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Updating a NZ Hazardous Substances Inventory After a Change

September 29, 2026·16 min read

A new solvent arrives at a workshop. The supplier sends a safety data sheet, but the substance goes straight into a cabinet and the workplace inventory stays as it was. Several weeks later the business raises the amount it normally stores. The inventory still lists the old maximum. The file may look complete because it has a date and a spreadsheet tab for the site. It no longer describes the substances that emergency workers and the people managing controls need to know about.

Regulation 3.1 of the Health and Safety at Work (Hazardous Substances) Regulations 2017 requires a PCBU with management or control of a workplace to prepare and keep an inventory of hazardous substances used, handled, manufactured or stored there, and to maintain it so its information is up to date. WorkSafe's inventory guidance explains the practical change triggers. The inventory needs updating when substances change or their maximum quantity likely at the workplace changes. WorkSafe's quick guide also calls out changes to the safety data sheet information and to where substances are located.

This article answers the update-after-change question for a New Zealand workplace. It is not a general explanation of the whole hazardous substances regime. The existing New Zealand hazardous substances overview covers the wider HSWA and EPA context. This page focuses on what makes the inventory stale, what information must be revisited, and how to keep an update traceable. It does not determine whether a particular chemical needs a certified handler, a location certificate or a specific storage control. Those questions depend on the actual substance, quantity and workplace.

The legal duty is to maintain the inventory, not just create it once

The key wording in regulation 3.1 has two parts. The PCBU must ensure an inventory is prepared and kept at the workplace. It must also ensure the inventory is maintained so its information is up to date. A business that created a careful spreadsheet years ago has not discharged the maintenance part merely by retaining the file.

The regulation is tied to a workplace that the PCBU manages or controls. WorkSafe says a business with several such sites needs an inventory for each one. A company-wide master list can help purchasing, but it cannot by itself show which hazardous substances are at each workplace, their likely maximum quantities or their locations. If a substance moves between a warehouse and a workshop, each affected site's information needs checking.

The inventory is not meant to be a daily stock ledger. Regulation 3.1 asks for the maximum quantity likely to be at the workplace for each substance. WorkSafe explicitly explains that keeping an inventory up to date is not a daily calculation of stock held. This distinction matters when a shipment arrives: the quantity on one delivery docket is evidence, but the inventory should state the realistic maximum likely at that workplace. If storage practice changes and the likely maximum rises or falls, revisit the inventory figure.

Do not turn this into a claim that any delivery automatically changes a maximum. Compare the new operating pattern with the recorded likely maximum. A single small refill that stays within the existing pattern may not change that field. A new storage cabinet, an extra bulk container or a changed purchasing cycle may. The person maintaining the inventory should be able to explain why the maximum entered still reflects the site.

What has to be current for each substance

Regulation 3.1 identifies the core information. For each hazardous substance, the inventory includes the product or chemical name and UN number if available, the maximum quantity likely at the workplace, its location, any specific storage and segregation requirements, and the current safety data sheet or a condensed version of key information from it. Hazardous waste is included too. The regulation specifies information about the nature, likely maximum, location and storage or segregation of that waste.

An update should therefore examine more than a name field. If a new product replaces an old one, do not merely edit a cell label while retaining the old safety data sheet or the old storage instruction. If the substance is moved, check the location field. If the supplier issues a revised safety data sheet that changes key storage or segregation information, compare those details with the inventory and the way the product is actually kept.

A practical record can identify the product and manufacturer, the version or date of its safety data sheet, the relevant location, the maximum likely quantity and the person who reviewed the change. These extra tracking fields are a management choice, not a claim that the regulation mandates one spreadsheet format. Their value is that another worker can find the right current document and understand what changed.

Be precise about hazardous waste. An old drum of waste solvent is not outside the inventory merely because the business no longer buys that solvent. The regulation expressly includes hazardous waste and asks for an identifier that describes its nature as closely as possible, along with the likely maximum and location. If waste is generated in a new process or moved to a new collection point, update that part of the site inventory as well.

Triggers that should start an update

The clearest triggers in WorkSafe's guidance are a change in the substances at the workplace and a change in the maximum amounts likely to be there. WorkSafe's inventory quick guide adds that information kept in the inventory can also change when a safety data sheet changes or a substance is moved to a different location. The legal duty is to keep the information current; these are regulator examples of how that duty is engaged.

The following events deserve an inventory check:

A new hazardous substance is introduced for a task, including a trial product.
A product is permanently removed, replaced or renamed by a supplier.
The likely maximum kept at the workplace changes because storage or purchasing practice changes.
A substance moves between rooms, stores, buildings or workplaces.
A safety data sheet is replaced or its key hazard, storage or segregation information changes.
A new process creates hazardous waste or changes the nature or likely maximum of waste already recorded.
A stocktake finds a substance, drum or container that is absent from the inventory.

This list is a practical screening aid. It is not a separate statutory list of seven events. The question is whether the information that regulation 3.1 requires is still correct. A change can affect several fields at once. For example, a new flammable product may add a new entry, change a cabinet's likely maximum and require a review of the location and storage controls.

The best timing is part of the change process, before the new arrangement becomes routine. Procurement, maintenance and supervisors can tell the inventory owner about a proposed change when they know it is coming. That gives the workplace time to obtain the safety data sheet and check storage arrangements. The legal requirement remains an up-to-date inventory; this early notification step is an operational method for meeting it.

A practical update sequence

First, identify which workplace is affected. A central buyer may order a product for several depots, but each depot has its own inventory facts. The delivery address alone may not be enough if the material is moved after receipt. Confirm where it will be used, handled or stored, and where any resulting waste will be kept.

Second, confirm the substance identity. Use the supplier's current safety data sheet and product information. Different formulations can share a familiar trade name, while a rebranded product can have a different safety data sheet. Do not copy classification and storage details from a similar product without verifying the actual substance. If the UN number is available, include it as the regulation specifies.

Third, update the maximum quantity likely at that workplace. Ask what the normal storage arrangement and procurement cycle now permit. This is not a demand to count every container daily. It is a realistic description of the maximum amount likely on site. If the amount is uncertain because a project will temporarily increase stock, document the expected arrangement and review it again when the project ends.

Fourth, update location and storage information. A product in a different store may interact with other substances and controls differently. The inventory should identify where emergency workers can expect to find it. Compare storage and segregation requirements with the current safety data sheet and the site's actual layout. Do not infer that recording the new location alone proves the storage arrangement is safe.

Fifth, attach or reference the current safety data sheet or an accepted condensed version of its key information. WorkSafe's safety data sheet guidance explains that a current document must be kept with the inventory. If a supplier sends a revised sheet, do not just save it in a general email folder. Make the current information available with the inventory and identify what changed.

Sixth, examine control measures and communication. WorkSafe advises reviewing the measures used to manage hazardous substances when the inventory is updated. A new substance may call for different containment, segregation, ventilation, training or emergency arrangements. This article does not prescribe which control is sufficient for a particular site. It tells the business to make the inventory change visible to the people responsible for evaluating those controls.

Finally, record the change and access check. Note what was added or amended, when, who reviewed it and where the updated inventory is kept. Confirm that emergency service workers could access it in the circumstances specified by regulation 3.1, including after evacuation. A file on an employee's locked laptop may be up to date but not readily accessible when that person is absent.

Emergency access is a separate test of quality

Regulation 3.1, paragraph 4 requires the PCBU to ensure the inventory is readily accessible to an emergency service worker attending the workplace, including during an emergency and after evacuation. WorkSafe explains that readily accessible can be achieved in hard copy, electronic or another form if the document can be accessed without difficulty. The right format depends on the site and its emergency arrangements.

Updating the main spreadsheet is only half the job if responders still receive an old printed copy or an outdated export. When an inventory changes, check the route through which emergency workers would get it. Does the site keep a controlled printed copy? Is the electronic version available if power, network access or the normal employee account is unavailable? Who can explain the location of substances during an incident? These are practical access questions, not prescribed universal technology requirements.

A multi-site business should also prevent one site's list from being mistaken for another's. Clear site identifiers and version dates can help. If a contractor temporarily brings a hazardous substance into a workplace, determine which PCBU has management or control of the workplace and how the substance will be reflected in the applicable inventory. Do not assume that the contractor's own product list automatically updates the workplace inventory.

The inventory supports emergency response, but it does not replace an emergency plan or a safety data sheet. Nor does it prove that every control threshold has been met. It is a source of facts about the substances and their likely amounts and locations. Those facts can then inform separate decisions under the applicable regulations and site risk-management process.

Distinguish an SDS change from a stock change

A supplier can revise a safety data sheet even when the workplace continues buying the same product in the same quantity. WorkSafe's quick guide says the inventory should be updated if information on the sheet changes, such as recommended segregation or storage requirements. The maximum likely quantity may stay the same, while the document and control information need attention.

Ask what changed in the new sheet. If it corrects a contact number, the operational effect may be limited. If it revises hazard classification, first-aid information or segregation advice, the people managing training, storage and emergency arrangements may need to review their controls. Do not treat every revised date as proof that all controls changed, or assume a revision has no effect because the product name stayed the same.

Keep a clear link between the inventory entry and the current sheet. If a condensed safety card is used, ensure it reflects the current key information rather than an obsolete version. This is particularly important where different suppliers sell products with similar names. A worker needs information for the substance actually present at that site.

WorkSafe says workers need training and awareness when a new hazardous substance is introduced or the safety data sheet for an existing one changes. The inventory update can trigger that communication, but marking a file as uploaded is not the same as workers understanding the relevant changes. Record who needs to know and how the information will reach them.

The maximum likely amount is not a moving stock count

WorkSafe's explanation of the quantity field prevents a common administrative mistake. The inventory represents the maximum quantity likely at each workplace, not a daily calculation of stock. A daily stock system can still be useful for purchasing or emergency operations, but it is a different record. If a workplace routinely receives a pallet of a substance and then uses most of it during the week, the likely maximum should account for the arrival, not just an average end-of-week amount.

Changes to that likely maximum may affect other regulatory controls, but this article cannot derive those controls from a generic litre figure. The relevant substance classification, aggregation rules and workplace arrangement matter. WorkSafe's inventory page says an update should be followed by a review of the measures used to manage the substances. Use the revised inventory as an input to that review. Refer threshold or certification questions to the relevant official tools and qualified people rather than asserting that one higher number automatically requires a particular certificate.

Where stock temporarily spikes for a project, the workplace should consider whether the recorded likely maximum still describes the situation. A project manager may call the increase exceptional; emergency workers still need reliable information about what is likely to be there during the project. Document the expected period and update again when the arrangement ends. This is a practical way to keep the record aligned with reality, not a newly invented statutory deadline.

Common ways an inventory becomes unreliable

Purchasing changes without site notification. A central team changes suppliers or adds a substitute product, while the site continues using the old inventory entry. Add an inventory check to the purchasing handover for hazardous substances. Verify the actual new product and safety data sheet before copying old information.

One company-wide file masks local differences. The same product may be present in different amounts and locations at two workplaces. A consolidated view can help management, but each workplace inventory must reflect its own facts. Site-specific records also reduce the risk that emergency workers receive an irrelevant list.

A container moves but the record does not. A locked cabinet is relocated during refurbishment, yet the inventory still directs a responder to the former room. Review the location field whenever the storage arrangement changes. Then examine whether segregation and emergency access need attention.

An SDS is filed but not connected to the substance entry. The inventory may refer to an older version or to a different manufacturer's formulation. Link the current sheet or condensed key information to the actual product and check whether its changed advice affects controls.

Waste is forgotten. A process change creates a new hazardous waste stream. The purchasing list may show no new chemical, but regulation 3.1 includes hazardous waste in the inventory. Describe its nature as closely as possible and revisit its likely maximum, location and storage requirements.

An electronic file is only accessible to one person. The regulation requires accessibility to emergency service workers even after evacuation. Check how a responder would obtain the inventory if the normal account holder is absent or the usual office is closed.

These are not reasons to add repetitive daily paperwork. They are reasons to make the inventory part of ordinary site change control. When a real-world fact changes, the person responsible for the inventory should hear about it and update the fields affected.

A short change-control record that works

A workplace can keep a simple update log alongside the inventory. Each entry can identify the site, the substance or waste stream, the change trigger, the old and new information, the safety data sheet checked, the person making the update and any control-review action passed to a responsible person. That format is an operational suggestion. It should not be presented as a legally prescribed form.

Avoid letting the log become the inventory itself. An emergency service worker needs the current, usable list of substances and locations, not a sequence of edits to reconstruct under pressure. Keep the current inventory clearly available and retain version history separately if the business finds it useful. If a control review produces a change to signage, storage or training, link that outcome to the underlying substance change so the decision can be traced.

An update can remain open if a key fact is unknown. For example, the supplier may not yet have provided the current safety data sheet or a manager may not know the likely maximum at a new store. Do not fill the blank with an invented figure to make a dashboard look complete. Resolve the missing information before treating the inventory as current for that substance, and manage the proposed introduction through the workplace's safety process.

Putting the update into practice

1. Identify the affected workplace and the person responsible for its inventory. 2. Confirm the actual substance or hazardous waste and obtain current source information. 3. Compare the name, UN number where available, likely maximum, location, storage and segregation requirements, and safety data sheet information with the existing entry. 4. Update every field affected by the change, including waste details where relevant. 5. Review the control measures and notify people whose work or emergency arrangements depend on the new facts. 6. Check that the current inventory remains readily accessible to attending emergency service workers, including after evacuation. 7. Record the update and set a recheck trigger for the next relevant change.

The decision is simple to state: the record should describe the hazardous substances actually used, handled, manufactured or stored at the workplace and the maximum amounts likely there. The work of keeping it true belongs in daily change control rather than a once-a-year filing exercise.

Where Complys fits

Explore Complys for New Zealand teams for the general product offering. The live overview currently describes inventory and safety data sheet features, but this article does not repeat those claims as verified functionality. It does not say Complys classifies substances, verifies controls, updates an inventory automatically or makes a legal determination. Any specific product workflow should be added only after the actual implementation is checked.