Wood preservatives can be harmful to the environment and toxic to many animals and plants particularly aquatic life including fish and aquatic insects and plants.

Commonly used wood preservatives for treating wood and timber products include:

  • water-based preservatives, eg alkaline copper quaternary (ACQ), copper azole or other copper-containing solutions or boron compounds
  • solvent-based preservatives, eg permethrins and azoles dissolved in white spirit
  • fire retardant chemicals, likely to contain halogenated organic compounds
  • creosote.

What you must do

All wood preservative and treatment products must be approved under the Control of Pesticide Regulations or the Biocidal Products Regulations (BPR) before they can be sold and used.

If you use a wood preservative or treatment product you must make sure:

  • it has approval from the relevant registration authority
  • you use the substance as instructed on the label and the safety data sheet.

For further information about the approval of pesticide and biocidal products see our pesticides and biocides guidance.

You may need to deal with the following materials and substances as hazardous/special waste:

  • old or unusable wood preservatives and treatment solutions
  • preservative or treatment containers
  • water collected in sealed sumps serving areas used to store treated timbers.

You must comply with your duty of care responsibilities when dealing with waste.

Your waste responsibilities


You can only use creosote or creosote-related substances to treat wood for industrial or professional purposes - for example, to treat railway sleepers or telegraph poles, for fencing and agricultural purposes and harbours and waterways.

You cannot normally use these substances for other purposes. You must not use wood that has been treated with these substances inside any buildings, in toys or in playgrounds.

You cannot place wood that has been treated with creosote on the market, except for industrial or professional use, or if the wood is subject to an exemption for wood placed on the secondhand market and treated prior to 31 December 2002.

HSE: Woodworking hazards

If you store old creosote, you must dispose of it as hazardous/special waste. Do not pour creosote down a drain, onto land or into streams, rivers or watercourses.

Hazardous/special waste

Wood preservatives and treatments containing chromium and arsenic

You can no longer use copper, chromium, arsenic (CCA) type preservatives to treat timber in the UK.

All wood preserving products containing arsenic and chromium were banned from sale from 1 September 2006, following their review under the BPR review programme.

CCA treated wood already in use is not affected.

If CCA treated wood is imported from outside the EU it can only be used for professional and industrial purposes where users do not come into repeated skin contact with it, for example highway safety fencing.

Other wood treatment products

The BPR review programme is looking at the status of other products and substances used in the UK for preserving wood including creosote, copper and permethrins.

Always check that the product you are using as a wood preservative is approved as this is subject to change.

Health and Safety Executive (HSE): Biocides and pesticides

Storing and handling wood preservatives

Avoid storing large quantities of wood preservatives or other treatments as any leaks from them can pollute surface waters and groundwater. You should store preservatives correctly to prevent them washing into drains. This will protect the environment and could also save you money. You should store wood preservatives and other treatments:

  • in an appropriately sized and designed dedicated store or under cover
  • within suitable secondary containment systems or on a solid base at least 10 metres from a watercourse
  • away from sources of ignition
  • where the risk of damage from vehicle movements or vandalism is low.

You should have a pollution incident response procedure for dealing with spills. Ensure your staff are familiar with the procedure and how to implement it. Report pollution incidents as soon as they happen to the UK wide incident hotline on 0800 80 70 60.

Good practice

Always establish the 'need to treat' before using timber preservatives. There are different levels of treatment for timbers depending on their end use. You may find the following British Standards useful to determine the correct level of treatment:

  • BS 5268-5 1989: Structural use of timber. Code of practice for the preservative treatment of structural timber
  • BS 5589 1989: Code of practice for the preservation of timber

These are available from British Standards Online. You can buy copies of the full standards or view summaries by registering on their website.

British Standards Online

Consider changing your product or structure design to help minimise use of preservatives and coatings where possible. This will help make reuse and recycling easier.

You should try to minimise your use of solvent-based preservatives. Regularly review the preservatives you use and where possible use water-based alternatives.

Train all staff in the safe and efficient handling and use of timber treatments and preservatives.

You should store any treated timbers or wood products on a solid base in areas where run-off will not enter surface water drains or seep into the ground.

Ensure that you always follow any warning labels on treated timber about its use and storage.

Segregate your treated wood waste. This may need to be treated as hazardous/special waste.

Hazardous/special waste

Further information

Wood Protection Association

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