House is built on a concrete slab. HVAC is in a centrally located closet. AC drain line is 3/4" PVC going into the slab. After 40 years of use I finally had a drain blockage. HVAC tech said the line drains into the sewer line and it was probably blocked there and to use pressure to blow the blockage out. A plumber aquaintance said the line drains into a dry well under the slab and to use a shop vac suction to remove the algae blockage. Who's probably right?
I tend to doubt drainage into a sewer line because of the possibility of sewer gas/fumes getting into the house but at the same time if it is, I hate to hook a shop vac to a line and suck sewerage into a 3/4" line causing a bigger blockage.
Red