How to Locate a Lost Sewer

A quick visit to city hall and a few facts and figures are all you need to locate pipes accurately – so that you can provide a repair estimate with confidence

A contractor was having trouble locating a residential sewer line. He had a new inspection camera and one of the best locators available, but he couldn’t find the pipe.

What he needed to know was where the sewer exited the customer’s property. He knew where the pipe exited the house, but he could not determine where his repair would terminate. The line was totally blocked with roots, and he couldn’t get his equipment far enough down line.

The line exited the house at an angle, so he was nervous about bidding the job. He didn’t know if the line was 30, 40 or 50 feet long. He wasn’t sure if it traveled under a new concrete driveway.

When estimating, you need to know exactly how long the line is, how deep it is, where your repair begins, where it ends, and if there are any obstacles to your trenching. Without knowing these values, you’re guessing.

You can try to bid this project on time and materials, but in today’s world where most of your competition bids on a flat-rate basis, T&M is a very tough sell. So he called me to help him find the property line connection. It is denoted in the accompanying illustration by a question mark. That’s where a sewer changes to a lateral. I arrived at the site and assured him that this was not a problem.

An easy way

There is a very simple way to find a lost sewer – a line that is either too deep for your locator’s capabilities or that is too plugged with obstructions so that you can’t send your camera or locating transmitter to where it needs to go. He was amazed when I was able to get the information by simply making a phone call. Let me tell you how I did it.

Many municipalities will give you this information over the phone. For those that will not, you must go to the department of building and safety and visit the help counter for the engineering department. Tell them you need a lateral location.

All they need is the job address. They then go to the map archive room, and a few minutes later, they reappear with a sewer map of that neighborhood. The lateral (also called side sewer) is the section of sewer that is installed when the main sewer is put in. It travels from the center of the street up to the edge of the property. It is then capped off until a developer builds a house on that lot and connects the house sewer to it.

This stub is documented with the engineering department. It is located directly below the property line, which in my area means directly below the edge of the city sidewalk closest to the house. Laterals are always under public property or within a city easement that travels through private property. If you are converting from a septic system to city sewer, this stub is where you connect.

The counter person will provide you with a few measurements, which are distances from manholes. The main sewer is the public sewer that travels down the center of the street.

By the way, main sewers always run in a straight line from one manhole to the next – there is never a bend or a turn. Changes of direction are achieved inside the manholes. If the street curves, the pipe does not. If you draw a string from one manhole to the next, the sewer main is directly below that string. If mains had bends, they could not be cleaned by the city’s rodding machines. Rodding machines do not make turns. They must follow a straight line.

Taking measurements

So, I made a phone call to the engineering department and was given a few measurements over the phone (See illustration.) The measurements I was given were:

• Upper manhole: East 2+50

• Lower manhole: West 5+50

• Station number: 3+50

• Length of lateral: 25 feet

• Depth of property line connection: 5 feet

The entire conversation lasted about three minutes. Let’s define some terms. Sewage flows from the upper manhole to the lower manhole. The elevation of the bottom of the upper manhole is higher than the elevation of the bottom of the lower manhole. You can verify the direction of flow by lifting a manhole cover. The flow is always from upper to lower.

The station is where your lateral line (usually 6-inch clay or PVC) connects to the street main in the street. The station is always between your upper and lower manholes. Don’t let the plus signs (+) confuse you – ignore them. Municipalities use the plus sign instead of saying the word “hundred.” It is engineering short-hand. 2+50 means 250 feet. The rest is a cinch.

I walked to the center of the street in front of the house, looked east and saw the upper manhole. I looked west and saw the lower manhole. I visually drew a line between them – that’s where the street main is.

The station was 100 feet from the upper manhole (350 feet minus 250 feet) and 200 feet from the lower manhole (550 feet minus 350 feet). I walked to the closer of the two manholes, in this case the upper, east of the property.

With a 100-foot measuring tape, I measured from the center of that manhole along my visual string line for a distance of 100 feet. I was now standing directly above the house’s street connection (8-inch by 6-inch wye) in the middle of the street.

From that point I measured straight back toward the property for a distance of 25 feet, my lateral length. I was now on the edge of the sidewalk closest to the house – the property line. Directly below me, 5 feet deep, was the connection the contractor had been looking for. It took just a couple of minutes.

What you need

This method will be enough to tell you where the connection is, and whether the line runs under a driveway or retaining wall or goes to an easement. That’s what we needed to know. The contractor now knew where his excavation would start, where it would end, and how deep his final connection would be.

If he were to expose the old pipe and lay the new one in exactly the same trench, any other tie-ins would be exposed automatically and tied into the new sewer. Just reconnect them to the new pipe. Usually, you can see any additional connections with your camera, but in this case we were blind.

In this case, there were many mature trees above the old sewer with large surface roots that needed to be chopped or cut to get to the old line. It was obvious that a reroute of the sewer was in order. It would save time, work and money. Cutting all those roots may kill the trees as well, and it just wasn’t necessary.

Once again, the contractor became a little nervous of extra connections that needed to be rerouted, and he was ready to spike his bid higher (just in case) in the event of extra work. I assured him that we could find out with a very simple test, at least in this case, if there were any connections that we would miss on a reroute.

We cut the original line 2 ft from the house (see drawing), where the building drain becomes the sewer, where our excavation would begin and the required building cleanout would be installed. Now, one at a time, we ran water in each fixture to see if it flowed to where we had just cut the line. They all did – great.

We checked around for other fixtures that may have been added during a remodel. Laundry drains in a garage are always suspect. If all drains flow to where you’ve cut the sewer, there will be no other tie-ins along the sewer path. You may reroute with confidence, trenching a path of least resistance.

If any fixture had drained outside of our test area, it would have to be located separately and routed to our new line. This may all sound overwhelming, but I assure you it is not difficult. This may be an ideal time to sell a new water service, too. Usually you can use a portion of the same trench for both sewer and water. This combination saves your customer money and gives you a bigger sale – it is a win-win deal.

Public or private?

A word of caution is appropriate here. In several cities around the Los Angeles area, and I can only assume the same is true for the rest of the country, the lateral pipe is considered a private pipe. Before you start selling sewers, call your local engineering department, located within the department of building and safety and ask this important question: Who is financially responsible for sewer lateral repairs?

Do not proceed until you have the answer. This is a critical piece of information, and here’s why: If you tell a customer that replacing their sewer from the house to the property line will absolutely solve the problem – look out!

Suppose you replaced the sewer and then found the lateral to be an additional needed repair. Your promise to solve the problem at a fixed-bid price may cost you thousands of dollars. Customers always assume that their financial responsibility ends at the property line – but that may not be true.

You may end up in court, and chances are, you’ll lose. The court’s position is that you are the professional, not the homeowner, and you should know better. If you cannot inspect the lateral with your camera, let your customer know that. Also, tell them that if a lateral repair is needed, they have to pay for it, even though it is on public property.

Reinforce this statement on your contract with the homeowner. Are you licensed to dig up the street? A plumber’s contractor license is not sufficient. You may need to bring in a specialty contractor.

A lateral repair usually costs between $1,800 and $4,000 for just the section under the parkway grass. Lateral repairs under the street start at $5,000 and can be very costly under a high-traffic street. You haven’t lived until you’ve replaced a tough lateral under a busy street, 14 feet deep in sandy soil that continually caves in, and you couldn’t use a backhoe because there was a myriad of main gas lines, water lines and telephone fiber-optic cables you need to weave through to get to your pipe. It happens!

I have been involved in several such residential lateral repairs that have cost homeowners in excess of $10,000. Arm yourself – no surprises for you or your customer. If you can’t inspect a lateral with your camera before you break ground, never assume that it’s OK. Cover yourself. n

Peter Morici is a business coach and sales trainer based in Shelby Township, Mich., providing resources specifically for the service contracting community. Readers may direct inquiries to his Web site at


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