I have just had my carpet cleaned and there is a terrible odour, where is it coming from?

Old pet stains are normally the culprit. It is impossible to remove urine by normal cleaning and while there may be no visible evidence of a stain, the urine oxidises and reacts with carpet to create amino acids which work into the fibres and even into the under floor. When moisture in present, for example after cleaning or in high humidity, the uric acid crystals absorb water and exude an ammonia gas. Professional cleaners have powerful oxidizing agents that can eliminate the source of the odour, which can sometimes involve lifting the carpet and treating the subfloor. It should be noted that if the animal is still in the house it will invariably re-mark it’s territory and the odour will return.  more