Technical Report on Achieving Water Neutrality in the Severn Trent Region
Submitted By hsanadhya
Technical Report on achieving water neutrality in the Severn Trent region
The concept of water neutrality is a rather new but significant concept for water demand management. It is an ambitious concept which targets to make sure that there is enough water to support any development without requiring additional water resources. There are two main reasons because of which the water neutrality becomes an important concept which include the policy of government which aims at a quicker growth in housing keeping a target of over 3 million new houses by 2020. The plan to achieve this growth depends upon existing water management plans and the growth point and eco-towns. The other key factor is the availability of water resources either today or in future which can be used to meet the demand for water in the areas of England and Wales. Most of East midlands area is served by Severn Trent water which is targeting to put a check on the carbon footprint by bringing in water neutrality and improving energy efficiency.
The concept of water neutrality is a vital concept for the purpose of water resource management keeping new development in mind. It can be defined as offset of water demand in the existing community by the means of making the buildings and houses increasingly water efficient. In other words, total water demand should remain same with the new housing development in the region. Most of the studies performed on the subject of water neutrality have been based on this definition of the concept. Most importantly the study performed by the Environment Agency on feasibility of achieving water neutrality in the Thames Gateway region (Environment Agency, 2007), which is an important part of the policy of the government for housing growth targeting an improvement in the affordability of housing. The 2007 Green Paper on Housing from the government levelled out a policy which targeted to develop over three million new houses by the year 2020 with a rate of over 200,000 houses a year. The paper pointed out that this additional growth in housing would have to be planned at new growth areas and eco-towns. This increase in growth of housing projects and the limited water resources coupled with the changes in climatic conditions have led the exploration of the concept of water neutrality in great detail by also keeping in mind the broader hydrological and ecological framework and to see how best the concept of water neutrality can be utilized to maximise on existing water resource management practices (Communities and Local Government, 2007).
The primary objective of this study is to prepare a technical report for achieving water neutrality in the Severn Trent region of the United Kingdom where a local council is considering a proposal to allow a large new housing development of around 20,000 homes to be built on the outskirts of an existing rural village consisting of around 200 homes. With the given scenario, a technical report needs to be written which would:
• Advise and inform the council about necessary water supply, storage, quality, quantity, cost and facilities required to manage the new development.
• Indicate the impacts of the development on the local hydrological environment and identify the major environmental risks and/or benefits of water neutrality and suggest measure that can be taken to cope with these impacts for a more sustainable development.
The study is going to be from the hydrological as well as water neutrality delivery standpoint, working on the environmental hazards as well as benefits as well as probable delivery issues that often have greater relevance from diverse spatial skin scales as well as in different physical contexts.
Research and Technical Content
The concept of water neutrality is a policy driver which targets improvement in the efficiency of water in both the new and existing development in the region. Therefore, the focus of water neutrality must be towards minimising demand of water from new development and try to offset the new demand as much as possible by decreasing the demand in the existing development. In the present study of achieving water neutrality in the Severn Trent region, it is assumed that
• Majority of water supply to the existing and the proposed new housing development would be done through public water supplies which is treated and distributed by the water companies.
• Majority of the public water supply caters towards household demand and some of it caters to non-household demand.
The standards of water neutrality must focus on the management of demand of water in both households and non-households and should also keep in mind the other options such as industrial demand of water. While analysing the approaches for water neutrality some of the alternative approaches were also considered which could help in water resource management such as waste water treatment and management, winter storage and decentralisation of water supply, modernising the patterns of land usage which can help in increasing water surplus considering the broader catchment management scenarios. Although it would be very hard to achieve 100% level of water neutrality for the goals set for the new developments but some level of offsetting can still be achieved (Ofwat, 2007). For each development, the factors affecting water neutrality can be different in nature. The offsetting potential greatly depends upon the nature of both the existing and the new development and the hydrological conditions of the region of development, also called the environmental drivers.
The research methodology consists of the following steps:
• Scoping the concept of water neutrality in the Severn Trent region by setting out questions which can expand the concept of water neutrality beyond managing water demand, defining spatial context for water neutrality etc.
• Deriving water neutrality by setting water neutrality targets by considering environmental drivers.
• Identifying appropriate approaches for calculating water neutrality parameters such as environmental surplus, net additional water demand, potential for offsetting etc.
The potential of offset depends on the following factors:
• The ratio of the size of new development to the size of existing development within the region where water resources are located.
• The rate of per capita consumption in the existing housing which hugely depends upon how is water metered in the region and various other factors such as the population and other socio-economic factors.
• Rate of per capita consumption which is predicted for the new development, especially the CSH level being planned for the houses. Higher the level of offsetting for each development, higher is the level of water neutrality.
This particular analysis targets on environmental attributes for water neutrality, since these are likely to be of principal value if we have to achieve water neutrality goals. Essentially the most relevant indication of ecological problem in this particular framework is usually regarded as water system characterisation extracted from water Framework Directive.
Estimating the Environmental Surplus
How the flow of a water body condition can be utilized as a highly important gauge in the future course of impartial water targets, based on environmental excess at the region of the water availability stage is an important question to answer. A more detailed evaluation at this juncture should take into consideration the following:
• The excess of environmental water within a given water body which are at present used as a diversion for the development of a given area. This method will give a suggestion of the water available towards diversion without any major investments in infrastructure assets. Although this could lead to the need of transfers between zones.
• The excess of environmental water within a given water body which are at present not used as a diversion towards the development of an area. This condition will give an estimate of the water available for diversion, taking into account the diversion costs, water treatment costs and transportation expenditure for providing extra public water supplies.
This type of assessment should take into account the actual diversional situation and look closely at the availability of water during low flows on Q95. This would entail the study of the environmental surplus, taking into account, possibility of extra diversions within present licenses and also study where new licenses are required for diversions which are to be maintained continuously (Therival, R. et. al, 2008). There is every possibility, that over a period of time, the value of the environmental excess may change. These changes may occur due to the following parameters - Habitat Directive Review of Consents or drastic climate changes that are not too far to be ignored. The cumulative or the singular effects of any of these governing factors or parameters can reduce the quantity of water that may be taken from the environment.
This environmental excess factor, gives a definite indication of the steps to be followed in the later appraisal of offset potential. The demand evaluation described in section 4.2 shows that, if extra diversion is necessary, then, an alternative to counter balance the demand or other supply sources may have to be considered. In such a scenario, creating a winter shortage would be more suitable.
Estimation of the net demand for additional water - The demand Expected from new development
It is suggested that the estimation of the growing demand from the new development, should be based on the parameters of design of the different Code for Sustainable Homes efficiency levels in the assessment of neutrality in water. 20,000 new homes can be built –out in the coming decade, according to the different codes levels. Both realistic as well as unrealistic rates should be decided as a minimum level so that there could be a range of rates for build –out to help decide on the adoption of the Code for Sustainable Homes as its predictions is still prejudiced. Taking into consideration, information that is specific to that site should be done where ever it is applicable. Such information could be the condition laid down by the local planning authority ((Therival, R. et. al, 2008)).
Since household development has been usually more comprehensive than information on non-household development, there needs to be an estimation of the demands of non-household development. The non-household developments usually include Hospitals, schools, and offices and in most cases the floor space is usually provided and to gather more information it is generally published from where it can be got.
Ambiguity Related To the Pressures from New Development
An uncertainty exists in predicting the demand for water and whether its use will be in accordance with the Code for sustainable Homes or CSH. The standardized norms for the usage of water in the new homes have been set and it would be difficult to determine whether the residents of these homes will adhere to the standards of water usage. It is also very difficult to assess if the rate of consumption will be a representative of the national average rates of consumption, though it can be assumed that there is an added ambiguity at the lower end of consumption than in the population in general (UKWIR, 2007). To assist in this study the following uncertainties were assumed:
1. Half of the existing ambiguities that are present in the demands of the new household at CSH should be analogous to the estimates of the water company’s demand uncertainty
2. Three quarters of the existing ambiguities that are present in the new household demands at CSH should be at least +/- 5% above the estimates of the water company’s demand uncertainty.
3. 5/6 of the existing ambiguities that are present in the new household demands at CSH should be+/- 10% above the estimates of the water company’s demand uncertainty
Though the figures exhibit a high indication of being important for the analysis, there is a recommendation for further analysis that would be able to provide a more formidable and convincing estimation of these uncertainties.
The uncertainties should be considered as a factor to the requirements that results from the rates of the Code for Sustainable Homes build –out.
Potential for offsetting
It is hard to describe particular thresholds for these parameters. Nevertheless, as a guide the below mentioned points ought to be considered. It is probable that extra effort from Government as well as regulators will be highlighted on lessening average per capita consumption (PCC) towards the objective of 130 l/person/day. Hence, an approximation of potential PCC decrease could be resultant of calculation of the weighted average PCC in the water resource zone and subsequently subtracting the 130 l/h/d target value.
Metering is estimate to contribute to a decrease in the per capita utilization. Hence this approximation of potential PCC reduction must be revised towards downside if present meter saturation in the water resource zone is more than the national average of approximately 30% (UKWIR, 2007). An approximation of 5 l/h/d for each 10% above the 30% average has been utilized in this analysis, but added research would be needed to gain an extra strong estimate of this variable. Retrofitting water effectiveness devices into present houses will be an intricate and costly task that will need large effort and co-ordination from several stakeholders and strong stages of buy-in from people. All retrofits will not work or cannot be kept in place, and a lot of households are not appropriate or easy for installation. There is also a probability of being a higher limit on a lot of retrofits that can be executed in a specific period of time. Each of these factors will influence the increasing rate of retrofits.
A famous study known as Thames Gateway Water Neutrality study (Environment Agency 2007) that is found retrofitting in approximately 50% of present households was important for achieving neutrality. This is taken as an upper limit on what is probable to be without basic changes in our approach towards water resource management along with public approaches to water utilization. It is apparent that higher increasing rates (may be up to the 50% level) will be achievable in higher water resource zones (that is where the percentage of new to present households is low). It is also probable that the increasing limit will reach previously in lesser water resource zones, consequently limiting the offset potential.
Based on this analysis, there are 5 single value parameters which will affect offset potential. Theoretical rates for these parameters are mentioned below by the case study that has been presented before, i.e. 20,000 new houses in a water resource zone along with 100,000 present households:
• New to present ratio 20000 : 200 (i.e. very high)
• Present per capita consumption 140 (i.e. comparatively low)
• Present meter penetration 30% (i.e. akin to present national average)
• Highest retrofit 30% (i.e. medium range, comparatively optimistic rate)
• Retrofit decrease 10 l/h/d (i.e. 140–130, no metering payment)
This method used a high level approximation of retrofit decrease (i.e. 10 l/h/d in the example). This number will require being assessed for each detailed resource zone, but this figure is comparatively conservative in the perspective of the predicted savings in the available literature.
The discussion was wrapped up with the conclusion that water neutrality will in general be focused on the organization of public water supplies; also it should highlight on reducing water utilization in households as well as other buildings. Nevertheless, it may at times be suitable to take other types of water abstraction into consideration in the water neutrality calculations along with ‘quick wins’ from operational utilizations of water or outflow may at times be suitable as well (Waterwise, 2008).
Water neutrality study is carried out best at the water corporation water resource zone level, by water company data for the yearly average or else the crucial period planning circumstances that are utilized in water resources planning. The study should comprise ambiguity connected with demand management actions (WRc 222a, 2006). There will require being long-term monitoring as well as reassess of supply plus demand data to consider if water neutrality activity is being efficient at dropping demand.
It is obvious from the analysis that water neutrality requires to be measured in the perspective of the present water resource management as well as licensing system. It should not be taken as a substitute for the present regulatory tools. The 2nd task in this analysis was to describe water neutrality aims. It is known that the initial objective of the water neutrality theory is to lessen the demand for water from houses as well as other buildings in the fresh and current growth. Thus targets have to be focused on attaining this goal. Nevertheless, it is also known that some other approaches might be suitable in certain situations, as recognized in the scoping job described on top and the description of targets must also consist of these substitute methods of achieving neutrality.
For attaining a complete level of water neutrality is an ambition, and it may not be probable or suitable to set such a demanding goal for all new growth (DEFRA press release, 2007). There will be ‘drivers’ as well as ‘limitations’ that will describe what level of neutrality (amid 0% and 100%) is suitable. Drivers are more probable to include environmental aspects, political or societal will, climate alter mitigation, and cost-efficiency. Limitations are most probably to consist of the relative size of the growth, utilization rates in the current development and expected consumption in the new growth.
This report regards several methods to quantify these drivers and limitations so that the suitable neutrality objective for a new growth can be described in terms of percentage. In addition, the report sets out a wide categorization of the potential for attaining water neutrality which is based on the relative range of these drivers and limitations (Dan McCarthy, 2011). This method is considered additionally in the 3rd part of this analysis using theoretical information that describe the offset potential as well as ecological drivers that describe the most suitable approach to the water neutrality. This method could offer a screening tool to measure suitable approaches to water resources supervision for new progression.
This analysis took into account various approaches to assess water neutrality in the Severn Trent region by using the concept of drivers and constraints which help identifying the suitable approach in order to establish standards for water neutrality and various environmental drivers and water neutrality offset constraints were taken into account. A framework needs to be established which can be used to analyse the environmental surplus with the additional water demand because of new housing development.
Communities and Local Government, 2007. Homes for the Future: More Affordable, More Sustainable.
Environment Agency, 2007. Towards Water Neutrality in the Thames Gateway: Modelling Baseline, Business as Usual and Pathway Scenarios. Environment Agency Science Report SC060100/SR1.
Ofwat, 2007. Security of Supply Report 2006/07.
Therival, R., Drury, C. and Hepburn, R., 2008. Achieving Water Neutrality in the South East Region: Discussion Paper.
UKWIR, 2007. A Framework for Valuing the Options for Managing Water Demand.
Waterwise, 2008. Evidence Base for Large-Scale Water Efficiency in Homes.
WRc 222a (2006), Cost and benefits of approaches to metering, www.wrcplc.co.uk
DEFRA press release (2007), http://www.defra.gov.uk/news/2007/070426a.htm
Future Water: The Government’s Water Strategy for England, Department for Environment, Food and Rural Affairs. February, 2008, p. 31-35.
Dan McCarthy(2011), Climate Change and the UK Water Industry: Stepping up to the Challenge, Black & Veatch Water
Environment Agency (2010), Water Demand Management Bulletin, 2010