Can old carpet just go out with the regular garbage in Hamilton?

Only within limits. The City of Hamilton collects carpet, underpad and linoleum at the curb as bulk items when each piece is rolled and tied into a bundle no longer than 1.2 metres and under 90 kilograms, with a maximum of eight items per booking, and construction and renovation material is on the city's refused list, so a full tear-out from a renovation cannot simply go out with a routine bulk pickup. We treat removal and disposal as a separate, priced line on the quote for exactly this reason, so you know before the job starts whether it is handled for you or left for a bulk booking.