There isn’t one universal weight limit for bags used in urban trash bins. It really depends on the bin type, the collection system, and your local council or waste authority. A public litter bin, for example, usually just uses a bag as a liner, so the bag should be light enough to lift safely and not tear—often around 10 kg or less is a sensible practical limit.
For larger wheelie bins used in residential or commercial areas, what matters most is the total weight of the bin, not just the bag. Many 240L bins are designed for roughly 100–150 kg total, but collection crews may set lower safe limits. As a general rule, individual waste bags should stay around 10–15 kg for easy manual handling, and I would avoid making a single bag heavier than about 20 kg. Overloaded bags split easily, and they can also make the bin too heavy for the lifting mechanism.
If you’re using a shared urban trash bin, check any sticker or building notice first, and ask your local waste department if you’re unsure. The safest approach is simple: keep bags manageable, double-bag sharp or messy waste, and never fill a bin beyond its stated weight limit.