Buying a home? Learn about the sewer main 135 rule before you make that offer
- Tim Friedrich
- May 21
- 3 min read
When you’re buying a home, things like roof age and kitchen updates usually steal the spotlight. But one hidden system deserves just as much attention: your sewer main. In fact, there’s a specific plumbing guideline that might save you thousands in future repairs: the 135 Rule.
It’s not well known outside of the plumbing world, but it's worth learning about if you’re buying an older home, especially one with a long driveway or set back from the street.
What is the 135 Rule, and why does it matter?
The 135 Rule is a general plumbing guideline that suggests if a home's sewer main is longer than 135 feet, it needs a cleanout. A cleanout is an access point that allows plumbers to reach and clear out blockages in the sewer line.
Why 135 feet? That’s the distance most standard plumbing equipment can effectively reach from the home's main drain. Once you go past that, removing tree roots, grease buildup, and other obstructions becomes nearly impossible without additional access. If there’s no cleanout, you could be facing some messy and expensive repairs down the road.
How sewer length affects your plumbing
When a sewer main is too long and doesn’t have a cleanout, it puts your entire plumbing system at risk. Over time, natural buildup happens. Tree roots creep in through pipe joints, non-flushable items get stuck, and debris accumulates. If a plumber can’t reach those clogs because the line is too long, there’s not much they can do except recommend excavation, which is disruptive and costly.
And while some problems show up quickly, like a backed-up toilet, others build slowly over time. You might notice gurgling drains, foul odors, or slow-flowing water long before a full-blown sewer backup occurs. The longer the line, the more opportunity for those issues to grow undetected.
What to look for during your home inspection
A traditional home inspection may not include a full sewer line assessment. That’s why it’s smart to request a sewer scope inspection, especially if:
The house was built before 1980
It’s set far back from the street
There are large trees near the sewer path
You don’t see an obvious cleanout in the yard or near the foundation
A sewer scope is a small camera that’s fed into the main line to check for damage, blockages, or excessive length. It can tell you if the sewer main is longer than 135 feet, and whether there’s an accessible cleanout in place.
Can you add a cleanout after buying the house?
Yes, but it comes at a cost. Adding a cleanout often involves digging up part of your yard or driveway to access the sewer line. Depending on the location and local codes, it could be a relatively simple job or a major project.
That’s why it’s better to know before you buy. If the house lacks a cleanout and has a long sewer run, it’s something you’ll want to factor into your offer or negotiate with the seller.
Get peace of mind before you sign
Buying a home is a big investment, and sewer issues can turn into big headaches if you’re not prepared. At Allied Reddi-Rooter, we give Cincinnati home buyers peace of mind by offering sewer scope inspections and honest advice.
The 135 Rule might sound like a minor detail, but when it comes to your sewer main, it’s a detail that can make all the difference. Know what you’re getting into so you can enjoy your new home with fewer surprises and fewer clogs.
