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Chemical Compatibility and Segregation

Some products react badly when they touch, and some make a fire worse. This guide explains how to find out what should be kept apart on your farm and how to organize storage without relying on guesswork.

Why can't all chemicals be stored together?

Some products release heat, gas or smoke when they mix. Others feed a fire, corrode containers or contaminate each other, even when no one means for them to touch.

Mixing can happen through a spill, a leak, a falling shelf, a flood or a fire. Planning for those events is what segregation is about.

Where do I learn what is incompatible?

The product label and the safety data sheet are the first stops. They describe storage conditions and materials the product should not touch, and they are written for the specific product in your hands.

If the information is unclear, call the manufacturer or supplier, or ask your extension office. Do not trust a chart you found online or a rule of thumb you heard at the co-op.

Make sure the person who restocks shelves has read the sheets too, since misplaced items are a common cause of mixing.

• Read the storage and incompatibility information on the safety data sheet.
• Ask the supplier when a label is unclear.
• Keep the sheets together and up to date.

How should storage be organized?

Group products by what they are and how they behave, not by how often you use them. Keep fertilizers, pesticides, fuels, acids, bases and oxidizing products apart in the ways their labels describe.

Use separate rooms or separate buildings where that is practical, and use physical barriers and spacing where it is not. The distances and construction come from fire codes and local authorities, not from this page.

What about shelves, floors and containers?

Heavy items belong on low, strong shelving, and liquids should sit below dry products so that a leak cannot drip onto them. Containers should stay in their original packaging with labels intact.

If you must transfer a product, use a container made for it, label it fully at once and do not use food or drink containers. Keep lids tight and check for leaks, swelling and corrosion.

Floods and storms can move containers and break shelves, so check storage after severe weather. Look for tipped drums, cracked jugs and damp labels, and separate anything that has shifted next to something it should not touch. If you are unsure whether a product is still safe to use, call the manufacturer or supplier before you do anything else with it.

What should I do about old or unknown products?

Old, unlabeled or damaged containers are a hazard, because you no longer know what is inside or what it might react with. Do not open, mix or pour them out to find out.

Set them aside in a secure spot and call your state department of agriculture or local waste authority about disposal. Many areas run collection programs for old farm chemicals.

How can I keep the system working?

Keep an inventory, review it before each season and walk the storage area on a schedule. Remove what you no longer use, and avoid buying more than you can store properly.

Teach everyone who enters the building how it is arranged and why. A short explanation of why two products are kept apart makes people far more likely to put them back where they belong.

Share the plan with your insurance agent and your fire department, and ask whether they see anything you missed. Fresh eyes catch problems that become invisible after years of familiarity.

What should I do in a spill or a fire?

Segregation is meant to limit what happens when something goes wrong. If products do mix, or a fire starts, get people away and call 911. Do not try to sort it out yourself.

Tell responders what is stored and where. A current inventory and the safety data sheets, kept outside the building, may help them decide how to approach a call safely. Keep a simple map of the storage area on the wall, showing where each group of products belongs. A visual guide helps seasonal workers return items to the right place, and it gives responders a quick picture of what is inside.

• Keep an inventory copy outside the storage building.
• Share the list with your fire department each year.
• Never mix products to clean up or to dispose of them.

Last reviewed: November 12, 2026. Written by the Farm Safety Editorial Team. See our editorial policy.