Sack Race: Compostable, Recycled and 'Degradable' Liners at the Kerbside

The bin-liner aisle has become a philosophy exam with a drawstring. In 2026 you can buy sacks labelled compostable, recycled, degradable, biodegradable, plant-based and 'eco'. Some are sized for food caddies, some for general waste, and at least one will make your council's collection crew sigh. The labels look like they answer the question. Mostly they just move it.

Start with the stream, not the sack

Before you compare materials, work out where the bag is going. A liner only earns its label if it matches the collection it lands in. A compostable caddy liner in a general waste wheelie bin is not doing much composting. A recycled polythene sack stuffed with tins and cardboard is not recycling either; it is contamination with handles.

In practice, most UK homes have three possible destinations: a food waste caddy, a general waste bin, or a recycling container. The liner needs to suit the first two. Recycling containers generally do not want liners at all, even ones made from recycled plastic. Loose is usually the rule.

What 'compostable' actually promises

Compostable usually means the bag is certified to a standard such as EN 13432, which is about industrial composting conditions. That is a real promise, but it is a promise made to a commercial composting site, not to the muddy corner of your garden. It does not mean the bag will vanish in a home heap, and it certainly does not mean it can go in mixed recycling.

Some councils accept compostable caddy liners in food waste collections. Others ask residents to use no liner at all, or only the bags they supply. This is not consistency for its own sake; it depends on what the council's processing plant can handle. Check your local authority's waste A-Z before buying a box of 200. A bag that says 'compostable' in large green letters can still be the wrong bag for your kerbside scheme.

Home compostable is a different claim again. It sounds friendlier, and for a garden heap it may be useful. But your council's food waste service may not accept home-compostable bags, because its process is built around industrial composting or anaerobic digestion. The logo on the box is not a passport to every bin.

Recycled: the quiet workhorse

Recycled bin liners are usually made from post-consumer or post-industrial polythene. They are not compostable, and they do not pretend to be. They belong in general waste. Their benefit is that they use existing plastic rather than virgin material, and they tend to be strong, stretchy and good at holding a wet yoghurt pot without splitting on the way to the wheelie bin.

The trap is assuming that a recycled liner makes the contents recyclable. It does not. If you fill a recycled sack with paper, cans and plastic bottles and put it in the recycling bin, the sack itself is likely to be removed as contamination. Keep recyclables loose, and save the liner for the stuff that genuinely has nowhere else to go.

'Degradable' is not a finish line

Degradable is the vaguest word in the aisle. It often describes plastic designed to fragment into smaller pieces. Those pieces are still plastic. They do not feed soil, and they can contaminate compost and recycling streams. If a bag says degradable but does not carry a recognised compostability certification, treat it as general waste and ask whether you need it at all.

Biodegradable is not much better on its own. Almost everything biodegrades eventually, given enough time and the right conditions. A landfill is not a compost heap. A hedge is not a compost heap. The useful question is not 'will it break down?' but 'will it break down in the system my council actually uses?' Most vague degradable sacks fail that test.

The caddy test: strength, sweat and the tie

Compostable liners can go soft when they sit in a wet caddy. They are often thinner than polythene, and a heavy potato peel session can test the seams. Choose the right size, do not overfill, and empty the caddy often. A liner that tears on the kitchen floor has not saved anything.

Recycled polythene is the tougher option for general waste. It copes with sharp edges and damp rubbish, and it ties more reliably. Paper liners breathe and can be useful for dry food scraps, but they are flimsy when wet and may need changing more often. Double-bagging is usually a sign that the liner is wrong for the job, not a sign of extra care.

Lining a caddy with newspaper or a used paper bag is a free alternative, but only where your council accepts it. Some collection crews will take it; others will leave it behind. The same goes for compostable bags that are not on the council's approved list.

The money maths

Price per liner is misleading. Compare price per litre, and then factor in how often one splits. Compostable caddy liners often cost more per bag than basic recycled polythene, but they are doing a different job. If your council accepts them and they help you use the food waste collection, the comparison is not like for like. Paper liners sit somewhere between, though they can need changing more often.

The cheapest low-waste option may be no liner at all. Rinse the caddy, empty it directly into the kerbside food bin, use a bowl for prep scraps, or keep a small tub in the freezer for smelly bits. That only works if your council allows it and you can keep the bin clean. For general waste, a liner helps keep the wheelie bin fresher, but dry non-recyclable waste may not need a fresh sack every time.

When no liner is the right liner

Some councils explicitly ask for no liner in food caddies. Others require bags for hygiene. Follow the local rule. At home, a rinsed caddy and a layer of newspaper can cut liner use dramatically. A dedicated freezer tub for meat scraps and cooked food can stop smells before they start. None of this is glamorous, but it is often the lowest-waste choice available.

Do not let 'zero waste' become 'zero hygiene'. If skipping the liner means the caddy never gets washed, you have traded a small plastic saving for a bigger food waste problem. The aim is to use the right bag, or no bag, for the collection you actually have.

A 2026 label-check routine

1. Find your council's food waste rules before you buy anything.
2. Match the bag to the stream: caddy, general waste or neither.
3. Look for EN 13432 or a home compostable certification only if it is relevant to your council.
4. Treat vague 'degradable' claims with suspicion.
5. Buy the smallest useful size so half a box does not go stale in the cupboard.
6. Try a week without a liner in one bin and see what actually happens.

The best bin liner is the one you did not need, followed closely by one that ends up in the right place. The rest is just packaging with a good vocabulary.