We are buying a house. When we had the sewer line scoped under the basement, we saw that the lateral line reduces from 4in pvc to 3in pvc. Is this a big deal that we have to have fixed before completing the sale or is it not a huge deal?

House has 2 bathrooms if that makes a difference.

What's the lateral line running to?

Was the drain line recently re-done? If not, and it's been operating that way, I'm not sure I would mess with something that's working. And if I was the seller and you tried to demand that, I'd tell you no.

Horizontal or vertical

It is a horizontal sewer line. The house is 100 years old. The original sewer line from the house was probably iron or clay.

My guess is this was a fix to get past a damaged part of the original 4" line. I imagine that they could not connect the new 4" PVC to the damaged line and instead put a 4 to 3 reducer and 3 inch PVC to get past all the damaged sections of the original pipe.

Thanks for the responses by the way.

Without knowing the layout of the lines, it's difficult to answer. I think I would inquire about any recent issues with their sanitary lines and if none either don't worry about it or use it as a negotiation on price.

Check to see if permits were pulled for the work.

Are you saying that the pipe reduces in size in the direction of flow? You have a 4" pipe that dumps into a 3" pipe? Is there standing water in the line?

AggieT said:

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Are you saying that the pipe reduces in size in the direction of flow? You have a 4" pipe that dumps into a 3" pipe? Is there standing water in the line?

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Yes in direction of flow. Yes 4" to 3". I saw a small amount of water, but I'm not sure how long the inspector waited before taking the picture. I know they put water in to test, and he didn't mention standing water. I know this is not ideal. I'm just trying to get an idea of how "not ideal" it is.

The previous owners did not mention it and may not even have known about it. They are military and only lived there 2 years before being transferred. We are in negotiations and have asked them to fix it, but if they won't, I want to estimate the risk ($) we are taking on if we go ahead with the purchase.

Thanks again for taking the time to reply.

Sounds bass ackwards.

I suppose it could cause a potential stoppage at the transition area if someone gets crazy with toilet paper

I would assume ~ 1/2 inch of wastewater would always be standing on the 4 inch side at the bottom of the pipe. Have never seen this in the field but maybe a plumber will chime in on it.

Thank you all for the reply's. The seller agreed to fix the issue. Unfortunately, there was a large amount of tuck-pointing that they would not agree to so, the house search continues.