How pad contamination happens
Carpet pad is open-cell foam or bonded rebond designed to compress and recover, which makes it extremely absorbent. Urine passes through the carpet backing in seconds and the pad soaks it up like a sponge, spreading laterally well beyond the visible mark. Repeat accidents in the same place saturate it completely. The carpet above can be cleaned to a genuinely good standard while the pad underneath continues to hold the entire deposit.