An old urine stain that's been walked over and vacuumed a dozen times has usually been treated on the surface, while the actual smell sits down in the fibres and the backing where routine cleaning never reaches.

This is an enzymatic cleaner built to penetrate deep into carpet fabric rather than just lift a surface stain, aimed at severe, established urine marks and their smell. Simple Solution's method is to saturate the area and the surrounding region, covering twice the size of the mess, let it sit for 10 minutes, blot with a colour-safe cloth, then allow 24 to 48 hours to dry fully before vacuuming. It's Woolsafe and Clean Seal approved, and works on carpets, upholstery, hard surfaces, cement and other water-safe surfaces. It's a 1-litre bottle.

• Enzymatic formula, penetrates deep into carpet fabric
• Targets severe, established urine stains and odours
• Woolsafe and Clean Seal approved
• For carpets, upholstery, hard surfaces and cement
• Saturate, wait 10 minutes, blot, dry 24-48 hours
• 1-litre bottle

Test before you commit. Simple Solution ask for a test on an inconspicuous area first and say it's not suitable for leather, which is easy to skip when a stain feels urgent — but a colourfastness test takes a minute and a ruined patch of carpet takes a lot longer to live with.

Who it's for: owners dealing with an old, established urine problem rather than a fresh accident — the kind that's been cleaned before and is still smelling — on carpet, upholstery or a hard surface.