Recycling of metals, especially aluminium, proved to be very important for impact categories such as resource depletion and hu¬man toxicity via water. The cities with the largest metal content have the largest avoided impact, especially for the human toxicity category, and increased source-separation of metals is important in all cities for resource depletion, human toxicity via water, and even for global warming. The human toxicity via water category is very sensitive to changes in metal content, especially aluminium con¬tent. In Norway glass and metals are collected together and sepa¬rated in a centralised plant serving the entire country. The actual fractions of glass and metal, and of different types of metal, are re¬ported at a national level only. This leaves large uncertainties in assessments at a municipality or settlement level, which will affect the results of an accounting LCA where we have an estimated source-separation ratio. However, uncertainty in waste composi¬tion concerning metals is of little importance if the source-sepa-rated amounts are known.