Supply and Water Losses pp 107 112 5 E S Chan 2009 Bringing Safe Water to Phnom Penh s City International Journal of Water Resources Development 25 4 pp 597 609 Intermittent Water Supply
Transitioning from IWS Contact Us There is a global drive to transition networks from IWS to continuous 24x7 supply as continuous pressurised conditions have been shown to have better water quality and other social benefits For further information regarding IWS research contact The University of Sheffield Some systems have successfully transitioned to 24x7 such as B ni Abb s in Algeria3 the Perugia province in Italy4 and Phnom Penh in Cambodia5 Tools to Transition Optimise management of the distribution system including creating pressure zones or district metering areas Perform frequent water balances to identify areas for improvement Collect realistic data such as pressure demands leakage locations and rates Reduce Non Revenue Water as much as possible including active pipe replacement or relining schemes Invest in new infrastructure Reduce dynamic pressures by maintaining air relief points and operating valves pumps slowly Predict future demand and plan a suitable expansion programme for the network Achieving a permanent transition to 24x7 is not easy and can require external support such as Public Private Partnerships governmental policies and subsidies Engaging with customers as users and beneficiaries of the system is vital to ensure success Prof Vanessa Speight v speight sheffield ac uk Dr Richard Collins r p collins sheffield ac uk Dr Sally Weston sally weston sheffield ac uk For information regarding development projects contact WaterAid www wateraid org uk WaterAidUK References 1 S E Galaitsi et al 2016 Intermittent Domestic Water Supply Causal Consequential Pathways Water 8 274 2 A W Bivins et al 2017 Estimating Infection Risks and the Global Burden of Diarrheal Disease Attributable to Intermittent Water Supply Using QMRA Environmental Science and Technology 51 13 pp 7542 7551 3 P Klingel F Nestmann 2014 From Intermittent to Continuous Water Distribution A Proposed Conceptual Approach and a Case Study of B ni Abb s Algeria Urban Water Journal 11 3 pp 240 251 4 A Bettin P Malano 2017 Italy Action Plan to Face Water Crisis Moving from IWS to 24x7 In Dealing with the Complex Interrelation of Intermittent Supply and Water Losses pp 107 112 5 E S Chan 2009 Bringing Safe Water to Phnom Penh s City International Journal of Water Resources Development 25 4 pp 597 609 Intermittent Water Supply