BSI PAS 100: producing quality compost

The Publicly Available Specification 100 (BSI PAS 100) for composted materials was sponsored by WRAP and developed in conjunction with the Association for Organics Recycling (AFOR).

BSI PAS 100 is part of WRAP's ongoing work to develop a dynamic market for quality compost products. WRAP has worked with AFOR and the Growing Media Association to develop compost specifications and guidelines tailored to the industries.

It will improve confidence in composted materials among end users, specifiers and blenders, and will help producers differentiate products that are safe, reliable and high performance.

The Composting Association has adopted BSI PAS 100 as the specification that composted materials must meet in order to achieve the independently verified Composting Association accreditation and use of TCA logo. Guidelines have been drafted to use as an easy tool when drawing up contracts for operation of large scale, licensed composting facilities.

BSI PAS 100 - Compost specification


The specification was updated in 2011 following a period of intensive stakeholder review and consultation, building on its predecessor by including a number of improvements and efficiencies.

Key improvements included:

  • new upper limits for some test parameters
  • a new test method for E.Coli.  
  • the updated BSI PAS 100 does not allow the composting of sewage sludge or its derivatives
  • allows the addition of digestates from anaerobic and aerobic digestion processes
  • references to new legislation, guidelines and scientific reports
  • re-formatted to make it easier to use

Specifying conformance to BSI PAS 100

These guidelines have been drafted as an easy tool to be used when drawing up contracts for the operation of large scale, licensed composting facilities. They will help to properly refer to BSI PAS 100 in Local Authority Waste Management Contracts. Specifying Conformance to BSI PAS 100 in Composting Service Contracts – Sample clause (27 kb) 

Complaints procedure

If you have purchased PAS100 certified compost, and you don’t believe it to meet the required standard, then please visit the AFOR website for information on how to register your feedback.