B5 Water

Evidence requirements – Water calculator - KBCN0668

For crit1b and crit1d, it can be assumed the equivalent modelled water consumption (110 or 100 litres per person per day) has been achieved, where the following conditions have been met:

• the specified water fittings meet the standards outlined in the 'Water fittings standards' table • waste disposal and/or water softener are not specified and • either a bath and shower or shower only are specified

In this instance, the water calculator tool does not need to be completed. However, all other evidence must be provided.

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Exemption from meeting the optional standard for a particular water fitting - KBCN1351

For some developments, it may not be possible to meet the maximum water consumption required for a particular water fitting in the optional standard for a reason out of the developers control e.g. occupants have accessibility needs that require particular water fittings. These situations are reviewed on a case by case basis. If it is felt that there is a robust reason why a water fitting cannot meet the maximum water consumption required in the optional standard, please contact [email protected] If an exemption is awarded, it may not be possible for maximum credits to be available for this issue.

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External water consumption - KBCN1296

The total water consumption should include external water consumption in the same way as it is for building regulations purposes ( i.e. assumption of 5l/p/d added to the internal water consumption calculated in the water calculator)  

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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.

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Reasoning for setting requirements for total water consumption as well as water fittings standard - KBCN0993

We have set requirements for total water consumption as well as for individual water consuming fittings to limit instances where one very high water consuming fitting is specified which requires offsetting by very low water consuming fittings which are impractical to use. The intention was to achieve a balance in water consumption between fittings and ensure all fittings are usable.

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Shower over bath and a separate shower - KBCN0774

To calculate the water use in this scenario, the flow rates of both showers need to be entered into the water calculator tool as well as the capacity of the bath.

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Shower with multiple shower heads - KBCN0855

To calculate the water use of a shower with more than one shower head, one of the following should be done:

• If all of the shower heads can be turned on at once, the flow rates should be added up.
• If the shower heads can only be used one at a time, the highest flow rate should be used

22 Feb 2024 - Applied to BIU, BREEAM NC and RFO standards

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Using water from natural underground sources to offset water consumption - KBCN00094

Water from natural underground sources (for instance aquifer water accessed via boreholes) cannot be used to offset:

• NC / RFO: potable water consumption.
• IU: utility supplied water consumption.

A significant amount of water used for public consumption is already drawn from aquifers. Private boreholes may be drawing water from the same sources as public utility companies.

27-Mar-2024 - Title and text updated to broaden definition. Scheme applicability updated.

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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.

18-Nov-2022 - Updated to apply to BREEAM In-Use Version 6

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