New Construction / NOR / 2016 /

05 - Water

Information correct as of 11thApril 2021. Please see for the latest compliance information.

Alternative calculation method - KBCN0547

Where it is not possible to use the standard approach to determine the building’s total water consumption, the assessment can be completed on an elemental basis. This applies even in cases where the Wat 01 Excel calculator tool has a section for a broader building type, but the defined activity areas do not match the specific project under assessment. For example, although Wat 01 calculator includes a retail calculator, bars and restaurants should be assessed using the alternative calculation method, as no relevant data is available for the specific activity within retail. Where the activity areas of the building under assessment do not allow using the relevant building type’s calculator, then the alternative calculation approach should be used.

Alternative method performance levels and credits - KBCN1007

Specifying water component performance levels according to the levels of the alternative calculation method does not equate directly to the number of credits achieved. For example, choosing all components with a level 3 performance will not equate to the achievement of 3 credits.

Applicability of flow control devices - KBCN00057

The criteria are applicable to the cold water supply only and include cold taps, WCs and urinals. Any solution implemented to achieve compliance with this Issue should effectively mitigate the risk of hot-water scalding in showers, in the event that the cold water supply is shut off.
06/03/18 - Wording amended to make the guidance more outcome-driven and to account for solutions other than not providing flow-control devices on the supply pipework to shower areas.

Areas consuming less than 10% of the building’s total water demand - KBCN0662

Where water-consuming plants or building areas are required to be sub-metered as a minimum, the requirements apply even if those plant/elements consume less than 10% of the building's total water demand.

Commercial dishwasher appropriate data - KBCN0687

If the component is present in the building but the appropriate data is unavailable from the manufacturer's product information i.e. uses a different unit of measurement, then the baseline performance level for the specified component should be used in the WAT 01 calculator. BRE Global is unable to provide a calculation method to convert data in to the correct unit for the WAT 01 calculator tool.

Domestic hot water supplied by a circulation loop - KBCN1017

Where a circulation loop is used on the domestic hot water supply, it is acceptable to only sub-meter the cold water supply. Sub-metering such systems may be impractical and the occupant can use the cold water meter readings as a proxy for overall water usage in relevant areas.

Fire hydrants and sprinklers - KBCN0680

To meet BREEAM compliance, emergency systems such as fire hydrants and sprinklers need also to be covered by a leak detection system. The leak detection system must cover all mains water supply between and within the building and the ‘site boundary'.

Flow control devices for multiple blocks - KBCN1186

The criteria are set to encourage isolation of the water supply to each WC block when it is not being used. If a single flow control device, for example one programmed time controller, is adequate to switch the water on at predetermined times that suit the usage patterns of more than one WC blocks or facilities, this can be used to demonstrate compliance. Please note that if only one timed controller is used for a large area/number of facilities, the assessor must justify that this is appropriate to the usage patterns within the building and confirm that multiple timers would be redundant (i.e. they would all be set to the same time).  Consideration should be given of any facilities that may be open longer than others, requiring these timers to be programmed differently in different areas. As long as the aim of the credit (‘to reduce the impact of water leaks that may otherwise go undetected’) can be achieved through the specification of an appropriate number of flow control devices, the credit may still be achieved if timers cover more than one WC area/facility to prevent minor water leaks.

Flow control devices on rainwater supply for toilets - KBCN0868

Flow control devices will be required on water supplied from rainwater and serving the toilet facilities. Rainwater tanks are topped up by mains water and leaks could reduce levels of stored water and hence increase the use of mains water. The leak detection requirements apply to all relevant water systems, regardless of the water source.

Flow control on cold water supply - KBCN0417

A shut-off on the cold water supply to the whole WC facility provides a simple and effective way of reducing potential water loss. Taps which contain built in shut-off valves will not prevent any water leaks from the supply to the tap and so do not fulfil this intent. The intent of the flow control criteria is to prevent minor water leaks occurring within the pipework of WC facilities.

Flow rate for ‘click’ taps - KBCN0543

The flow rate for click taps should be taken as the maximum flow rate, as quoted by the manufacturer, of the lower range before the water break or 'click'. All water consumption is based on 'typical' use patterns and it is assumed that most operations of 'click' taps will be at the lower level.

Flow rate for a mixture of taps - KBCN0173

Whichever is the higher of the 'average flow rate' or the 'proportionate flow rate' should be used within the Wat 01 Calculator.  

Flow restrictors - KBCN0976

If a flow restrictor can be demonstrated to effectively reduce the flow of water and it is integral to the fitting or supply pipework (ie not easily removed by the building occupant), this can be accounted for in calculations for this Issue. Such devices must be fit-for-purpose. Proprietary flow restrictors, therefore partly-closed isolation valves, for example, are not an acceptable solution.

Leak detection – extent of responsibility - KBCN0688

For the credit to be awarded, all the pipework in a development that the owner/occupier has responsibility for must meet the leak detection criteria.  In situations where third party organisations place restrictions on the pipework that can be metered, the scope of works (and hence placement of a meter for the use of leak detection) will start immediately after this point.  For instance where the utility company's meter is placed midway between the boundary and the building, the scope of leak detection for BREEAM purposes will be between utility meter and the building, not to the boundary (as stated in the guidance). The scope of the BREEAM criteria is only on pipework that the owner/occupier has control over.

Leak detection – inseparable building and site boundary - KBCN0388

Where there is no distinction between the site boundary and the building; the utility meter being either located on the boundary or within the building, the leak detection criteria apply to the mains water supply within the building only. The BREEAM criteria apply to the pipework that the owner/occupier has responsibility for.  

Leak detection – recycled water use - KBCN0433

The leak detection requirements still apply to all relevant water systems where water recycling systems are specified for WCs and urinals. Recycled water should be considered as a valuable resource as it replaces potable water use and, in many instances, recycling systems will still incorporate a mains-water back up.    

Leak detection – using a BMS - KBCN0439

A BMS can be used for leak detection purposes if it can be demonstrated that its integrated or add-on features meet all the requirements for a leak detection system.

Leak detection between building and utilities meter - KBCN1116

For all pipework which is the responsibility of the building owner or occupier leak detection is required between the building and the utilities water meter. This requirement is applicable regardless of the length of the pipework. Where it can be demonstrated that it is not physically possible for a meter to be installed on the pipework, the requirement for leak detection between the building and the utilities meter can be considered not applicable, and the credit awarded based on the leak detection within the building.

Leak detection system notification - KBCN0245

So long as the compliant system alerts the appropriate person to the leak so they are able to respond immediately, the assessor can judge if the aim of the issue is being met by a reliable, robust and fail-safe means of notification.    

Majority of water demand from rainwater harvesting - KBCN0860

If the majority of water use is supplied by sources other than mains or private water, for example rainwater harvesting, and this use will be monitored, additional metering of the smaller water demand that is masked by the larger demand is not necessary.

Manual watering - KBCN0553

Where the design team can justify that manual watering provides a reduction in unregulated water consumption, this can be considered as an acceptable method for reducing unregulated water use.

Measuring the flow rate of domestic components - KBCN0641

On site testing can be carried out by an appropriate professional to determine the flow rate and capacity of domestic components. This must be overseen by the client’s facilities manager and as-built drawings must be provided to confirm the presence and location of the components and any flow restrictors. Note that the conditions under which the testing is completed must be recorded, e.g. the pressure and the temperature of the water for taps. The assessor could conduct the test provided they are able to carry it out accurately.
15/02/2021: amended to cover all component types.

Metering recycled water - KBCN0658

Water-consuming plant or building areas consuming 10% or more of the building’s total water demand need to be sub-metered. This applies to recycled water, such as rainwater, grey water or process water as well as mains water. The aim of the Issue is to encourage reductions in water consumption, which is beneficial, regardless of its source. Monitoring the use of recycled water, may also help to reinforce the benefits of doing so and encourage further reductions.

Other buildings specified fittings worse than baseline - KBCN00021

Where the performance of a sanitary fitting is worse than the baseline level, the baseline level as specified in the manual should be input as the level of performance in the Other Buildings calculator tab of the Wat 01 tool.  

Process water to offset potable water demand - KBCN0586

Process water resulting from the building under assessment, can be considered for off-setting potable water demand from components that would otherwise be supplied using potable water, when in line with the criteria requirements for greywater systems. Process water resulting from the building under assessment can be considered as a form of greywater for the purposes of off-setting potable water demand.

Self-contained dwellings or units with individual utility meters - KBCN0199

Where self-contained dwellings or units covered by the assessment have their own individual energy supply and utility meter (e.g. water, gas or electricity), this supply can be excluded from the scope of the issue. All shared energy supplies and common areas under the responsibility of building management are still included in the assessment. For example, if self-contained flats in an assisted living development have individual gas supplies with their own utility meter, this supply will be excluded from the assessment. However, the lighting and small power comes from a shared distribution board on each floor, in which case this shared supply will need to be sub-metered in accordance with the criteria.
12/09/2018 Applicable to Water Monitoring Issue where appropriate
27/09/2017 The word 'units' added to include a wider range of scenarios falling under this principle.

Specialist assisted baths in care homes - KBCN0228

Specialist assisted baths in care homes or similar specialist applications can be excluded from the assessment of this issue. Due to the specific access and care needs of users, it may not be possible to reduce the volume of specialist assisted baths.  

Temporary irrigation systems - KBCN0147

Temporary watering arrangements set up purely to allow plant species or a green roof to establish are acceptable for plants relying on natural precipitation during all seasons of the year. Where this is the case, the ecologist's report must confirm the plant species and the expected time for recommended plant species to establish themselves i.e. time period for temporary watering arrangements.

Urinals – calculation of litres/bowl/hour - KBCN1010

A flushing frequency of two flushes per hour is used in the Wat 01 tool and should be applied when calculating the volume of water dispensed by urinals and compared against the water efficient consumption levels by component type for the Wat 01 issue. This method should be applied to calculate litres/bowl/hour. For example, a 13.5 L cistern feeding 3 bowls which is flushed 2 times per hour: (13.5 L / 3 bowls) x 2 times an hour = 9 litres/bowl/h.  

Using borehole water to offset water consumption - KBCN00094

Borehole water is included within our definition of "potable water" and cannot therefore be used to offset water consumption in the same way as rain or grey water harvesting. A significant amount of water used for public consumption is already drawn from aquifers and often private boreholes draw from the same aquifer that water companies use.   

Washer dryers - KBCN0699

Where a washer dryer is specified, the water consumption figure for the wash and dry cycle should be used. The drying cycle of a washer dryer is taken into account because it usually uses water during this drying process (e.g. for cooling during the drying cycle) and in some cases, this water usage can be significant.

Water consumption calculation for push and automatic shut-off taps - KBCN00052

The water consumption of push and automatic shut-off taps can be calculated for input into the Wat 01 calculator using the following steps: Step 1: Calculate the water consumption per person per use. If a tap runs for less than 20 seconds per activation, assume it will be activated twice per person for the timed duration. For example, for a tap with a flow rate of 9 litres/min and a 15 second usage duration, the water consumed per person would be: 9 x 15/60 x 2 = 4.5 litres/min. If a tap runs for 20 seconds or more per activation, assume one activation per person for the timed duration. For example, for a tap with a flow rate of 9 litres/min and a 20 second usage duration, the water consumed per person would be: 9 x 20/60 x 1 = 3 litres/min. Step 2: Multiply the water consumption figure per person by 1.5 and enter this figure into the calculator tool. Multiplying by 1.5 adjusts the consumption figure to compensate for the typical non times tap use of 40 seconds that has already been taken into account in the tool. Taking the first example above, if we multiply 4.5 litres/min by 1.5 we get 6.75 litres/min. When this is used in the tool as the flow rate specification, the consumption is 4.57 litres/person/day which more closely reflects the true level of water consumption for the push tap.  

Water consumption calculation for sensor taps - KBCN0180

The water flow rate of sensor taps can be entered directly into the flow rate cells of the Wat 01 tool. The amount of water dispensed by sensor taps for each use is determined by occupant demand in the same way as normal taps. Therefore, the default frequency of use will be applied in the Wat 01 tool and no adjustment calculation is needed for sensor taps.

Water fittings specification evidence at design stage - KBCN0420

For a design stage assessment, it is acceptable to provide data based on reasonable assumptions if the final specification of fittings is not yet available.

Water fittings used for a process related function - KBCN0418

Water fittings used for a process related function, e.g. low level ablution taps, laboratory / classroom taps, scrub-up taps, cleaners' sinks etc., should be excluded from the assessment of regulated water consumption. Only kitchen taps and those used for general hygiene washing are to be included in the assessment of regulated water consumption.
04/08/17 Added low level ablution taps (typically used for religious purposes) to exemptions.

Water monitoring when only part of a building is under assessment - KBCN0548

When only part of the building is under assessment, there are two cases for achieving compliance with the requirement to specify a water meter on the mains water supply of the building: If the whole building is under the same tenancy or ownership and management, then a meter monitoring the entire building is acceptable. However, if the floors subject to assessment are separately tenanted, then a meter at the point of entry to the assessed areas is required. Assessed areas have to be monitored separately for water consumption when only part of the building falls within the scope of assessment and where the assessed areas are separately tenanted.
Information correct as of 11thApril 2021. Please see for the latest compliance information.