Converting From Septic to City Sewer: Cost and Process

When Conversion Makes Sense

Converting to city sewer is not always available or practical, but when it is an option, it makes financial sense in several situations. The most common trigger is a failing septic system on a property where municipal sewer has recently been extended to the street. If your septic system needs $10,000 to $25,000 in replacement and the sewer connection costs $5,000 to $10,000, connecting to the sewer eliminates the septic system entirely and removes all future replacement and maintenance costs.

Mandatory connection ordinances exist in many municipalities. When a city extends sewer service to a previously unserved area, property owners may be required to connect within a specified timeframe, often one to three years. Some ordinances require connection only when the existing septic system fails, while others require connection regardless of the septic system's condition. Check with your municipal public works department to understand whether a mandatory connection ordinance applies to your property.

Properties with chronic septic problems due to poor soil conditions, small lot sizes, or high water tables are natural candidates for conversion. A property that has already replaced its drain field once and faces the prospect of another $15,000 replacement may find that the sewer connection cost is a better long-term investment.

Selling a home on sewer is generally easier than selling one on septic. Buyers do not need to worry about septic inspections, maintenance schedules, or potential replacement costs. While this alone may not justify the conversion cost, it is worth considering if you plan to sell in the near future.

Cost Breakdown

Connection Fee

The municipality charges a connection fee, sometimes called a tap fee or impact fee, for the right to connect to the sewer system. This fee ranges from $1,000 to $10,000 or more depending on the municipality. The fee covers the cost of expanding sewer capacity to serve the new connection and is typically a one-time charge payable at the time of connection. Some municipalities offer payment plans that allow the connection fee to be spread over several years and added to the property tax bill, which reduces the upfront financial burden.

Lateral Installation

The sewer lateral is the pipe that runs from your home to the sewer main in the street. The property owner is responsible for installing and maintaining this pipe. Installation costs $1,500 to $5,000 for a typical residential property, depending on the distance to the main, the depth of the main, and any obstacles (driveways, sidewalks, landscaping) that the pipe must cross. Longer laterals and deeper mains increase the excavation cost.

The lateral material is typically four-inch or six-inch PVC pipe. The pipe must slope toward the main at a minimum grade of one-quarter inch per foot to maintain gravity flow. If the property's elevation does not allow gravity flow to the main, a grinder pump station is required, adding $2,000 to $5,000 to the project. The grinder pump breaks down solids and pushes wastewater uphill through a pressurized force main to reach the municipal connection point.

Interior Plumbing Modifications

Most homes with septic systems have plumbing that exits the house at the same location and elevation whether connected to a septic tank or a sewer lateral. In these cases, the connection point simply shifts from the septic tank to the new lateral pipe and no interior modifications are needed.

However, some homes require plumbing modifications to accommodate the new connection. If the sewer main is higher than the home's drain exit, a lift station or ejector pump may be needed, adding $1,000 to $3,000. If the home has a basement with below-grade plumbing, a backwater valve should be installed to prevent sewer backup, adding $200 to $1,000.

Septic System Decommissioning

The old septic system must be properly decommissioned according to local regulations. This typically involves pumping the tank, disconnecting all inlet and outlet pipes, crushing the tank in place or removing it entirely, and filling the void with clean sand or gravel. Decommissioning costs $1,000 to $3,000. The drain field is usually left in place because it is inert once disconnected from the tank and does not need to be removed. Some jurisdictions require the decommissioning to be inspected and documented by the health department before a completion certificate is issued.

If the tank is removed rather than crushed and filled, the excavation and hauling cost is higher but the approach eliminates any concern about future settling over the filled void. Concrete tanks are heavy (a 1,000-gallon concrete tank weighs approximately 4,500 pounds) and require heavy equipment to lift out, which is one reason most contractors recommend crushing in place when regulations allow it.

Total Conversion Cost

Adding these components together, a typical residential conversion runs $3,000 to $15,000. Properties close to the sewer main with modest connection fees land at the lower end. Properties farther from the main, in municipalities with high connection fees, or requiring interior plumbing modifications land at the higher end.

The Conversion Process

The process begins with contacting your municipal public works or utilities department to verify that sewer service is available at your property, understand the connection requirements and fees, and submit an application to connect. Some municipalities have waiting lists or seasonal connection windows.

Once approved, hire a licensed plumber or sewer contractor to install the lateral from your home to the main. The municipality may perform the actual connection to the main (the tap), or they may authorize your contractor to do it under their supervision. An inspection is typically required before the connection is activated and the trench is backfilled.

After the sewer connection is active and verified, the septic system is decommissioned. The tank is pumped, disconnected, and either removed or crushed and filled. A final inspection may be required to verify that the decommissioning was done properly.

The entire process, from initial application to completed decommissioning, typically spans four to twelve weeks. The permit and approval phase accounts for most of that time, while the physical work of installing the lateral and decommissioning the septic usually completes within one to two weeks.

Ongoing Cost After Conversion

After converting, you will pay a monthly sewer bill that you did not have with the septic system. Sewer charges are typically based on water usage and range from $30 to $100 per month for a typical household, or $360 to $1,200 per year. This replaces the $100 to $200 per year average cost of septic pumping amortized over the pumping interval.

The trade-off is certainty. The monthly sewer bill is predictable and eliminates the risk of a $5,000 to $25,000 surprise repair or replacement. For homeowners who value predictable expenses over lower average costs, the trade-off often makes sense.

Special Assessment Districts

When a municipality extends sewer lines to a new area, the cost of the sewer main construction is often spread among the property owners who benefit from it through a special assessment district. The assessment can range from $5,000 to $20,000 per property, typically payable over 10 to 20 years through the property tax bill. This cost is separate from and in addition to the connection fee and lateral installation cost described above.

If your property is in a newly assessed area, the total cost of conversion includes the assessment plus the connection and installation costs, which can make the total financial commitment substantially larger than the connection costs alone. However, the assessment is sometimes mandatory regardless of whether you choose to connect, particularly in areas where the municipality is replacing aging septic systems with centralized sewer service for environmental protection reasons.