If you are buying a home built prior to 1970 it will more than likely have cast iron waste lines. Cast iron pipes often have internal corrosion that results in leaking and clogging, or cracks that cause leaking within the units. Soil PH and corrosive chemicals and detergents put down the drains can cause the pipes to fail prematurely, Tree roots are another condition that can damage these pipes.
Be sure to ask the seller about any past or current drainage problems. If the seller tells you the cast iron has been replaced from the building to the street…keep in mind there’s still cast iron within the slab and this is where problems can still occur.
Having an in-line camera inspection performed on the property during your due diligence period can save you tens of thousand of dollars in costly repairs and lost revenue. Also during your property inspection, the inspector should flow lots of water and stress the system to ensure proper drainage.
Detecting failing waste lines during your due diligence is the best outcome. And having the proper inspections is your best defense.