Report on the Review of the Building Code: 9.4 Type 2 recommendations to consult on proposals to change performance requirements

Type 2 recommendations are recommendations to consult on proposals to amend the Building Code involving new performance requirements, changes to the scope of requirements, or different approaches to describing requirements. These would be prepared in conjunction with Compliance Documents to provide guidance to the sector, subjected to benefit/cost analysis, a regulatory impact assessment, and consulted on with Cabinet approval before being finalised.

It is recommended that amendments to the Building Code and related Compliance Documents be prepared for consultation on the proposals in the following section.

9.4.1 General

It is proposed to add to the General section some requirements to apply to all aspects of new buildings or building work.

9.4.1.1 General principles

General principles are proposed that should be stated as requirements in the Building Code.

It is proposed to include in the Building Code a statement of these general principles.

• Effects on adjacent buildings: a building or building work should not cause adjacent buildings to be affected by any of the design events that impact on buildings.
• Disproportionate consequences: the failure of a building element or system should not result in a consequence disproportionate to the event that caused the failure.
• Consequences of failure: building elements should be constructed in a way that makes due allowance for the consequence of failure.
• Effect of uncertainties: building elements should be constructed in a way that makes due allowance for the effects of uncertainties arising from design and construction processes, including variations in the properties of building materials, workmanship, site conditions and the demands on buildings.

9.4.1.2 Performance framework

The Building Code is not clear about which impacts society will tolerate.

A performance framework has been developed that relates performance requirements for buildings to the events and physical conditions that buildings might be subject to. The performance framework also considers the impacts society would be prepared to tolerate for different types of buildings.

The Building Code does not specify the events and physical conditions that designers must consider.

It is proposed to include in the Building Code the events and physical conditions stated in Table 1 (see Appendix 3) that designers must consider buildings to be subjected to.

In practical terms, the performance framework would be incorporated in Compliance Documents.

Analysis of the tsunami risk for coastal areas indicates it to be at least as significant to New Zealand as seismic risk and, for coastal areas, probably much higher. The Building Code cannot economically mitigate the risk of tsunami for all buildings. However the 'essential services' nature of performance group (PG) 4 buildings, and the strategic nature of, and the large population at risk associated with, PG 5 buildings suggests these should designed to be more resilient. (Performance groups are defined in Table 2, Appendix 3.)

It is proposed that PG 4 and 5 buildings be designed and constructed to withstand tsunami where the tsunami risk has been identified on District Plans.

The Building Code requires that 'surface water (flood) with a 2 percent Annual Exceedance Probability (AEP) must not enter buildings 'to prevent the risk of flooding affecting a building'. Some regional councils require that 'surface water with a 1 percent AEP must not enter buildings'.

A 1 percent AEP (1-in-100-year flood) is a more stringent test than a 2 percent AEP (1 in 50 year flood) because it anticipates a higher surface water level. A 1 percent AEP reflects the planning controls generally adopted by regional and local councils, and provides a precautionary approach to the impact of more-frequent and higher-intensity rain predicted as a result of climate change.

It is proposed that buildings be designed and constructed to avoid surface water (flood) with a 1 percent AEP entering them.

Where land use is based on 1 percent AEP, this change would not result in any cost impact. In local authorities where land use is based on 2 percent AEP, there could be additional costs to ensure floor levels are higher than at present.

The Department intends to work with regional councils and territorial authorities to establish the likely impact of this proposed change and the subsequent construction costs, and to prepare a benefit/cost analysis before finalising this proposal.

The Building Code aims to provide reasonable protection from the effects of demands on buildings. However, building codes cannot eliminate all risk. To attempt to do so would result in a restrictive code and expensive buildings: more expensive than society would be prepared to pay.

Society therefore tolerates some impacts on buildings in some circumstances. The impacts that are tolerated depend partly on the size of the event that caused them: a small amount of damage may be tolerated in a small earthquake and a large amount of damage tolerated in a large earthquake. Society's tolerance of impacts also depends on the likelihood that an event will happen. The Building Code is not clear about which impacts society will tolerate.

Table 4 (see Appendix 3) describes impact levels ranging from 'insignificant' to 'extreme'. These set out what society might tolerate in terms of:

• impacts for occupants
• economic impacts
• social impacts
• environmental impacts.

It is proposed that a table of tolerable impacts related to events and physical conditions and performance groups be introduced to the Building Code.

It is proposed that the design of buildings must be such that there is at least 90 percent confidence that buildings meet the applicable tolerable impact requirements, according to the performance group and range of events to be considered.

It is proposed that all buildings must meet the 'Insignificant' tolerable impact requirement for physical conditions that could affect buildings all the time.

These proposals would provide a framework for the preparation of Compliance Documents and any Standards that might be cited in them, and are not likely to add to design, compliance or construction costs.

Society's tolerance of impacts also depends on how vulnerable the people in the building are and how important the building is to society.

Table 2 (see Appendix 3) classifies different types of buildings into five main performance groups depending on factors such as the:

• function of the building
• proportion of time the building is occupied by people
• familiarity of occupants with the building
• number and/or density of people likely to be in the building
• vulnerable or special populations using the building.

This classification of buildings is based on performance groups developed by the International Codes Committee (ICC), a body that provides model building codes. Buildings that are not normally occupied, such as farm buildings, would be in the lowest performance group. Buildings expected to continue functioning after a very large event, such as hospitals or emergency services buildings, would be in PGs 4 and 5. Most buildings in New Zealand would fall within PG 2.

The proposals for amendments to the Building Code recognise the special nature of some New Zealand buildings. For example, back-country huts (such as some Department of Conservation huts) and some farm buildings are classified as PG 1 to recognise the low risk to people because they are typically for transitory or occasional use.

It is proposed that buildings be classified into performance groups according to Table 2 (Appendix 3).

The Department has, independently of this review, consulted on citing in the Compliance Documents AS/NZS 1170 Structural Design Actions, which in effect includes these performance groups.

9.4.1.3 Meeting the performance requirements for the intended life of the building

The principles of the Act include the requirement to take into account:

• the importance of ensuring that each building is durable for its intended use
• the costs of a building (including maintenance) over the whole of its life.

Performance for intended life, durability and maintenance

Buildings are made up of individual elements, but also of systems, such as a roof or cladding, where individual elements work together to perform a building function. If buildings are to continue to perform over time, it is important that both the individual elements and systems of a building are durable and suitable for the environment where the building is located. This requires designers to take account of the physical conditions that affect building performance over time.

The Building Code is not explicit about the physical conditions affecting the performance of buildings that need to be considered. It requires building elements to last for a certain length of time with normal maintenance: five years, 15 years, or for the life of the building, depending on whether or not:

• the element is easy to access and replace
• failure of the element would go undetected during use or maintenance
• the element performs a structural function.

These time periods do not necessarily reflect how consumers expect building elements to perform. They can also provide a disincentive for the building industry to develop products that last longer. The term 'normal maintenance' is not clearly defined in the Building Code, leading to uncertainty about what should be expected for durability.

It is proposed that a building must be designed, constructed and capable of being maintained to provide confidence that it will comply with the performance requirements of the Building Code throughout its life.

It is proposed that the designer state an 'intended life' for a building and demonstrate that it will meet the requirements of the Building Code for that time. An 'intended life' of at least 100 years will be required where the building or building work has 'permanent' effects on other property.13

It is proposed that the Building Code incorporate the physical conditions that are likely to affect the performance of a building over its intended life, as in Table 1 (see Appendix 3).

It is proposed that building designers state the frequency of maintenance or replacement of building systems and how this should be done, to satisfy the building consent authority that the proposed maintenance and replacement arrangements are practicable and are a viable means of achieving compliance for the life of a building.

It is proposed that information about maintenance be included in the documentation provided in a building consent application, so that it is available to future owners of the building.

The intent of these proposals is to give building owners information about the intended life for the building and confidence that maintenance and replacement of building elements is practicable.

Submitters commented that producing the documentation required for this information would add significantly to the cost of design and obtaining a building consent. It is recommended that guidance be provided to designers by way of Compliance Documents (and other information) to minimise the impact on compliance costs.

9.4.2 Structural performance

9.4.2.1 Performance framework for structure

The Building Code specifies general performance requirements for the structural design of buildings and building elements. It sets out the physical conditions likely to affect the integrity and stability of buildings over their intended lives, but it does not quantify what is acceptable building performance under the influence of these physical conditions. This information is currently implicit in the Standards cited in the Compliance Documents. Setting the performance level more explicitly in the Building Code would improve consistency in how the safety requirements are expressed.

It is recommended that the designer for structural performance consider:

• the physical conditions that affect the structural performance of buildings
• the chances of an event occurring
• the performance group of the building
• the impacts that can be tolerated for a range of circumstances.

These proposals would provide a framework for the preparation of Compliance Documents and any Standards that might be cited in them, and are not considered to add to design, compliance or construction costs.

9.4.2.2 Concurrent events and physical conditions

Events and physical conditions on buildings, such as earthquakes or people loads, do not happen in isolation. A designer will often need to take into account combinations of such events.

The Building Code does not clearly set out which events and physical conditions need to be considered as acting concurrently, nor how they need to be considered. This information is included in the joint New Zealand and Australian Standard AS/NZS 1170 Structural Design Actions, but it does not cover all likely concurrent scenarios.

It is proposed that the Building Code be amended to clarify the requirements for addressing concurrent events and physical conditions.

9.4.3 Fire and other emergency

9.4.3.1 Exposure to high levels of sound from alarms used for evacuation

Excessively loud alarms can harm people who are unable to evacuate a building unaided and may be required to remain in a place of safety until they can be helped from the building. For example, hearing can be impaired after one minute at 112 dB(A), after eight minutes at 103 dB(A), or after 15 minutes at 100 dB(A).

While this is a risk that could be tolerated in the event of an emergency, that is likely to be very rare. Trial evacuations and false alarms are more likely, and harm is less tolerable. This hazard is not addressed in the Building Code.

In some situations, ambient noise is very loud (eg, in a factory or at a night club). If the alarm sound level is too low, it will by masked by operational sound and will not be readily detected. So in loud spaces alarm levels must be higher to be heard.

It is proposed that for all buildings where alarms used for evacuation are required, the audible signal in a place of safety be not more than LAmax 100 dBA at any normally accessible point in the room at a height of 1.8 m, or no more than 15 dBA greater than the ambient noise, whichever is the greater.

This is not considered to alter what is current practice, and would therefore have no cost implication. It would provide protection in the future where an evacuation scheme explicitly provides for people to remain in a place of safety during evacuation.

9.4.4 Features for wellbeing and physical independence

9.4.4.1 Access to, within and from a building

Access requirements to, within and from buildings include, but are not restricted to, access for people with disabilities. Schedule 2 of the Building Act 2004 lists the buildings that require access and facilities for people with disabilities. This means not only wheelchair users, but also people with any kind of physical or sensory impairment or limitation, permanent or temporary, including people on crutches and people with infants in pushchairs.

The Building Code has provisions for access routes and mechanical installations for access. These are detailed prescriptive requirements, which do not fit readily with the concept of a performance-based code, but they are clear. The New Zealand Standard NZS 4121 Design for Access and Mobility, Buildings and Associated Facilities provides a means of compliance with the Building Code and is cited in section 119 of the Building Act.

Support was expressed in consultation for 'adaptable' designs. An 'adaptable' home has features that can be adjusted easily and cost-effectively in the future to provide features for people with disabilities - for example, designing walls to allow for the attachment of grab bars at a later date. This would also include meeting the changing needs of older people so they are able to remain in their own homes for longer.

Support for universal design principles was also expressed in consultation - that is, that all elements and spaces should be accessible to, and usable by, people of all ages and abilities to the greatest extent possible. However, it was suggested that these should be issued as guidelines rather than Building Code requirements.

The principles of adaptability and universal design have informed several of the Building Code proposals:

• the framework for fire safety takes into account the movement times for people with disabilities
• a proposed requirement for space for mobility in household units
• wayfinding provisions for people, including people with disabilities
• a general principle that where shared facilities are provided in buildings they should be accessible for people with disabilities.

It is proposed that:

• at least one access route with features for people with disabilities be provided in multi-unit dwellings
• common spaces in multi-unit dwellings be accessible
• where shared facilities for access, parking provisions and sanitary facilities are provided in buildings, they should be accessible for people with disabilities. This would be applied to shared laundry facilities at hostels, motels and multi-unit dwellings (this is required only for camping grounds at present).

The Department heard comments through submissions that having NZS 4121 and Acceptable Solutions could cause confusion and problems for compliance.

It is recommended that all Compliance Documents and guidance materials be reviewed during the course of the implementation of this review.

It is also recommended that guidance on features that will improve the general accessibility and adaptability of the buildings be published for designers.

9.4.4.2 Noise control

Population density in New Zealand is increasing. People are increasingly living closer to one another and in situations where noise can become a serious problem.

The Building Code includes provisions for noise from internal airborne sound and internal impact sound, but does not contain provisions for protection against:

• environmental noise in specified noise zones (such as near traffic, airports, ports and industry)
• noise from building services, such as plumbing services and air-conditioning equipment
• noise from common spaces, such as corridors, courtyards or lobbies
• noise from occupied spaces that do not directly adjoin the household unit under consideration
• noise that enters rooms through flanking paths such as pipes or junctions
• the noise characteristics of non-residential occupancies.

Surveys of apartment residents have shown that the Building Code requirements are insufficient to achieve an indoor noise environment that is acceptable to many residential occupants.

It is proposed that, for residential accommodation in apartment buildings and teaching spaces:

• insulation against airborne noise be based on 80 Percent Population Satisfaction
• insulation against impact noise be based on 80 Percent Population Satisfaction

An initial assessment is that the additional cost for a two bedroom multi-unit apartment would be $6,000 with a benefit/cost ratio of 1.4:1. The benefits are derived from an assessment of willingness to pay for noise control, and improved health outcomes resulting in fewer doctors' visits and admissions to hospital.

There are no Building Code requirements for noise protection in teaching spaces such as classrooms, drama rooms, assembly halls and gymnasiums. Children are particularly sensitive to the effects on intelligibility created by sound reflections off surfaces in teaching spaces and the masking effects of extraneous noise. Improving the acoustic environment in teaching spaces would improve educational outcomes for New Zealand students and the health and wellbeing of teachers.

It is proposed that the reverberation time (expressed in seconds for specific teaching spaces) be specified.

An initial assessment is that the additional cost compared with the present Building Code would be approximately $10,000 per classroom, with a benefit/cost ratio of 68:1.

The Ministry of Education already specifies that construction for state schools should comply with AS/NZS 2107: 2000 Acoustics - Recommended design sound levels and reverberation times for building interiors, which is very similar to the proposed performance requirement. For integrated and independent schools, the Ministry uses the same measure as recommendations and guidelines. The proposal for the Building Code would have only a minor impact, if any, compared with construction to the Ministry of Education guidelines.  

9.4.5 Environment

Indoor climate covers the respiratory quality of indoor air, the indoor air temperature and the moisture conditions required for health and comfort.

9.4.5.1 Indoor air quality

The Building Code addresses indoor air quality by requiring spaces within buildings to have a means of ventilation with outdoor air that will provide an adequate number of air changes to maintain air purity, but it does not describe the level of purity required.

The Compliance Documents state that the acceptability of indoor air purity for workplaces may be verified by demonstrating that contaminant levels do not exceed the limits recommended in the Workplace Exposure Standards and Biological Exposure Indices for New Zealand 1992.

In 2005, the World Health Organization (WHO) stated that 'It is reasonable now to propose using the same air quality guidelines for both indoor and outdoor exposures'. Table 3 (Appendix 3) sets out the maximum contaminant exposure levels based on New Zealand ambient standards or guidelines that are consistent with levels published by the WHO or Health Canada standards, which are internationally recognised.

It is proposed that the maximum design levels for the most common contaminants of indoor air be as set out in Table 3 (Appendix 3).

There would be no requirement for the indoor air to be measured to determine the concentrations of these contaminants. Compliance Documents would provide methods to calculate the volume of fresh air required to satisfy these requirements.

For indoor air quality where other contaminants are present (such as from industrial processes), it is proposed to cite the Workplace Exposure Standards effective from 2002 and the Hazardous Substances and New Organisms Act 1996 in the Building Code.

9.4.5.2 Thermal control

The Building Code has a requirement that a minimum indoor air temperature of 16ºC is able to be maintained in aged care facilities and early childhood centres only. The Building Code does not specify a minimum indoor air temperature requirement for other buildings, and there is no requirement for a maximum indoor temperature.

The World Health Organization recommends a minimum indoor temperature for health of 18ºC, with up to 20-21ºC for more vulnerable groups, such as older people and young children.

The performance requirements for thermal conditions should acknowledge the interactions between temperature (air, radiant), humidity and air velocity (draught), as well as how much clothing is worn and the level of activity undertaken by building occupants.

The proposals set a level of building thermal performance that would require specific consideration of energy-efficient design.

It is proposed that:

• habitable spaces of buildings where people work and habitable spaces where people live be able to maintain a thermal environment that is likely to satisfy 85 percent of the population (85 PPS)
• the energy demand for spaces of buildings where people work and habitable spaces where people live takes account of an 85 PPS thermal environment.

Compliance Documents would provide guidance to designers about how this performance could be achieved. A Verification Method would provide design methods, and an Acceptable Solution would provide straightforward means of satisfying the performance requirement.

9.4.5.3 Moisture control

This section addresses unwanted moisture indoors as it affects health and comfort, including the likeli-hood of water penetrating the building envelope into habitable spaces.

Unwanted moisture can come from many sources. It can originate outside a building from rainwater, snow, hail, flooding, leaks and spills and can enter a building through the building envelope. Or it can be caused by overflow from an adjoining household unit - for example, a leak from an apartment to the one below.

Unwanted moisture can also originate from within a building as a result of activity such as breathing, cooking, showering and clothes drying. Dampness and condensation promote the growth of harmful bacteria, pathogens and allergens, and mould and fungi in the air, affecting health. When the relative humidity is high enough, harmful organisms, such as mould can grow.

The Building Code requires that residences have an adequate combination of thermal resistance and ventilation in all habitable spaces, bathrooms, laundries and other spaces where moisture may be generated. The Building Code does not specify a measure for the level of humidity required.

Mould only grows where there is a supply of moisture. In buildings, this is either where there is liquid moisture or air with high relative humidity. Air with relative humidity of less than 70 percent is considered to provide an adequate safeguard against conditions that promote the growth of moulds.

It is proposed that:

• the maximum relative humidity in occupied spaces not exceed 70 percent for more than six hours a day in habitable spaces
• the time required for condensation on surfaces in occupied spaces (eg, bathrooms) to evaporate shall be limited to less than three hours.

Compliance Documents would prescribe how these conditions could be achieved through heating, insulation and ventilation.

[Type 2 recommendations for the General section address the effects of external moisture on building elements (typically durability and structural integrity).]

9.4.6 Safety of users

9.4.6.1 Protection from hot surfaces and substances

The Building Code addresses protection of people from temperature extremes for water and piped services, but does not address other hot surfaces. Injury Prevention Research Unit statistics show that burns are one of the five major causes of injury in New Zealand. The young, older people and the infirm are more susceptible than others to the risk of burns from hot surfaces.

Below 50°C the risk of burns is low.

It is proposed that access to surfaces or substances of a temperature higher than 50ºC should be restricted, except for cooking elements, in early childhood centres, schools, aged care facilities, care facilities for people with psychiatric or physical disabilities, and hospitals.

The Building Code requires that heated water for personal hygiene must be delivered at a temperature that avoids the likelihood of scalding. The Compliance Document specifies that the delivered hot water temperature at any sanitary fixture used for personal hygiene shall not exceed:

• 45°C for early childhood centres, schools, old people's homes, care facilities for people with psychiatric or physical disabilities, hospitals, and
• 55°C for all other buildings.

These figures have been reviewed and a single value of 50°C for the maximum temperature can be specified. This provides adequate protection and is easier to apply.

It is proposed that the temperature of heated water leaving the outlet of personal hygiene facilities must be 50ºC or less (to avoid the likelihood of scalding).

9.4.6.2 Hazardous substances

The Building Code sets out performance requirements for buildings where hazardous substances and processes exist. However, the storage and use of hazardous substances is also subject to the Hazardous Substances and New Organisms Act 1996 (HSNO Act). Buildings used for storing or using hazardous substances must comply with this legislation as well as the Building Code, and the Building Code cannot have less stringent provisions than Regulations under the HSNO Act.

It is proposed that construction requirements for buildings used for storing or using hazardous substances be consistent with the requirements of the Hazardous Substances and New Organisms Act 1996 (HSNO Act).

9.4.7 Sanitation

9.4.7.1 Solid waste disposal

A number of submitters suggested that sanitation features should take sustainable development objectives into account, and that in multi-unit dwellings there was often inadequate storage space for waste and recyclables.

The Building Code has requirements for space and facilities for the collection and safe, hygienic holding before disposal of solid waste arising from the intended use of the building.

It is proposed that for commercial and industrial buildings, multi-unit dwellings and detached dwellings where there is no independent access or private open space at ground level, space must be provided for safe, hygienic storage before collection of waste and recyclable waste, and access for collection.

9.4.7.2 Laundering facilities

The Building Code requires laundry facilities to be accessible to people with disabilities only in camping grounds. However, laundry facilities may be shared in other situations, such as hostels, motels or multi-unit dwellings.

It is proposed that where shared laundry facilities are provided in buildings (eg, multi-unit dwellings, motels, camping grounds) they shall be suitable for use by people with disabilities.

9.4.7.3 Facilities for cleaning

The Building Code does not make provision for facilities for cleaning in commercial and industrial buildings, although earlier regulations did require these. These facilities are usually cleaners' cupboards with a tub for filling buckets and rinsing mops. These facilities are provided in many buildings. In buildings where they are not provided, it is not uncommon for hand basins to be used, which compromises the hygiene of the sanitary facility.

It is proposed that space and facilities for the hygienic use and storage of cleaning equipment be provided in commercial and industrial buildings.

9.4.7.4 Water supplies

The Building Code is concerned with the safety of water for people, as it is delivered at the point of use (generally a tap) whether for drinking or some other purpose.

Storage and distribution of water in tanks and pipes within buildings up to the point of use (generally a tap) is governed by the Building Code. The Code takes over responsibility for water once it leaves a public networked supply and enters a property (usually at the water toby), and also applies to water distributed within a building from its own supply (for example a roof tank or bore).

The Building Code has a requirement that buildings provided with water outlets, sanitary fixtures, or sanitary appliances must have safe and adequate water supplies. There is no explicit required capacity for water supply systems. If a water supply system is not able to meet the requirements for personal consumption and sanitation, there is a risk to the health and wellbeing of building occupants.

The minimum amount of water required to meet essential health and sanitation requirements for the short term has been assessed by the Ministry of Health to be 90 litres per person per day. Reported usage ranges from 60 to 260 litres per person per day.

The Department has no evidence of any failure to provide buildings with sufficient water to meet personal use and sanitation requirements. Many submitters commented that water conservation should be encouraged and, in some cases, recommended consumption levels lower than the minimum supply capacity considered in the discussion document. The Department recommends that development of proposals for resource efficiency (see section 9.5.1) should address whether a backstop supply capacity provision is required to address a possible perverse effect from excessive water conservation measures.

The Building Code requires drinkable water for human consumption, food preparation, utensil washing or oral hygiene. The Building Code does not require water that is used for personal washing, clothes washing and toilet flushing to be safe to drink, but it must be of a standard and provided in a manner that avoids the likelihood of illness.

The Australian Health (Drinking Water) Amendment Act 2007 require that water for personal washing and water for laundry tubs (which may be used for washing dishes and food preparation) must be safe to drink.

The Health (Drinking Water) Amendment Act 2007 and international jurisdictions use the expression drinking water for what the Building Code defines as potable water (and correspondingly, non-drinking for non-potable water).

It is proposed that:

• terminology be changed from potable to drinking water (and correspondingly, from non-potable to non-drinking water)
• water supplied at outlets of fixtures (including laundry tubs) and appliances intended for human consumption, utensil washing, food preparation, oral hygiene and personal washing meet the health quality requirements of the NZ Drinking Water Standard 2005.

Raw water for other uses

Water supplies for 13 percent of New Zealanders come from non-network sources such as springs, bores and tank rainwater. Untreated raw water may or may not be contaminated.

It is proposed that:

• raw water that is supplied from springs, bores and tank rainwater may be used for laundry, toilet flushing or irrigation
• raw water used for these purposes is to have low risk to human health from direct contact
• the level of microbial indicators is not to exceed 10 E.coli/100ml
• raw water supplied at outlets of fixtures and appliances, intended for human consumption, utensil washing, food preparation, oral hygiene and personal washing, is to meet the health quality requirements of the New Zealand Drinking Water Standard 2005.

Distinguishing between drinking and non-drinking water systems

It is important that building users be informed about tap water that is not known to meet drinking water requirements - for example, in back-country huts and other places where the water has not been supplied by a network utility operator. The Building Code has requirements for water outlets provided with non-drinking water to be clearly identified.

It is also important to be able to differentiate between the pipes, valves and outlets that are used to distribute water that is safe to drink and water that is not safe to drink.

It is proposed that water pipes with non-drinking water be continuously identified.

Greywater is water that comes from bathrooms, kitchens and laundries; blackwater comes from toilets and urinals. Domestic wastewater plumbing is usually combined at the sewer, so that grey and black waters are disposed of together using a shared sewerage system.

Greywater requires a high level of treatment to be safe for human contact because of the wide range of possible microbial contamination and the possible public health consequences if it is not properly treated.

Greywater could be stored and used in commercial, industrial and other buildings where treatment and monitoring can take place as part of a compliance regime. Continuous monitoring of stored greywater is required to ensure treatment is maintained. But the management of greywater recycling in domestic buildings may not be adequate to safeguard against disease transmission. The performance of treatment systems would need to be verified.

The same indicator is used as for raw water - E.coli/100ml. E.coli is a measurable indicator of pathogens. However, the level set for greywater is more stringent than for raw water. The different values take into account the greater risk of associated pathogens (bacteria and/or viruses).

Greywater used for subsoil irrigation does not need to be treated as it does not come into contact with humans. However the discharge of greywater in this manner would need to be a permitted activity under a District Plan, or otherwise consented under the Resource Management Act 1991.

The use of greywater as a water conservation measure received considerable support in consultation.

It is proposed that:

• greywater may be re-used within a building to flush toilets
• the level of pathogens in greywater stored for re-use as measured by microbial indicators shall be less than 1 E.coli/100ml
• the quality of stored greywater must be monitored and the system maintained as a specified system
• greywater may used for subsoil irrigation where that is permitted under the Resource Management Act 1991
• greywater directly distributed for subsoil irrigation does not need to be treated.