Check the bill and the yard. Borough homes pay a sewer bill and have no tank; township homes have a septic tank, usually with access lids in the yard, and no sewer line on any bill. The plumber cares because the systems share almost nothing: a borough slowdown is investigated with a camera in a lateral, a township slowdown is investigated at the tank and field, and sending the wrong visit is the most common wasted money in this postal area. If you genuinely do not know, say so on the first call; determining it is a five minute part of the visit, and it decides everything after it.
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