Fire extinguishers are full of pressurised chemicals, so they can't simply be thrown in the rubbish. You need to take certain steps to make sure it is safe. If the fire extinguisher is not empty, you must empty prior to disposal.
How to safely empty a fire extinguisher
Fire extinguishers contain different substances which are used to put out different types of fires. These substances can be toxic to the environment, so have to be removed from the extinguisher and disposed of in the correct manner.
Powder – this type requires specialist disposal.
Foam – this type can be dispensed into a sewer drain (not rainwater drain).
CO2 – this type can be dispersed into the air.
Water – this type can be poured into a drain.
Where to dispose of an empty fire extinguisher canister
Once fully discharged the cylinder can be dismantled and then recycled using standard metal recycling techniques. Other materials such as plastics and rubber are also recyclable meaning that almost 100% of extinguishers that have reached the end of their life can be recycled.
Fire extinguishers cannot be put into your household recycling bin, but you can take them to larger household waste recycling centres for disposal.
Remember: if you allow the removal of old fire extinguishers from your possession by person or company who does not hold a valid waste license, you as the original extinguisher owner could be prosecuted for not using a license holder.
Old and redundant fire extinguishers can be a potential threat to persons, buildings and the environment. You must dispose of them correctly and ethically.