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  • Abstraction

    The removal of water from a source.

  • Abstraction licence

    Authorisation granted by the Environment Agency to allow the removal of water from a source.

  • ADD - Average day demand

    Total demand over a year divided by the number of days in a year.

  • ADO - Average deployable output

    The annual average daily deployable output of a source/treatment works or a group of sources/treatment works (the average daily DO, in million litres a day, or Ml/d, over a year).

  • ADPW - Average day demand in peak week

    One seventh of total demand in the peak week of any 12 month period (ADPW). Also known as summer peak period.

  • AH - Available headroom

    The difference between water available for use (including water imported into the supply area) and demand at any given point in time.

  • AIC - Average incremental cost

    The unit cost of the water supply or water savings of a particular option.  Calculated as the net present value of the capital and operating costs of the option, divided by the net present value of the water produced by it.

  • AISC - Average incremental social cost

    The unit cost of the water supply or savings of a particular option. Calculated as the net present value of the scheme’s financial, environmental and social costs divided by the net present value of the water produced by it.

  • AIM - Abstraction incentive mechanism

    A programme to reduce abstraction from the most environmentally sensitive abstraction sources at times of greatest water stress.

  • AMP

    A five-year asset management period. For example, AMP7 is an asset management period 7, from 2020 to 2025

  • Annual average

    The total demand for water in a year, divided by the number of days in the year.

  • AR - Annual Return

    The annual return of data submitted to the Environment Agency by all water companies in England.

  • ASR - Aquifer storage recovery

    Injection, storage and subsequent use of water held in groundwater sources.

  • Aquifer

    A body of permeable rock which can contain or transmit groundwater.

  • Baseline

    Describes the continuation of existing and already planned policies and practice, but without any new ones coming into force. Used to establish what the situation would be if no new policies or measures were adopted.

  • Baseline demand forecast

    A demand forecast which reflects our current policies around managing demand for water, and assumes the quickest achievement of current, agreed leakage targets, as well as implementation of the company’s water efficiency programme, irrespective of any surplus in water supplies.

  • Baseline supply forecast

    A forecast of the water supplies that are achievable from existing and already planned and approved sources, using existing licence limits and conditions and existing infrastructure (and any constraints of that infrastructure).          

  • Best value

    The UK Government expects water companies to provide reliable, sustainable supplies at best value to customers while protecting the environment. See Guiding Principles for Water Resources Planning (Defra, 2016).

  • Borehole

    A deep, narrow shaft made in the ground for the purpose of extracting water.

  • Business plan

    Water companies produce a business plan that covers a five-year period. This shows how we will manage our water supply service and where we will invest the money we raise from customers’ bills.  If it is a water and sewerage company, it will contain details of how that company plans to manage wastewater as well as water supplies.  This plan is used by Ofwat to set water bills for a five-year period.

  • CAMS - Catchment Abstraction Management Strategy

    The Environment Agency’s programme of assessing and classifying the abstraction status of surface water catchments and groundwater sources across England and Wales.

  • CAPEX - Capital expenditure

    Spending on capital equipment, also known as capital investment. This includes spending on new or improved machinery, equipment and buildings. Capital expenditure is not used for maintenance and repair of existing assets.

  • Carbon costs

    The calculated cost associated with the carbon generated during the construction and operation of a scheme.

  • Conjunctive use

    This phrase describes the practice of using both surface water and groundwater supplies in ways that maximise their combined outputs. For example, in wet years surface water sources would be used for storage and supply of water, while during dry years the supply from surface water sources would be supplemented with water from groundwater sources.

  • Consumer Council for Water (CCWater)

    The Consumer Council for Water is the independent representative of household and business water consumers in England and Wales.

  • Consumption

    The particular element of water demand that is used by household and non-household (commercial, industrial, retail, institutional and agricultural) users – but excluding losses of water in the distribution system and underground supply pipes.

  • COO - Change of occupancy

    Change of occupancy of a household property.

  • CCG – Customer Challenge Group

    The CCG is a key stakeholder in the development of our business plan.

  • CP - Critical period

    The time period in which the balance between supply and demand is at its most critical over the course of a year.  This may be a week, a month or a longer period up to a maximum of three months.  Our critical period is the average day peak week (ADPW: see definition), also known as summer peak week.

  • Customer metering programme (CMP)

    Our programme to meter the majority of household properties across our supply area.

  • Defra - Department for the Environment, Food and Rural Affairs

    The government department responsible for setting water policy.

  • Demand management

    The implementation of policies or measures which help control or influence the consumption or waste of water.

  • DI - distribution input

    The amount of water entering the distribution system at the point we produce it.

  • DL - distribution losses

    Made up of losses on large water mains, service reservoirs, and smaller distribution mains and communication pipes.

  • DO - deployable output

    The reliable output of an active source, or group of sources, or of a bulk supply of water, which is constrained by: environment; licence, if applicable; pumping plant and/or well/aquifer properties; raw water mains and/or aquifers; transfer and/or output main; treatment; water quality.

  • Drought order

    An authorisation granted by the Secretary of State under drought conditions, which imposes temporary restrictions upon the use of water and/or allows for abstraction/impounding of water beyond the normal licences.

  • Drought permit

    An authorisation granted by the Environment Agency under drought conditions, which allows for temporary abstraction / impounding of water beyond the normal licences.

  • DWI (Drinking Water Inspectorate)

    The government body that regulates the quality of drinking water.

  • dWRMP

    Draft water resources management plan.

  • DY - dry year

    The year in which unrestricted demand for water can only just be met by available supplies.

  • DYAA - dry year annual average

    The annual average value of water demand, deployable output or some other quantity over the course of a dry year.

  • DYCP - dry year critical period

    The time in a dry year when demand is greatest, often termed the peak week. Also commonly known as the summer peak period.

  • EA - Environment Agency

    The government-appointed environmental regulator for the water industry.

  • EBSD - economics of balancing supply & demand

    A method which economically assesses the balance of supply and demand-side options. Any imbalance between supply and demand can be met either by demand side options, such as metering, water efficiency and leakage, or by providing additional water resources – supply side options.

  • EIA - environmental impact assessment

    An assessment process which determines the likely environmental impact of a given action or intervention; and assesses how effective any mitigation measures are in reducing the impact on the environment.

  • Environmental and social costs

    Environmental and social impacts can be valued in monetary terms so that they can be added to, or subtracted from, other items with monetary value applied to them - such as capital and operating costs.  A number of techniques exist for estimating the value that society has placed on the environment.

  • European site

    European sites are those classified under Directive 2009/147/EC on the Conservation of Wild Birds (Birds Directive) or designated under Directive 92/43/EEC on the conservation of natural habitats and of wild fauna and flora (Habitats Directive).

  • Final planning demand forecast

    A demand forecast which reflects our preferred policy for managing demand for water throughout the lifetime of the water resources management plan, and after analysing all the options to balance supply and demand.

  • Final planning scenario

    The water available for use and final planning demand forecast we set out in our plan, and on which basis we provide data to our regulator Ofwat.

  • Forecast/plan horizon

    The end date of the demand forecast or our water resources management plan (in this case 2020 to 2045).

  • Preferred final plan

    The preferred final plan of our WRMP which sets out how we intend to balance the supply and demand for water at least total cost to customers, society and the environment, and having regard to the plan’s practicability, flexibility and impact.

  • fWRMP - final WRMP

    The final WRMP approved by the Secretary of State for Defra.

  • Groundwater

    The water held in voids in the rock and soil found in an underground aquifer.

  • HH - household

    A domestic property occupied by householders. These are properties used as single dwellings (normally occupied), receiving water for domestic purposes which are not factories, offices or commercial premises.

  • Household size

    Number of people living in a household.

  • HRA - Habitats Regulations Assessment

    An assessment of the potential impacts on designated sites of the measures or interventions we are proposing in our plan; it also assesses how effective any mitigation measures are in reducing the impact on designated sites.

  • INNS

    Invasive non-native species.

  • l/h/d - litres per head per day

    The average amount of water used per person each day.

  • l/prop/d - litres per property per day

    The average amount of water used per property each day.     

  • Leakage reduction

    Controlling the loss of treated water through leaks in the distribution system by actively finding and fixing leaks and/or by replacing whole sections of pipe or upgrading equipment.

  • Least cost planning

    An approach that minimises all the costs of managing the supply and demand balance for the duration of the plan (See also EBSD).

  • LoS - level of service

    The frequency with which we can impose different types of water restrictions during water shortages (and which are supported by our customers).

  • MCA – multi-criteria analysis

    The multi-stage process which we use to screen supply and demand-side options using a wide range of different criteria.

  • MCM – micro-component modelling

    The modelling process we use to predict future demand for water. This is based on understanding how water is used in homes now by people and appliances, and how this may change in the future.

  • Meter optants

    Properties in which a meter is installed at the request of its occupants.

  • mHH - measured household

    A household who has a water meter and therefore pays for water by measured volume.

  • Ml/d

    Megalitres per day (a megalitre is a million litres).

  • mNHH - measured non-household

    A non-household property who has a water meter and therefore pays for water by measured volume.

  • MRF - minimum residual flow

    A pre-defined minimum rate of water flow that must be left in a watercourse to support abstraction of water – below this level abstraction must cease. Also known as a hands-off flow.

  • NEP - National Environment Programme

    See WINEP - Water Industry National Environment Programme

  • NHH - non-households

    Properties that are not occupied as domestic premises - for example, factories, offices and commercial premises –but which receive drinking water supplies.

  • Normal year annual average daily demand

    The total demand in a year with normal or average weather patterns, divided by the number of days in the year.

  • NPC - net present cost

    The present day equivalent cost of an option or intervention in our plan. 

  • NPV - net present value

    The difference between all the benefits arising from a project and all the costs arising from the project. 

  • NY - normal year

    A year in which temperature and rainfall values are at or close to their long term average.

  • NYAA - normal year annual average

    The annual average daily value of water demand, deployable output or some other quantity over the course of a normal year.

  • Ofwat - Office of Water Services

    The independent economic regulator for the water industry. 

  • OPEX - operating expenditure

    Our day-to-day operating costs.

  • OR - occupancy rate

    The number of occupants in a household.    

  • Outage

    The temporary loss of reliable water (see deployable output) due to planned or unplanned events.  An example of planned events is where we need to carry out maintenance of our water sources; an examples of unplanned events are where there are power cuts or failures in our treatment processes. 

  • PCC - per capita consumption

    The average amount of water used by one person per day.

  • PD - peak demand

    The highest occurring demand, measured either hourly, daily, weekly, monthly or yearly over a specified period of time.

  • PDO - peak deployable output

    The average daily deployable output, measured in million litres per day (Ml/d), at the time of peak demand, whether over a period of a week (the peak week), a month (the peak month) or some longer period.

  • Peak factor

    The difference between annual average demand for water and summer peak day demand for water.

  • PPC - per property consumption

    The water used by a measured or unmeasured property over a given period (litres per property per day, l/prop/d).

  • PR - Price Review

    The five-yearly review by Ofwat of business plans which set out the services and investment water companies need to deliver, and the level of customers’ water bills for the same five-year period.  See also AMP.

  • PR19

    The 2019 price review process that determined the services and investment water companies would deliver during 2020 to 2025, and the level of customers’ water bills for the same period.

  • Problem characterisation

    A framework that guides water company’s choice of methods and decisions for its water resources management plan. The more complex the planning problem to be addressed, the more detailed the methods are.

  • Risk

    A measure of the probability and magnitude of an event and the consequences of it happening.

  • RP - return period

    The average frequency of something occurring over a period of time.

  • rWRMP - revised WRMP

    The revised WRMP produced by (some) water companies following public consultation on their draft WRMPs.

  • SAC - Special Area of Conservation

    A site designated as being of special conservation value under the European Habitats Directive.

  • SEA - Strategic Environmental Assessment

    An SEA is the process by which we demonstrate how we have incorporated environmental considerations into our policies, plans and programmes of work.

  • Security of supply

    The confidence with which we can meet our agreed levels of service (see Level of Service).   Supplies are considered secure if our resources are sufficient to meet demand for water, and allowing for an additional buffer (see target headroom).

  • SELL - Sustainable Economic Level of Leakage

    The point at which the cost of reducing leakage to save water becomes the same cost as developing new water resources to produce more water.

  • SIC - Standard Industrial Classification

    The classification system used for grouping commercial and industrial properties into similar categories.

  • SoR - Statement of Response

    The statement which water companies prepare and publish to show how they have addressed representations made on their draft water resources management plan.

  • Source

    A defined place where water is abstracted from a well, spring or borehole, or from a river or reservoir.

  • SPA - Special Protection Area

    A designated site of value for wild birds under the European Habitats Directive.

  • SR - Sustainability reduction

    The reductions in water abstraction which are required by the Environment Agency to meet statutory and/or environmental requirements.

  • Supply demand balance

    The difference between the water that is available for use and the demand for water. 

  • Tariffs

    The pricing mechanism by which a water company could charge for water at different rates – for example a higher rate in the summer and a lower rate in the winter (seasonal tariff).

  • TH - target headroom

    The buffer which we add to our demand forecast so that we have some allowance built in to our WRMP.  This covers the uncertainties that exist in our estimates of the supply demand balance when looking 25 years ahead.

  • TL - total leakage / losses

    The total sum of losses of water from distribution mains and supply pipes.

  • Total water management

    All water management activities from source to tap, this includes resource management, production management, distribution management and customer-side demand management.

  • UKCIP - United Kingdom Climate Impacts Programme

    The Government-funded body responsible for disseminating climate change and climate change impacts projections to stakeholders, including water companies.

  • UKCP09

    UK Climate Projections 2009, as published by Defra (2009)

  • UKWIR - United Kingdom Water Industry Research

    The collaborative research body of the water companies of England & Wales.

  • umHH - unmeasured household

    A household without a water meter paying for water through some other measure, such as rateable value or assessed charge.

  • umNH - unmeasured non-household

    A non-household without a water meter paying for water through some other measure such as rateable value.

  • Universal metering

    A universal (and in the context of a WRMP also compulsory) programme of installing water meters to households throughout a company’s supply area.

  • Unrestricted demand

    The level of demand for water right up to the point when water use restrictions are in place.

  • USPL - underground supply pipe losses

    Losses on the section of pipework between our distribution system and where water enters a customer’s property.

  • Void property

    An empty property connected to our distribution system but not charged for water because it has no occupants.

  • WAFU - water available for use

    The overall amount of water that is available to use. This takes account of the water we lose through planned and unplanned events (see outage) sustainability reductions (see sustainability reduction); but also water we transfer out of our supply area to other companies (exports) and water we receive from other companies (imports).

  • Water efficiency

    The initiatives that are designed to help or support customers to save water.

  • WRMP - water resources management plan

    The statutory 25 year plans that all water companies in England & Wales are required to update, publish and consult on every five years. The plans show how companies intend to secure water supplies for current and future customers, at least cost to customers, society and the environment, while meeting all other environmental obligations.

  • WRMP14

    The WRMP for the period 2015 to 2040 which was formally approved by the Secretary of State for Defra in 2014.

  • WRMP19

    The WRMP for the period 2020 to 2045 which will be consulted on before being formally approved by the Secretary of State for Defra in 2019.

  • WRP tables - water resources planning tables

    Tables used for presenting key data associated with a water resources management plan.

  • WRPG - Water Resources Planning Guideline and Guiding Principles

    The guidance document published by the Environment Agency, Ofwat, Defra and the Welsh Government to provide advice to water companies on what they should include in their WRMPs.

  • WRZ - water resource zone

    The largest possible area in which all water resources can be shared so that all customers in that area experience the same level of service.

  • Water resource zone integrity

    A formal assessment process to demonstrate that our water resource zones meet the regulatory definition of a WRZ and are therefore fit for purpose when preparing our WRMP.

  • WINEP - Water Industry National Environment Programme

    The programme of environmental measures agreed for action between Government, the Environment Agency, Natural England, Ofwat and the water companies.

  • WISER - Water Industry Strategic Environmental Requirements

    WISER provides a joint strategic steer for water companies from Environment Agency and Natural England on the environment, resilience and flood risk for business planning purposes.

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