How to Create a Hazardous Substances Inventory for Your Farm (Without the Headache)

If you’re running a farm in New Zealand, you already juggle enough, stock, weather, pasture, machinery, staff, compliance… the list never ends. So when someone tells you that you must have a Hazardous Substances Inventory, it’s easy to roll your eyes and think, “Great, another pile of paperwork.”

But here’s the truth: A proper hazardous substances inventory isn’t just a WorkSafe box‑tick. It’s a tool that protects your workers, your family, your animals, and your farm. And once you know what you’re doing, it’s not nearly as painful as it sounds.

Let’s break it down in plain language.

What Is a Hazardous Substances Inventory (And Why Do You Need One)?

A hazardous substances inventory is simply a list of every hazardous substance on your farm, from diesel to drenches to fertiliser to cleaning agents.

WorkSafe NZ requires every PCBU (yes, that includes farms) to keep an up‑to‑date inventory of all hazardous substances used, stored, or handled on site. This helps you understand what you’ve got, what risks come with it, and what controls you need in place.

It also needs to be readily accessible to emergency services, because if something goes wrong, they need to know what they’re walking into.

Step 1: Walk the Farm and List Every Hazardous Substance

Grab a notebook (or your phone) and do a full walk‑around of the farm. Check:

  • Fuel tanks
  • Sheds
  • Spray stores
  • Workshops
  • Vet rooms
  • Utes and tractors
  • Chemical cupboards
  • Fertiliser storage

You’re looking for anything that could harm people, animals, or the environment.

WorkSafe recommends listing all hazardous substances, including hazardous waste.

Step 2: Record the Key Information for Each Substance

Your inventory must include:

  • Product name
  • UN number (if available)
  • Maximum amount likely to be on site
  • Where it’s stored
  • Storage/segregation requirements
  • A current Safety Data Sheet (SDS) or summary
  • Any hazardous waste

These requirements come directly from WorkSafe NZ.

If you’re not sure where to find the UN number or hazard classifications, check the SDS, usually in Section 1 or 2.

Step 3: Use the WorkSafe Hazardous Substances Calculator

This is the easiest way to create a compliant inventory. WorkSafe’s online calculator lets you enter each substance and automatically tells you what controls apply. It also generates a proper inventory you can save and update.

You’ll need:

  • The product name
  • The HSNO approval number (found on the SDS)
  • The maximum amount you store

Once entered, the calculator gives you:

  • Storage rules
  • PPE requirements
  • Fire safety controls
  • Emergency response info

It’s surprisingly user‑friendly once you get the hang of it.

Step 4: Keep Your SDS Folder Updated

Every hazardous substance must have a current SDS (less than 5 years old). If your supplier hasn’t given you one, ask as they’re legally required to provide it.

Many farmers keep a printed SDS folder in the shed and a digital copy on their phone. Both are fine as long as emergency services can access it quickly.

Step 5: Update Your Inventory Whenever Things Change

Your inventory doesn’t need daily updates, but it must reflect the maximum amount likely to be on site. WorkSafe requires inventories to be kept up‑to‑date. Update it when:

  • You add new chemicals
  • You stop using a product
  • You increase or decrease storage amounts
  • You change storage locations

Step 6: Make Sure It’s Accessible in an Emergency

Emergency services must be able to find it without difficulty.

A laminated copy in the main shed or office works well.

“Readily accessible” means:

  • Not locked away
  • Not buried in a drawer
  • Not saved on a computer nobody can log into

Where Farmers Often Go Wrong

If it can harm someone, it belongs in the inventory.

Common mistakes include:

  • Forgetting about small quantities (“It’s only a bit of spray left in the drum”)
  • Missing hazardous waste
  • Not updating SDSs
  • Not recording maximum quantities
  • Not listing fuel tanks
  • Not including animal health products

Need Help? ChemMatrix.co.nz Makes It Easy

If you’re in Auckland or Waikato, ChemMatrix.co.nz is a specialist Hazardous Substances Consultancy that helps farmers build compliant, practical inventories without the stress. They understand farming and won’t drown you in jargon, just clear, workable solutions.

They can:

  • Audit your current chemical storage
  • Build or update your hazardous substances inventory
  • Help you use the WorkSafe calculator
  • Provide SDS management
  • Advise on storage, segregation, and emergency planning

The Bottom Line

A hazardous substances inventory isn’t just a legal requirement, it’s a safety tool that protects your people, your stock, and your farm.

Once you know what to record and how to keep it updated, it becomes a simple part of running a safe, compliant operation.

And if you want someone to take the load off your shoulders, ChemMatrix.co.nz is a solid partner for farmers across Auckland and Waikato.

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