question on cast iron piping

[Cindy Joseph]

hello I am new to this and  looking at a property with cast iron pipes under the house built in 1957. There are no leaks. Was wondering how urgent is it to change to pvc? Also what would the total cost of replacing pvc look like? I understand that you have to tear up the floors to do this.  Its a a 2/1 duplex about 850 square feet each side. 

Are pipe liners any good? Ive heard mixed reviews on this. 

[Bruce Woodruff]

Cast Iron has a life expectancy of 50 - 60 years. It is not a question of if it will fail, but how soon....

As a longtime GC and former Home Inspector, I've seen many of these systems...hundreds. And they all get replaced.  Average cost is $7-10k from under house to the city sewer main. Replace it all except for the vertical drops.

So it depends on how long you intend to keep this house. If long term, you might as well bite the bullet and do it while the house is empty and being remodeled anyway. If it's a quick flip, then just disclose it and let the next owner deal with it....