Sewer Line (lateral) Replacement

We are replacing our sewer line tomorrow from the house until the street. We have 4 inch cast iron under our foundation and the cast iron leaves the foundation and turns into a clay pipe 3 feet from the house foundation. This then connects to 6 inch clay pipe all the way to the city sewer (70 ft).

The contractor told me he would replace the clay with 4 inch PVC (schedule 40) since that is the size of the cast iron pipe and just tie it into the proper size at the street

However, shouldnt he replace the 6 inch clay with 6 inch PVC or does it not matter? I would assume that he should replace it with a similar sized pipe

Please let me know ASAP your thoughts as he is scheduled tomorrow.
Thanks,
Zev.

 

4" is pretty much the standard size.

If it helps, think of it this way: You've got 4" coming out from under the house, so two inches of the old clay pipe was unused except during backups and by replacing with properly installed PVC, you're pretty much eliminating any potential for problems.

After all, a 4" pipe can't discharge 6" of waste.
And again, 4" is generally the norm.

 

Not a pro and I don't know what is the norm, but were it me I would use schedule 80 pvc.

 

Sch 40 will be fine. 4" is better than 6". With six inch, the water will slow down, and drop out the solids. The velocity of the water will slow down too much.
It would also be a good idea to place a clean-out every 25 to 30 feet. Just in case.


Travis

 

Thanks. We did sch 40 4" PVC with 2 cleanouts.