Septic & well
Septic System Cost Calculator
Prices a whole system, where the soil decides the cost far more than the house does.
Result
A planning estimate, not a quote. Access, the age of the equipment, what is found once it is opened up and local labour rates all move the real figure, sometimes a long way.
Get a Free Business AuditHow the calculation works
A full system is a tank plus a drainfield, and the arithmetic here totals the labour, materials and equipment for both. The number is dominated by which kind of system the site will accept, and that is determined by a soil evaluation rather than by choice. Soil that percolates well and has enough depth above groundwater or bedrock takes a conventional gravity trench field, which is the cheapest outcome. Poor percolation, shallow soil or a high water table forces an engineered alternative such as a mound, a sand filter or an aerobic treatment unit, each of which costs a multiple of conventional and brings ongoing maintenance with it.
What moves the number
- The soil evaluation and percolation result, which decide the system type and therefore most of the cost.
- Depth to groundwater and to bedrock, since either one close to the surface rules out a conventional field.
- Lot size and setbacks from wells, property lines, surface water and buildings, which can leave very little usable area.
- Whether the site needs a pump to reach the field, adding a pump chamber, controls and power.
Where this one goes wrong
Never quote a system before the soil evaluation. The difference between a conventional field and an engineered alternative is large enough to make any pre test estimate meaningless, and the result is not predictable from looking at a lot. It is also worth establishing early whether there is enough area that meets setbacks at all, because a lot that cannot accommodate a compliant system is a different conversation entirely and better had before money is spent. Engineered systems carry operating obligations too: aerobic units need power, servicing and often a maintenance contract required by the permit, and that is a cost the owner keeps paying.
Before you quote
- Get the soil evaluation and percolation result before quoting anything.
- Confirm there is enough area meeting all setbacks for the required field size.
- Tell the owner about ongoing service obligations if the design is an engineered system.
Where the rules come from
Questions
About this calculator
What makes one septic system cost several times another?
The soil. A site with good percolation and adequate depth takes a conventional gravity field, which is the cheapest design. Poor soil, shallow bedrock or a high water table forces a mound, sand filter or aerobic unit, and those cost a multiple and need ongoing servicing. The house has very little to do with it.
Can I get a price before the soil test?
Not a meaningful one, and any figure given before the test is likely to be wrong by a wide margin in one direction or the other. The test determines the system type, and the system type determines most of the cost. It is worth doing first for exactly that reason.
How much land does a septic system need?
Enough for the field size the soil requires plus a reserve area in many jurisdictions, all of it clear of mandated setbacks from wells, waterways, boundaries and structures. On a small or awkward lot those setbacks can be the binding constraint rather than the soil, which is why the area check comes early.
What is an aerobic treatment unit and why is it more expensive?
It treats effluent more actively before it reaches the soil, which lets it work on sites a conventional field cannot. The trade is that it has moving parts, needs electricity, requires regular servicing and is often subject to a permit condition requiring a maintenance contract. It costs more to install and it keeps costing.
The formula
total = hours x people x rate + parts + call-out, then sales tax
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How to use this calculator
- Hours on site (h). Enter your own figure; the page starts at 2.5 h.
- People needed. Enter your own figure; the page starts at 1.
- Labour rate charged ($). Enter your own figure; the page starts at $155.
- Parts and materials ($). Enter your own figure; the page starts at $120.
- Call-out or diagnostic fee ($). Enter your own figure; the page starts at $95.
- Sales tax (%). Leave at zero if you are quoting before tax.
The result updates as you type, so you can try a figure, see what it does to estimated total, and change it back. Nothing you enter is sent anywhere or saved.
A worked example
These are the figures the calculator opens with. Every number in the results column below is produced by the same calculation the page runs, so you can follow it through before putting your own figures in.
What goes in
| Input | Value |
|---|---|
| Hours on site | 2.5 h |
| People needed | 1 |
| Labour rate charged | $155 |
| Parts and materials | $120 |
| Call-out or diagnostic fee | $95 |
| Sales tax | 0% |
What comes out
| Result | Value |
|---|---|
| Estimated total main result | $602.50 |
| Labour | $387.50 |
| Before tax | $602.50 |
| Sales tax | $0 |
About $602.50: $387.50 of labour, $120 of parts and a $95 call-out.
How sensitive the answer is
Holding everything else steady and changing only labour rate charged, this is what happens to estimated total. It is worth knowing which of your inputs the answer actually hinges on, and which barely move it.
| Labour rate charged ($) | Estimated total |
|---|---|
| $78 | $410 |
| $116 | $505 |
| $155 example above | $602.50 |
| $233 | $797.50 |
| $310 | $990 |
Every other input is held at the example value while this one changes, which is not how a real job behaves. Treat it as a guide to which number matters most, not as five separate quotes.
What each figure means
- Hours on site (h)
- Measured in h, between 0 and 400, starting at 2.5 h.
- People needed
- A number, between 0 and 40, starting at 1.
- Labour rate charged ($)
- A money amount, starting at $155.
- Parts and materials ($)
- A money amount, starting at $120.
- Call-out or diagnostic fee ($)
- A money amount, starting at $95.
- Sales tax (%)
- Leave at zero if you are quoting before tax.
What the results tell you
| Result | What it is |
|---|---|
| Estimated total | The headline result. A money figure. |
| Labour | A money figure. |
| Before tax | A money figure. |
| Sales tax | A money figure. |
Estimating is the easy part
The jobs you never hear about cost more than the ones you mis-measure. BDEVY builds the marketing, systems and automation that bring them in.