Replace, Line, or Hope? How We Decide on a Big Sewer Repair

A duplex we manage had a sewer problem recently. Nothing dramatic: it backed up a bit into the lower unit. But it was enough to find out what was really going on under the floor.

The cause was one of the most common in our area: tree roots. The line from the foundation out to the city main had been replaced with PVC in 2022. The line inside the house, though, was still the original cast iron, and that's where the roots were getting in. It wasn't our tree, so keeping the roots away wasn't a realistic option.

We ended up with three quotes, three very different price tags, and a decision every rental owner faces sooner or later in some form. Here's how we thought it through.

Option 1: Replace It

The "do it right" answer was replacing the cast iron. The quote was $15,000.

That number didn't include the things that come with it. Concrete had to come out in the lower unit. Flooring replacement would add roughly another $5,000. And the tenant would need to be temporarily relocated while the work was done.

Relocation is the part owners tend to underestimate. It isn't just a hotel bill. It can mean packing, moving, and storing a household's belongings, then moving everything back. On a job like this, the real cost is the quote plus everything the quote leaves out.

Option 2: Line It (While You Still Can)

The second quote was $5,000 to insert a PVC liner inside the existing cast iron. Both households would need a hotel for two or three days, but no concrete comes up and no floors get replaced.

Here's the catch, and it's why this option has a deadline. A liner works well when the pipe is still intact. Once a line collapses or develops a major belly (a sagging section where waste settles), lining may no longer be possible. We didn't have a collapse or a belly. Yet.

That makes the liner a preventive repair. It's an option today. It may not be one after the line fails.

Option 3: Clean It Yearly and Hope

The cheapest option this year is clearing the roots out of the cast iron once a year and hoping for the best. That might buy a year. It might buy twenty. There's no way to know.

"Hope" isn't automatically the wrong answer. On some properties, with some budgets, it's a reasonable call for a while. But it's worth being honest about what it is. You're betting the line holds. If it doesn't, you've lost the cheaper fix, and you're back to Option 1 on an emergency timeline, probably in the middle of a backup.

Run the Quotes Against the Rent

The property is a Class C duplex that grosses $1,800 a month. That's the number that puts every quote in perspective.

Replace: $15,000 plus roughly $5,000 in flooring is $20,000, before a single relocation cost. That's more than 11 months of the whole building's gross rent.

Line: $5,000 is a little under three months of gross rent, plus two or three hotel nights for two households.

Clean and hope: the cheapest option every single year, right up until the year it isn't.

We leaned toward the liner, so the building gets another 20 years out of that line instead of another year of crossed fingers.

Water Never Shows Up at a Convenient Time

Sewer lines aren't the only place this plays out. At another property, we remodeled a downstairs unit. It was a nice remodel, it got max market rent, and it leased within 24 hours of listing.

On the new tenant's first day, after a torrential five-hour downpour, they reported water in the unit. We'd managed that unit for years and never had a water issue. It looked like it was coming through the wall.

The fix meant digging up the front yard, installing moisture barriers, and adding a sump pump. The cost came to about 10 months of that unit's gross rent.

Nobody budgets for a surprise like that. But having a process for big repairs turns a gut punch into a decision instead of a panic.

How We Approach a Big Repair

None of this is exotic. It's the same process every time.

Get the real diagnosis first. Know what's actually failing, and why, before anyone prices a fix.

Get more than one option. The right answer isn't always the cheapest or the most expensive. Three real quotes gave us three real choices.

Price the whole job. Flooring, access, hotel nights, relocation, and lost rent all count, not just the contractor's line item.

Measure it against the property's income. A repair that makes sense on one building can be a bad investment on another. We've written about how the best vendors read the room on finishes. Capital repairs deserve the same judgment.

Ask what waiting costs. Some repairs get more expensive with time. Some options disappear entirely.

Stay inside the budget, and ask when we can't. We keep strict repair budgets, with an owner-approval step before we go past them. Owners who keep capital-expense funds set aside with us make it easier to move quickly when timing matters.

Why This Matters

Most owners don't lose money on a rental because of one bad repair. They lose it on decisions made in a hurry: the cheap patch that fails at the worst possible time, or the expensive fix that never pencils out. We've shared what real maintenance calls actually cost, and the biggest ones are where judgment matters most.

Rentals are not for the weak. They're a lot easier with a manager who treats your property like an investment, not just a work order.

Facing a big repair and not sure which way to go?

We'll walk through the real numbers with you, including the ones the quote leaves out. Get a free rental analysis to see what your property should actually be earning. Let's talk. Blair Allen Property Management serves owners across South Dakota and Montana.

Chris Twiggs
President, Blair Allen Property Management
📞 605-545-1218
✉️ chris@blairallen.com