BREEAM Wat 03 Water Leak Detection, Prevention & Specification

Published 25 Sep 2016

Water Leak Detection - BREEAM Wat 03 Compliant Leak Detection


  • By Chris Dodds : estimated reading time 8 minutes

Thorne & Derrick have supported the M&E building services industry since 1985 and today provide expert technical support, system design and supply for water leak detection systems compliant with BREEAM Wat 03.

Whether your building is classed as new construction, in-use or refit and refurbishment we can provide BREEAM Wat 03 recommendations.

BREEAM Wat 03 regulation reduces the impact of water leaks that may otherwise go undetected and guides building development towards achieving BREEAM compliance by adopting the following notes.

We will overview the BREEAM requirements to secure 2 Credits for sustainable property development by specifying and installing a BREEAM compliant Water Leak Detection system to achieve Wat 03.

We will then provide sample specifications written by Thorne & Derrick which conform fully to achieving BREEAM Wat 03 status for Leak Detection & Prevention.

In a forthcoming Blog, we will provide guidance and specification tips on securing up to 5 BREEAM credits by installing water efficient fittings including thermostatic mixing valves manufactured by HORNE.

The 2 available BREEAM Credits are categorised into major leaks and minor leaks:

  1. Major Water Leaks: BREEAM credit achieved by installation of an accredited leak detection system capable of detecting major water leaks on the mains water supply within the building and between the building and the utilities water meter (water leak detection).
  2. Minor Water Leaks: BREEAM credit achieved by installation of an accredited flow control device to WC area/facilities to ensure water is supplied only when needed – the flow control device would normally be a closed shut-off solenoid valve connected to a PIR (water leak prevention).

BREEAM – Who, What & Why?

BREEAM is the worlds leading sustainability assessment method for masterplanning building and infrastructure projects. BREEAM assessment processes judge the procurement, design, construction and operation of a sustainable development for compliance against performance benchmarks targets.

Watch how BREEAM was created as a cost-effective means of bringing sustainable value to development.


BREEAM: Buildings are assessed and BREEAM Credits awarded on a scale of Pass, Good, Very Good, Excellent and Outstanding


Water Leak Detection


  1. A leak detection system which is capable of detecting a major water leak on the mains water supply within the building and between the building and the utilities water meter.
  2. The leak detection system is:
    1. Audible when activated
    2. Activated when the flow of water passing through the water meter/data logger is at a flow rate above a pre-set maximum for a pre-set period of time
    3. Able to identify different flow and therefore leakage rates, e.g. continuous, high and/or low level, over set time periods
    4. Programmable to suit the owner/occupiers’ water consumption criteria
    5. Where applicable, designed to avoid false alarms caused by normal operation of large water-consuming plant such as chillers.


  1. One of the following types of flow control device is fitted to each WC area/facility to ensure water is supplied only when needed (and therefore prevent minor water leaks):
    1. A time controller i.e. an automatic time switch device to switch off the water supply after a predetermined interval
    2. A programmed time controller i.e. an automatic time switch device to switch water on and/or off at predetermined times.
    3. A volume controller i.e. an automatic control device to turn off the water supply once the maximum preset volume is reached.
    4. A presence detector and controller i.e. an automatic device detecting occupancy or movement in an area to switch water on and turn it off when the presence is removed.
    5. A central control unit i.e. a dedicated computer-based control unit for an overall managed water control system, utilising some or all of the types of control elements listed above.

BREEAM Wat 03 Compliance Notes


Mains Supply Shut-off

See criteria 1 & 2

There is no requirement for the water leak detection system to shut off the water supply when the alarm is triggered (constant water supply may still be required for certain systems/operations).


Leakage Rates

See criterion 2

This issue does not specify what the high and low level leakage rates should be however the leak detection equipment installed must have the flexibility to distinguish between different flow rates to enable it to be programmed to suit the building type and owner/occupier’s usage patterns.


System Criteria

See criterion 2

It is anticipated that the leak detection credit will usually be achieved by installing a system which detects higher than normal flow rates at meters and/or sub-meters. It does not necessarily require a system that directly detects water leakage along part or the whole length of the water supply system.


Water Utilities Meters

See criterion 3

Where there is a water utilities meter at the site/building boundary, it may be necessary to install a separate flow meter (or alternative measurement system) just after the utility meter to detect leaks; however, if the water utility company agrees to some form of leak detection being installed on their meter, this would also be acceptable.


Flow Control Systems

See criterion 3

Flow control systems may control combined WC areas, such as male and female toilets within a core, they are not required for each individual sanitary appliance. The criteria are set to encourage the isolation of the water supply to each WC block when it is not being used.


Single WCs

See criterion 3

The flow control criteria for this issue do apply to facilities which have only a single WC (potentially within smaller or low occupancy buildings). In these instances shut-off could be provided via the same switch that controls the lighting (whether proximity detection or a manual switch).


Ancillary & Multiple Buildings/UnitsThe criteria apply to the water supply to all buildings falling within the scope of the assessment.


No Water Supply To Building/Unit

See criteria 1, 2 & 3

These credits are still assessed where there are no installed fittings and therefore no water supply to the building. In these instances the facilities likely to be used by the future occupants of the assessed building must meet the criteria e.g. those facilities within the nearest accessible building.


Extensions To Existing Buildings

See criteria 1, 2 & 3

If the water supply to the new extension is via the existing building then the water supply to the existing building must be assessed against the criteria of this issue.


Shell OnlyWhere the installation of facilities within tenanted units/areas will be the responsibility of the future tenant, compliance with the flow control credit within this BREEAM issue can be demonstrated via one of the following means for shell only buildings/areas:

  1. Option 1 – Use of a tenancy lease agreement between the developer and tenant/s (full value of available credits)
  2. Option 2 – A Green Building Guide for tenant fit outs (half the value of the available credits)
  3. Option 3 – Developer/Tenant collaboration (full value of available credits)

Refer to Appendix D – BREEAM New Construction and shell and core/speculative assessments of this Scheme Document for further description of the above options.


Multi-residential Buildings & Guest Accommodation: Flow Control Specification

See criterion 3

The BREEAM credit for the specification of flow control devices in WC areas/facilities does not apply to ensuite facilities in residential areas e.g. ensuite in individual private bedrooms and a single bathroom for a collection of individual private bedrooms in halls of residence, key worker accommodation or sheltered accommodation. The BREEAM credit and criteria are however applicable to buildings with guest bedrooms with ensuite facilities, e.g. hotel rooms, and communal WC areas/facilities, e.g. communal WC facilities in hotels/hostels and care homes.


Clinical Areas In Healthcare BuildingsThe criteria for this issue do not apply to toilet facilities in clinical areas.


Here is a sample BREEAM Wat 03 specification by Thorne & Derrick :

Specification: BREEAM WAT 02 (Water Monitoring) & BREEAM Wat 03 (Leak Detection)


To ensure water consumption can be monitored and managed and therefore encourage reductions.

To reduce the impact of water leaks that may otherwise go undetected.

Leak Detection System (One bream Credit)


Thorne & Derrick water monitoring and two zone major leak detection system comprises of two BCCB control panels linked to two pulsed turbine sensors. Each BCCB control panel shall be able to work independently from one another. It is a permanent water monitoring and major leak detection system which covers all mains supplies both in and outside the building. To secure BREEAM Wat 03 the system shall provide;

  • An audible alarm and alarm output to the BMS (if BMS is available) when activated
  • Activated when the flow of water passes through the meter at a flow rate above a pre-set minimum for a pre-set period of time
  • Able to identify different flow and therefore leakage rates
  • Programmable to suit the owner/ occupier water consumption requirements.
  • Linked to a solenoid valve that shuts off the supply when the alarm is activated (if required)
  • Be able to avoid false alarms

The first pulsed water meter should be installed just after the utilities water meter and will monitor the flow rate of the mains water pipe feeding the building.

The second pulsed water meter should be installed just after the main stop valve where the supply enters the building and will monitor for leaks/water consumption within the building.

Both pulsed water meters shall be selected based on pipe diameters and / or flow rates.

An optional BMS interface allows pulses from the water meter to be registered at both the control unit, and the BMS (if required, contact Thorne & Derrick for further advice).

Water-consuming plant or building areas, consuming 10% or more of the building’s total water demand, should be fitted with easily accessible sub-meters or have water monitoring equipment integral to the plant or area (contact Thorne & Derrick for further advice).

Each water meter for BREEAM Wat 02 & BREEAM Wat 03 shall be manufactured by Elster Water using volumetric or Woltmann design, demonstrates EC approval according to the new Measuring Instruments Directive (MID) 2014/32/EU, shall be WRAS approved.

Flow Control Devices (One BREEAM Credit)

Credit and criteria is applicable to commercial areas / properties only. Thorne & Derrick flow control devices, regulate the supply of water to each WC area or facility according to demand and therefore minimise water leaks and wastage from sanitary fittings. The system shall include;

  • Installation of a sanitary supply shut off system to each toilet area within the building, controlling supply to all urinals, wash hand basins and WCs linked to a PIR movement detector such that once the washroom has been unoccupied for pre-set (but adjustable) time, the system will automatically turn the water supply ‘off’ again, thus saving water if the water systems leak, or are deliberately left on.
  • The unit shall incorporate a mains powered control unit operating a magnetic latch solenoid valve with programmable delay period of 10 seconds to 40 minutes.
  • Where combined toilet areas (for example male and female facilities) are fed from a common supply, one solenoid valve serving the core shall be installed, operating under the control of a sensor within each individual toilet area.
  • The solenoid valve shall be of a type that is normally closed, powered open.
  • Solenoid valves shall be specified to pipe diameter and / or flow rates and must be manufactured by Sirai Valves, product range L182 brass bodied, 230v, rated up to 10 bar, (minimum pressure differential required to operate: ½”, ¾” and 1” require 0.35 bar), WRAS approved product.

To discuss your requirements for BREEAM Wat 03 including Thorne & Derrick water monitoring and major leak detection systems please contact us.



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