A Mt. Lebanon seller once had a signed agreement of sale at $724,000, no time-of-the-essence clause, and a buyer who missed the closing date by eleven days. The seller assumed breach, relisted the house, and accepted a second offer at $738,000 without properly terminating the first contract. The case ended up in the hands of a Pittsburgh real estate attorney, who used it as a cautionary example of what happens when routine closing friction gets mistaken for bad faith. Among the culprits she named for pushing closings sideways: title backlogs, lender conditions, tax certifications and dye tests.
That last one surprises people who have never sold a house in Mt. Lebanon before. It is not a home inspection. It is not a termite letter. It is a municipal requirement that a licensed plumber pour fluorescent dye down your downspouts and watch to see if it shows up in the sanitary sewer, and it has been baked into the sale of every improved property in the municipality since 2004. Most sellers hear about it for the first time from their agent or their title company, usually a few weeks before they had planned to close.
What the test actually checks
Mt. Lebanon calls it a dye test, and the mechanics are almost quaint. A plumber registered and licensed in Allegheny County drops powdered dye into a downspout, area drain, or interior sump, flushes it through, and watches downstream. If the water shows up bright green in the sanitary sewer, that drain is illegally connected. The municipality tests at every downspout, at driveway and area drains, at negative-slope driveways with fresh-air vents, at roof drains on flat roofs where the rain leader runs inside the structure, and at interior French drains or sumps.
The reason this exists has nothing to do with your home's condition and everything to do with the regional sewer system's capacity. Sanitary sewers are built to carry wastewater from showers, dishwashers, and toilets. Storm sewers are built to carry rain off roofs and driveways. When a builder decades ago ran a downspout into the sanitary line instead of the storm line, that mistake now shows up as extra flow every time it rains, and Mt. Lebanon has been chasing those connections down since the 1980s. The municipality's first organized round of dye testing started in 1987 in Mission Hills, Central Square, parts of Sunset Hills, Main Entrance Drive, Roycroft Avenue, and Hoodridge Drive. By 1996, roughly 9,000 homes had been tested, and about one in five failed. By the early 2000s, every house in the municipality had been through it at least once. In 2004, responding to a federal mandate, the commission converted that one-time sweep into a permanent condition of sale: Ordinance No. 3099.
The part that catches sellers off guard
Here is the mechanism that actually matters if you are planning to sell. The ordinance does not require you to fix a violation before you can accept an offer. It requires you to fix it, or make formal arrangements to fix it, before you can close. That distinction sounds small until you are the one holding a signed agreement and a failed test three weeks out.
Mt. Lebanon gives you two paths. The clean one is standard Evidence of Compliance: submit the completed, passing test along with a $50 fee at least 10 business days before closing, and the Public Works Department forwards a letter of compliance to the Finance Office, where it gets bundled with your municipal claims letter and tax certification. Skip the dye test and you don't get those documents either, which means you don't close, regardless of how the rest of the transaction is going.
The second path exists for when the first one doesn't work in time, whether because of weather, scheduling, or a failed test that needs repair. That's Interim Evidence of Compliance, and it comes with real strings attached. You need to file at least 14 business days before closing. You need to post a certified check for $200 as security. And you need a signed, written agreement with your buyer in which the purchaser agrees to conduct the dye test and correct, at the purchaser's own expense, whatever the test finds. The ordinance does leave the door open for the buyer to seek reimbursement from the seller afterward, but the obligation to actually get the work done shifts to whoever now owns the house. If nobody follows through, that interim approval expires after six months and the security gets forfeited.
So the real risk in Mt. Lebanon isn't that your house fails a dye test. Plenty do. The risk is timing it late enough that your only option is transferring an open plumbing repair to your buyer as a condition of closing, which is a very different conversation than fixing it quietly before the house ever hits the market.
The three-year clock you might already be inside
One detail that rarely makes it into listing conversations: a passed dye test is only good for three years. If you sold a different Mt. Lebanon property, refinanced with a required test, or bought your current home anytime in the last three years, you may already be sitting on a valid certificate, or you may be closer to its expiration than you realize. Refinancing alone doesn't trigger the requirement, so if your last test was tied to a mortgage refi rather than a sale, you likely don't have one on file at all. Either way, it's worth confirming with the municipality's Public Works Department before you set a listing date, not after.
What this actually costs you in planning
| Path | Lead time before closing | Upfront cost | Who's on the hook if it fails |
|---|---|---|---|
| Standard Evidence of Compliance | 10 business days minimum | $50 filing fee | Seller corrects before closing |
| Interim Evidence of Compliance | 14 business days minimum | $200 certified check security | Buyer agrees in writing to correct, with a right to seek reimbursement |
The gap between those two numbers, four business days, is the margin most sellers don't build into their timeline. A test scheduled with plenty of runway rarely becomes a negotiating problem. A test scheduled to squeeze in right at the ten-day mark, only to fail, forces you into the interim track with a buyer who now has leverage they didn't have a week earlier.
This is also why a failed test can shrink an offer even when it gets caught early. Once a buyer knows the house needs a plumbing correction to satisfy the municipality, that repair becomes part of the negotiation whether or not it was ever part of the inspection contingency.
Mt. Lebanon isn't unusual in requiring this. Similar lateral or dye testing ordinances exist across the South Hills and beyond, including Upper St. Clair, Brentwood, and South Fayette. What makes Mt. Lebanon worth understanding specifically is how tightly the ordinance ties the test to your actual closing documents. You cannot get your tax certification letter until this is resolved, which means it is never really optional and never really separable from the rest of your closing checklist.
Frequently Asked Questions
Do I need a dye test if I'm just refinancing? No. The point-of-sale requirement applies to sales and conveyances, not refinances.
How long is a passed test valid? Three years from the date it was performed.
What if my house fails? The plumber reports the failure and the reason to the Inspection Department, and corrective measures need approval before compliance is issued. If there isn't time to fix it before your closing date, the interim compliance path lets the sale proceed with the repair obligation formally assigned, usually to the buyer, in writing.
Who actually performs the test? A plumber registered and licensed in Allegheny County. The municipality itself does not schedule or perform the test.
Is this specific to Mt. Lebanon? No. It's common across a number of Allegheny County municipalities, though the exact fees, timelines, and paperwork vary by community.
If you're planning to sell in Mt. Lebanon, the smartest move is finding out where you stand on this before your listing goes live, not after an offer is already on the table. That's the kind of groundwork The Burgh Luxury handles as a matter of course for sellers across the South Hills. Let's connect and get your timeline mapped out properly, before the clock starts working against you instead of for you.
