Does rubbish have to be in black bags?

No, rubbish does not have to be in black bags: the colour is a convention, not a rule. What matters is that the bag is strong enough not to split, is tied, and goes into the right collection. Households follow their council's instructions, which vary by borough. A business cannot use its own black bags for a kerbside collection at all: commercial waste has to go in a wheelie bin or in the printed sacks supplied by a registered carrier, so the driver knows which bags are paid for and which stream they belong to. A black bag left on the pavement by a business counts as fly-tipping and can draw a fixed penalty of up to £1,000.