The most important reason is worker safety.  When caps are left on bottles (which are filled with air), then are driven over by heavy equipment, or compressed in the baler, they basically become projectiles that can cause serious injury to staff at the plant.

The second reason is from a marketing perspective. Most bottle caps have an interior liner at the top which is of a different plastic type than the cap itself. This mix of plastics and the likelihood of contamination from food or beverage residue make the cap less desirable in the mixed plastic market.

As with all our recyclables, our programs try to ensure we obtain the highest market value for our materials.  Another example of this is sorting paper separate and protecting it from the weather in plastic bags.

The third reason is one of practicality. Trying to pick and sort little bottle caps from the processing line from amoung all the other material would be more than challenging and not worth the effort of the extra resources needed to try.

Have you ever wanted to see inside HRM's Recycling or Compost Facilities? Take a virtual tour of HRM's Recycling and Compost Facilities on YouTube to find out what happens when material leaves the curb.