General Guidance

Key terms The following are key terms used in this document: Note: Terms shown with * are defined in legislation, either in the Building Act 1984 or the Building Regulations 2010, where the definition may be fuller than the definition given here. BCB means Building Control Body: a local authority or an Approved Inspector. *Building means any permanent or temporary building, but not any other kind of structure or erection, and a reference to a building includes a reference to part of a building. This includes dwellings (houses, flats) and public buildings. *Building work includes the erection or extension of a building, the provision or extension of a controlled service or fitting in or in connection with a building, and the material alteration of a building, or a controlled service or  fitting. Combined temperature and pressure relief valve means a mechanically operated valve that opens to discharge water when a fixed (factory set) temperature or fixed (factory set) pressure is exceeded. Controlled service or fitting includes a service or fitting subject to Schedule 1 requirements in respect of sanitation, hot water safety, water efficiency, drainage and waste disposal, combustion appliances and fuel storage, conservation of fuel or power, and electrical safety. Direct heating means a method of heating in which the heat source is integral with the hot water vessel. Examples are an electrical immersion heater, or a gas burner with a flue arrangement that passes through the vessel so that the flue transfers heat to the stored water, or the circulation of water from a vessel situated  near a burner with a flue arrangement so that the flue transfers heat to the circulating water. Domestic hot water means water that has been heated for cooking, food preparation, personal washing or cleaning purposes. The term is used irrespective of the type of building in which the hot water system is installed. *Earth-closet means a closet having a movable receptacle for the reception of faecal matter  and its deodorisation by the use of earth, ashes or chemicals, or by other methods. This will therefore include chemical and composting  toilets. Exempt buildings and work means the erection of any building or extension of a kind described in regulation 9 of and Schedule 2 to the Building Regulations 2010; or the carrying out of  any work to or in connection with such a building or extension, if after the carrying out of that work it is still a building or extension of a kind described in that Schedule. Expansion vessel means a vessel to temporarily accommodate the expansion of water from the unvented hot water storage vessel as it is heated. Greywater is domestic wastewater excluding faecal matter and urine. When appropriately treated this may replace the use of wholesome water in WCs, urinals, irrigation or washing machines. Harvested rainwater means rainwater harvested from roofs or other suitable surfaces and collected and stored. When appropriately treated, this may replace the use of wholesome water in WCs, urinals, irrigation or washing machines. Heated wholesome water means water that, when cold, was wholesome in accordance with the definition below and has been subjected to a heat source to increase its temperature. Hot water storage system means a vessel for storing:

  • heated wholesome hot water or softened wholesome hot water for subsequent use
  • water that is used to heat other water
together with any ancillary safety devices described in paragraphs 3.10 and 3.11 of this Approved Document and all other applicable operating devices. Hot water storage system package means a hot water storage system having the safety devices described in 3.10 and 3.17 of this Approved Document factory-fitted by  the manufacturer, together with a kit containing other applicable devices supplied by the manufacturer to be fitted by the installer. Hot water storage system unit means a hot water storage system having the safety devices described in 3.10 and 3.17 of this Approved Document and all other applicable operating devices factory-fitted by the  manufacturer. Indirect heating means a method of heating stored water through a heat exchanger. Kitchen means a room or part of a room which contains a sink and food preparation facilities Material alteration means an alteration which results in a building or a controlled service or fitting not complying with, or being more unsatisfactory than it was before in relation to Schedule 1 requirements in relation to structure, means of warning and escape, internal and external fire spread, fire service access and facilities, and access and use. Non-self-resetting energy cut-out means a device that will interrupt the supply of heat to a hot water storage vessel when a fixed (factory set) temperature is exceeded. If this protective device is actuated it should only be possible to reset it manually. Preparation of food means handling, making and cooking of food. Pressure relief valve means a mechanically operated valve that opens to discharge water when a fixed (factory set) pressure is exceeded. Primary thermal store means a store of heat energy that can be used to heat domestic hot water by means of a heat exchanger. The thermal store can be heated by a variety of heat sources. Primary hot water thermal stores can be either vented or unvented. Risk assessment for the purposes of this document means the identification of the hazards associated with a process or activity combined with an assessment of the probability and consequences of each hazard. *Room for residential purposes means a room, or a suite of rooms, which is not a dwelling- house or a flat and which is used by one  or more persons to live and sleep in, and  includes a room in a hostel, a hotel, a boarding house, a hall of residence or a residential home, but does not include a room in a hospital, or other similar establishment, used for patient accommodation. Sanitary accommodation means a room containing a WC or urinal, whether or not it also contains other sanitary appliances. Sanitary accommodation containing one or  more cubicles counts as a single space if there is free circulation of air throughout the space. Sanitary appliance means WC, urinal, bath, shower, washbasin, sink, bidet and drinking fountain. It also includes appliances that are not connected to a water supply (e.g. composting toilet) or drain (e.g. waterless urinal). *Sanitary convenience means closets and urinals. Sink means a receptacle used for holding water (for preparation of food or washing up) supplied through a tap and having a wastepipe. *Softened wholesome water means water which would be regarded as wholesome for the purposes of regulations made under section 67 of the Water Industry Act 1991 (standards of wholesomeness) as they apply for the purposes of Part G of Schedule 1 in accordance with paragraph (2c) but for the presence of sodium in excess of the level specified in those regulations if it is caused by a water softener or water softening process which reduces the concentrations of calcium and  magnesium. Tundish means a device, installed in the discharge pipe from a valve, that provides an air break allowing discharge to be  conducted safely to a place of termination. The tundish also provides a visible indication of a discharge and functions as backflow prevention  device. Temperature relief valve means a mechanically operated valve that opens to discharge water when a fixed (factory set) temperature is exceeded. Unvented (closed) hot water storage system means a vessel fed with cold water from a supply pipe or dedicated storage cistern (without  a vent pipe) and in which water is heated  directly or indirectly. Expansion of the water when it is heated is accommodated either internally or externally and the system is fitted with safety devices to prevent water temperatures exceeding 100˚C, and other applicable operating devices to control primary flow, prevent backflow, control working pressure and accommodate expansion. Urinal means an appliance used for reception and disposal of urine. Vented (open) hot water storage system means a vessel fed with cold water from a dedicated storage cistern. Expansion of the water when it is heated is accommodated through the cold feed pipe. A vent pipe connecting the top of the vessel to a point open to the atmosphere above the cold water storage cistern is provided as a safety device. *Water-closet (WC) means a closet that has a separate fixed receptacle connected to a drainage system and separate provision for flushing from a supply of clean water either  by the operation of a mechanism or by automatic action. Water-closets are also referred to as WCs. Wholesome water means water complying with the requirements of regulations made under Section 67 (Standards of wholesomeness) of the Water Industry Act 1991. The regulations made under this Section at the time of  publication of this Approved Document are for England the Private Water Supplies Regulations 2009 (SI 2009/3101), for Wales the Private Water Supplies (Wales) Regulations (SI 2010/66) and, for England, the Water Supply (Water Quality) Regulations 2000 (SI 2000/3184 as amended), and, for Wales, the Water Supply (Water Quality) Regulations 2001 (SI 2001/3911 as amended).    

  1. Types of work covered by this Approved Document
    1. Material change of use
      1. Historic buildings
        1. Notification of work
          1. Exemptions
            1. Materials and workmanship
              1. Supplementary guidance and Interaction with other legislation

                Types of work covered by this Approved Document

                Building work Building work, as defined in regulation 3 of the Building Regulations 2010, includes the erection and extension of a building, the provision or extension of a controlled service or fitting,  and the material alteration of a building or a controlled service or fitting. In addition, Building Regulations may apply in cases where the purposes for which or the manner or circumstances in which a building or part of a building is used change in a way that constitutes a material change of use. Under regulation 4 of the Building Regulations 2010, building work should be carried out in such a way that, on completion of  work,

                i. the building complies with the applicable Parts of Schedule 1 of the Building Regulations,

                ii. in the case of an extension or material alteration of a building, or the provision, extension or material alteration of a controlled service or fitting, where it did not comply with any such requirement, it is no more unsatisfactory in relation to that requirement than before the work was carried out.

                Work described in Part G concerns the provision or extension of controlled services or  fittings. Work associated with installations covered in these sections may be subject to other relevant Parts of the Building Regulations.

                Material change of use

                A material change of use occurs in specified circumstances in which a building or part of a building that was previously used for one purpose will be used in future for another. Where there is a material change of use the Building Regulations set requirements that must be met before the building can be used for its new purpose. Regulation 5 of the Building Regulations specifies the following circumstances as material changes of use:

                • a building is used as a dwelling where previously it was not
                • a building contains a flat where previously it did not
                • a building is used as an hotel or boarding house where previously it was not
                • a building is used as an institution where previously it was not
                • a building is used as a public building where previously it was not
                • a building no longer comes within the exemptions in Schedule 2 to the Building Regulations where previously it did
                • a building which contains at least one dwelling contains a greater or lesser number of dwellings than it did previously
                • a building contains a room for residential purposes where previously it did not
                • a building which contains at least one room for residential purposes contains a greater or lesser number of such rooms than it did previously
                • a building is used as a shop where previously it was not
                Parts G1, G3(1) to (3) and G4 to G6 will apply to all the material changes of use mentioned above. This means that whenever such changes occur the building must be brought up to the standards required by Parts G1 and G3 to G6. Parts G2, G3(4) and regulation 36 will apply only to material changes of use where a building is used as a dwelling where previously it  was not and where a building contains a flat where previously it did not.

                Historic buildings

                The types of building work covered by this Approved Document may include work on historic buildings. Historic buildings  include:

                a. listed buildings

                b. buildings situated in designated conservation areas

                c. buildings which are of architectural or historic interest and which are referred to as a material consideration in a local authority’s development plan

                d. buildings of architectural and historical interest within national parks, areas of outstanding or natural beauty and world heritage sites.

                Special considerations may apply if the building on which the work is to be carried out has special historic or architectural value, and compliance with the sanitation or hot water safety requirements would unacceptably alter the character or appearance of the building or parts of  it. When undertaking work on or in connection with buildings with special historic or architectural value, the aim should be to improve sanitation and hot water safety where and to the extent that it is possible provided that the work does not prejudice the character of the host building or increase the risk of long-term deterioration to the building’s fabric or fittings. In arriving at a balance between historic building conservation and sanitation or hot water safety requirements, it would be appropriate to take into account the advice of the local authority’s conservation officer before work begins. Guidance is also available in the English Heritage publication Building Regulations and Historic Buildings, 2002 (revised 2004), which is available at www.english-heritage.org.uk. Note: Any building in the schedule of monuments maintained under section 1 of the Ancient Monuments and Archaeological Areas Act 1979 is  exempt from all Building Regulations requirements including those in Part G.

                Notification of work

                In almost all cases of new building work it will be necessary to notify a BCB in advance of any work starting. There are two  exceptions to this: where work is carried out under a self- certification scheme listed in Schedule 3, and where work is listed in Schedule 4 to the Building Regulations as being not notifiable. Competent person self-certification schemes under Schedule 3 Under regulation 12(6) of the Building Regulations it is not necessary to notify a  BCB in advance of work which is covered by this Approved Document if that work is of a type set out in column 1 of Schedule 3 to the Regulations and is carried out by a person registered with a relevant self-certification (competent persons) scheme as set out in column 2 of that Schedule. In order to join such a scheme a person must demonstrate competence to carry out the  type of work the scheme covers, and also the ability to comply with all relevant requirements in the Building Regulations. Details of current schemes including those relating to sanitation, hot water safety and water efficiency can be found at www.gov.uk. These schemes may change from time to time, or schemes may change name, or new schemes may be authorised; so the current list on the website should always be consulted. Full details of the schemes can be found on the individual scheme websites. Where work is carried out by a person registered with a competent person scheme, regulation 20 of the Building Regulations and regulation 20(1) of the Building (Approved Inspectors etc.) Regulations 2010 require that the occupier  of the building be given, within 30 days of the completion of the work, a certificate confirming that the work complies with all applicable Building Regulation requirements. There is also a requirement that the BCB be given a notice that this has been done, or a copy of the certificate, again within 30 days of the completion of the work. These certificates and notices are usually made available through the scheme operator. BCBs are authorised to accept these certificates as evidence of compliance with the requirements of the Building Regulations. However, local authority inspection and enforcement powers remain unaffected, although they are normally used only in response to a complaint that work does not comply. Work which is not notifiable under Schedule 4 Schedule 4 to the Building Regulations sets out types of work where there is no requirement to notify a BCB that work is to be carried out. These types of work are mainly of a minor nature where there is no significant risk to health, safety, water efficiency or energy efficiency. Health, safety, water efficiency and energy efficiency requirements continue to apply to these  types of work; only the need to notify a BCB has been removed. Where only non-notifiable work as set out in Schedule 4 is carried out, there is no requirement for a certificate confirming that the work complies with Building Regulation requirements to be given to the occupier or the BCB. The types of non-notifiable work in Schedule 4 relevant to the sanitation, hot water safety and water efficiency provisions of the Regulations are: i. in an existing hot water system, the replacement of any part which is not a combustion appliance, or the addition  of an output device or control device. The work will however remain notifiable where commissioning is possible, and will affect the reasonable use of fuel and This is most likely to be where water heaters are being provided ii. the installation of a stand-alone, self-contained fixed hot water appliance. This is restricted to a single appliance and any associated controls and must not be connected to, or form part of, any other fixed building service. However, if any of the following apply, the work will remain notifiable building  work:

                • the service is a combustion appliance
                • any electrical work associated with the installation is notifiable
                • commissioning is possible and would affect the service’s energy efficiency, such as that of water heaters
                iii. the replacement of a sanitary convenience with one that uses no more water than the one it replaces, a washbasin, sink, bidet, fixed bath, or a shower but only where the work does not include any work to:
                • underground drainage
                • the hot or cold water system or above- ground drainage which could prejudice the health and safety of any person on completion of work
                iv. replacing any part or adding an output or control device to an existing cold water supply v. providing a hot water storage system that has a storage vessel with a capacity not exceeding 15 litres provided that any electrical work associated with the installation is also not notifiable. Schedule 4 also sets out what types of electrical installation work in dwellings is  non-notifiable. Full information on this is given in Approved Document P.

                Exemptions

                Schedule 2 to the Building Regulations sets out a number of classes of buildings which are exempt from all Building Regulations requirements. However, the exemption has been removed in respect of some requirements of Part G where hot or cold water supply systems are shared with other buildings. This is to help ensure that the whole hot or cold water system is safe. In particular:

                i. the requirements of Parts G 1, G3(2) and G3(3) will apply to any greenhouse which receives a hot or cold water supply from a source shared with or located inside a dwelling

                ii. the requirements of Parts G1, G3(2) and G3(3) will apply to any small detached building falling within Class 6 of Schedule 2 and any extension falling within Class 7 of Schedule 2 (which includes conservatories under 30 m2 in area) which receives a hot or cold water supply shared with or located inside any building that is subject to the  Regulations.

                Please note that the Regulations do not require the provision of hot or cold water systems to such exempt buildings, but if such systems are provided they must meet the minimum hygiene and safety requirements in those Parts. All other Classes of buildings within Schedule 2 retain their exemption from compliance with Part G.  

                Materials and workmanship

                Any building work which is subject to the requirements imposed by Schedule 1 to the Building Regulations shall be carried out in accordance with regulation 7. Guidance on meeting these requirements on materials and workmanship is contained in Approved Document 7. Building Regulations are made for specific purposes, primarily the health and safety, welfare and convenience of people and for energy conservation. Standards and other technical specifications may provide relevant guidance to the extent that they relate to these considerations. However, they may also address other aspects of performance or matters which, although  they relate to health and safety etc., are not covered by the Building Regulations. When an Approved Document makes reference to a named standard, the relevant version of the standard to which it refers is the one listed at the end of the publication. However, if this version has been revised or updated by the issuing standards body, the new version may be used as a source of guidance provided it continues to address the relevant requirements of the Regulations.

                Supplementary guidance and Interaction with other legislation

                Supplementary guidance The Department for Communities and Local Government occasionally issues additional material to aid interpretation of the  guidance in Approved Documents. This material may be conveyed in official letters to chief executives of local authorities and Approved Inspectors and/or posted on the websites accessed through: www.gov.uk. Interaction with other legislation This Approved Document makes reference to other legislation, including those listed below, that may also need to be considered. Note: All statutory instruments can be accessed at www.legislation.gov.uk. The Water Supply (Water Quality) Regulations 2000 (SI 2000/3184 as amended), and in Wales the Water Supply (Water Quality) Regulations 2001 (SI 2001/3911 as amended) are made under the Water Industry Act 1991 and apply to the supply of water by a statutory water  undertaker or a licensed water supplier. They make provision for the wholesomeness of water supplied  for such domestic purposes as consist in or include cooking, drinking, food preparation or  washing; or to premises in which food is  produced. The Water Supply (Water Fittings) Regulations 1999 (SI 1999/1148 as amended) are made under the Water Industry Act 1991 and apply to any water fitting installed or used, or to be  installed or used, in premises to which water is or is to be supplied by a water undertaker. They make provision for preventing contamination, waste, misuse, undue consumption and erroneous measurement of water supplied by a statutory water undertaker or licensed water supplier. The Private Water Supplies Regulations 2009 (SI 2009/3101) in England and The Private Water Supplies (Wales) Regulations 2010 (SI 2010/66) in Wales are made under the Water Industry Act 1991 and section 2(2) of the European Communications Act 1972 and are concerned with the quality of water supplied from private supplies for drinking, washing or cooking or for food preparation purposes. The Workplace (Health, Safety and Welfare) Regulations 1992 (SI 1992/3004 as amended) are made under the Health and Safety at Work etc. Act 1974 and apply to any workplace or part of a workplace. They apply to the common parts of flats and similar buildings if people such as cleaners, wardens and caretakers are employed to work in these common  parts. They make provision for, amongst other matters, space requirements, cleaning and provision of sanitary conveniences. Food Hygiene (England) Regulations 2006 (SI 2006/14 as amended) and the Food Hygiene (Wales) Regulations 2006 (SI 2006/31 W5 as amended) are made under European Communities Act 1972 and apply to measures relating to food (including drink) including the primary production of food. The provision of washbasins and sinks is relevant to Approved Document G. Gas Safety (Installation and Use) Regulations (SI 1998/2451) extend to all dangers arising from the transmission, distribution, supply or use of gas conveyed from a gas storage vessel. The installation of gas heated water systems is relevant to Approved Document G.

                • 1 Typical discharge pipe arrangement 1 Typical discharge pipe arrangement
                • 2 Separation between hand washbasin or WC and food preparation area - single room 2 Separation between hand washbasin or WC and food preparation area - single room
                • 3 Separation between hand washbasin or WC and food preparation area - two rooms 3 Separation between hand washbasin or WC and food preparation area - two rooms
                • Table 2.1 Maximum fittings consumption Table 2.1 Maximum fittings consumption
                • Table 2.2 Maximum fittings consumption optional requirement level Table 2.2 Maximum fittings consumption optional requirement level
                • Table 3.1 Sizing of copper discharge pipe 'D2' for common temperature relief valve outlet sizes Table 3.1 Sizing of copper discharge pipe 'D2' for common temperature relief valve outlet sizes
                • Table A1 The water efficiency calculator Table A1 The water efficiency calculator
                • Table A2.1 Consumption calculator for multiple taps Table A2.1 Consumption calculator for multiple taps
                • Table A2.2 Consumption calculator for multiple baths Table A2.2 Consumption calculator for multiple baths
                • Table A2.3 Consumption calculator for multiple taps Table A2.3 Consumption calculator for multiple taps
                • Table A2.4 Consumption calculator for multiple dishwashers Table A2.4 Consumption calculator for multiple dishwashers
                • Table A2.5 Consumption calculator for multiple washing machines Table A2.5 Consumption calculator for multiple washing machines
                • Table A2.6 Consumption calculator for multiple showers Table A2.6 Consumption calculator for multiple showers
                • Table A2.7 Consumption calculator for multiple WCs Table A2.7 Consumption calculator for multiple WCs
                • Table A3 Water softener consumption calculation Table A3 Water softener consumption calculation
                • Table A4.1 Greywater demand calculations - WCs Table A4.1 Greywater demand calculations - WCs
                • Table A4.2 Greywater demand calculations - washing machines Table A4.2 Greywater demand calculations - washing machines
                • Table A4.3 Greywater collection calculations - taps Table A4.3 Greywater collection calculations - taps
                • Table A4.4 Greywater collection calculations - showers Table A4.4 Greywater collection calculations - showers
                • Table A4.5 Greywater collection calculations - baths Table A4.5 Greywater collection calculations - baths
                • Table A4.6 Greywater collection calculation Table A4.6 Greywater collection calculation
                • Table A5.1 Rainwater collection calculation - BS 8515 intermediate approach Table A5.1 Rainwater collection calculation - BS 8515 intermediate approach
                • Table A5.2 Rainwater collection calculation - BS 8515 detailed approach Table A5.2 Rainwater collection calculation - BS 8515 detailed approach
                • Table A5.3 Rainwater demand calculations - WCs Table A5.3 Rainwater demand calculations - WCs
                • Table A5.4 Rainwater demand calculations - washing machines Table A5.4 Rainwater demand calculations - washing machines
                • Table A5.5 Rainwater saving calculations for new dwellings Table A5.5 Rainwater saving calculations for new dwellings