| Approach | Verdict |
|---|---|
| Enzyme treatment reaching full contamination depth | Works — the standard fix |
| Extraction plus enzyme on fresh surface accidents | Works, often completely |
| Subfloor sealing after treatment | Works for deep contamination |
| Pad and carpet replacement | Works — sometimes the cheapest real answer |
| Store-bought spray on an old deep stain | Rarely — usually can't reach it |
| Steam cleaning alone | No — heat can set proteins |
| Fragrance, powders, deodorising sprays | No — masks it for days |
| Vinegar or baking soda on old urine | No — doesn't touch the salts |
Why humidity brings the smell back
Urine dries into crystalline salts inside the carpet, pad, and sometimes the subfloor. Those salts are hygroscopic, meaning they attract water from the air. On a humid day they take on moisture, become active again, and release the odour compounds. That's why a spot can seem fine all winter and announce itself in July — and why any treatment that only addressed the surface will keep failing.
The visible stain is not the size of the problem
Urine spreads outward and downward through carpet, pad, and into the subfloor. Under UV light, a spot the size of a coaster on the surface is regularly the size of a dinner plate underneath. Treating only what you can see is the single most common reason DIY attempts fail.
When replacement is the honest answer
If urine has repeatedly soaked the same area over months or years, the pad has absorbed volume that treatment can't fully flush, and the subfloor may be contaminated. At that point replacing pad and affected carpet — and sealing the subfloor — often costs less than repeated treatments that each improve things partially. A company unwilling to tell you that is selling treatments, not solutions.
What to do the moment it happens
Blot, don't scrub — scrubbing drives it deeper and damages the fibre. Press with white towels until they come up nearly dry, rinse lightly with cool water, blot again. Skip the coloured cleaner and skip heat. Then call sooner rather than later; fresh is dramatically easier than set.