Rex says
Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.
Try a scenario
Click to load — tweak from there.Inputs
Result
Lower total cost option
Septic
Septic total cost
$11,400
Sewer total cost
$17,700
Difference over horizon
$6,300
Breakeven year
8.5
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How to use this
- 1Enter septic system install cost ($).
- 2Enter cost per pumping ($).
- 3Enter pumping interval (years).
- 4Enter sewer tap/connection fee ($).
- 5Enter sewer monthly fee ($).
- 6Enter years to project.
- 7Read your lower total cost option on the right — it updates as you type.
- 8Hit Share to keep the scenario or send it to someone.
About this calculator
A septic system costs more to install than connecting to sewer in most cases but has no ongoing bill beyond periodic pumping, while a sewer connection often has a large one-time tap fee followed by a monthly or quarterly charge indefinitely. This tool totals both paths over your ownership horizon so you can see which is cheaper for how long you plan to stay.
Worked example
Using the values the calculator loads with:
Inputs
- Septic system install cost: 9000 $
- Cost per pumping: 400 $
- Pumping interval: 3 years
- Sewer tap/connection fee: 4500 $
- Sewer monthly fee: 55 $
- Years to project: 20
Results
- Lower total cost option: Septic
- Septic total cost: $11,400
- Sewer total cost: $17,700
- Difference over horizon: $6,300
- Breakeven year: 8.5
What each field means
Inputs
- Septic system install cost ($)
- The septic system install cost used in the calculation, measured in $. Starts at 9000 $ so you have a working example on load.
- Cost per pumping ($)
- The cost per pumping used in the calculation, measured in $. Starts at 400 $ so you have a working example on load.
- Pumping interval (years)
- The pumping interval used in the calculation, measured in years. Starts at 3 years so you have a working example on load. Accepted range: 1–10 years.
- Sewer tap/connection fee ($)
- The sewer tap/connection fee used in the calculation, measured in $. Starts at 4500 $ so you have a working example on load.
- Sewer monthly fee ($)
- The sewer monthly fee used in the calculation, measured in $. Starts at 55 $ so you have a working example on load.
- Years to project
- The years to project used in the calculation. Starts at 20 so you have a working example on load. Accepted range: 1–40.
Results
- Lower total cost option
- Returned as a plain value and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Septic total cost
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Sewer total cost
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Difference over horizon
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Breakeven year
- Returned as a length of time. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
Do I get a choice between septic and sewer?
Often not — many municipalities require connection to sewer if a line runs within a set distance of your property, regardless of which is cheaper.
How long does a septic system last?
A well-maintained septic system with regular pumping can last 25-40 years before the drain field needs replacement, a major cost not included here.
Is sewer connection ever mandatory even with a working septic?
Yes, some jurisdictions require connection within a set period once sewer becomes available nearby, even if your septic system is functioning fine.
Accuracy and limitations
- Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
- Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
- This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Septic vs Sewer Cost Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/septic-vs-sewer-cost
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/septic-vs-sewer-cost" target="_blank" rel="noopener">Septic vs Sewer Cost Calculator — RevenueLab</a> (2026).</p>
Source: [Septic vs Sewer Cost Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/septic-vs-sewer-cost) (2026).