Can you use bleach on carpet?

The question usually comes up for one of two reasons: a stain that will not shift, or a spillage that needs disinfecting. They have different answers and it is worth separating them.

As a stain remover

Chlorine bleach removes colour. On a carpet it removes the carpet's colour at least as readily as the stain's, and the pale patch it leaves cannot be dyed back or cut out and replaced without a visible repair. Infection control guidance states plainly that chlorine based disinfectants should not be used on soft furnishings, untreated wood or carpets because they cause whitening.

The polypropylene exception

Polypropylene is dyed while the fibre is still molten, so the colour is part of the strand rather than applied to its surface. Carpet manufacturers who allow bleach at all allow it on that fibre, and specify a dilution of one part bleach to four parts water. Some ranges are sold as bleach cleanable on that basis.

The difficulty is knowing. Nylon and polyester carpet look similar underfoot and are dyed conventionally, so bleach strips them. Unless the paperwork, the retailer or the manufacturer confirms solution dyed polypropylene, the safe assumption is that this exception does not apply to your floor.

As a disinfectant after a spillage

The same guidance that uses household bleach at one part in ten for blood on a hard surface excludes it on carpet, and directs that carpet is dealt with instead using a neutral detergent and warm water, or a carpet shampoo machine, or a steam cleaner. Bear in mind that heat sets a protein mark, so if the spillage was blood, get the mark out cold before anything warm goes near it.