PET bottles: caps, labels and colours

Caps: usually on

Bottle caps are normally made of a different plastic, polypropylene or HDPE. At a recycling plant the bottles are ground into flakes and washed. The flakes then go through a water bath where PET sinks and the cap plastic floats, so the two come apart on their own.

Kent State University's sustainability office tells people to keep caps on, for two reasons: caps are recyclable too, and an easier rule gets more people to recycle.

The older advice in Australia was to leave caps off. Bottles still holding liquid were being rejected or causing contamination, and caps could pop off while bottles were baled under compression. Today the Australasian Recycling Label says "Crush Bottle and Replace Cap", which makes it less likely the bottle still holds liquid and keeps the cap from popping off.

It is not settled everywhere. In the UK, some plastics reprocessors prefer householders to remove caps, because it is then easier to separate the two parts. Ask whoever collects your bottles which they prefer.

Labels: mostly a sorting-plant problem

Design guidelines from European recyclers flag sleeves and labels made of denser plastics such as PVC, as well as PET labels and paper labels that are not wet-strength, as contaminants in the PET stream. A PVC sleeve can also hide the bottle from the near-infrared scanners that identify plastic, so the whole bottle gets sorted wrongly.

Those scanners are in large optical sorting plants. For a bottle you hand to a collector, the practical advice is simple: if a shrink sleeve tears off easily, take it off, and do not scrape off paper labels.

Colour: clear is easiest

WRAP, the UK's recycling charity, said in 2019 that using clear PET rather than coloured plastic increases the chance a pack gets recycled, because the end market for clear PET is stronger. RecyClass grades light transparent colours as fully compatible with recycling, dark transparent colours as limited, and opaque, fluorescent or metallic colours as not compatible.

Plants usually split coloured bottles into separate colour streams. A green or brown bottle is still recyclable, but it gives the recycler fewer ways to use it.

A routine that works

• Empty the bottle and rinse it once.
• Crush it flat, then put the cap back on.
• Keep clear bottles together and coloured ones together.
• Keep out other plastics, caps from other products, glass and cans.
• Keep the bag dry and away from food waste.

Selling PET in Dehradun

We collect PET bottles from homes and businesses in Dehradun, weigh them at your door and pay ₹18 per kg. Rates last updated 26 October 2026.