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Septic installation · 2026 · all 50 states + DC

How much does a septic system cost in your state?

Answer four questions about your home and lot — bedrooms, system type, soil, and state — and get an itemized installed-cost estimate. All 50 states and DC, adjusted with published May 2025 government wage data. Free, no signup, no phone number.

Estimate your septic system cost

Four questions, updates instantly.

1 · How many bedrooms does the house have?
2 · What system type?

Not sure? Most homes with decent soil use conventional — see the buying guide to check which applies to you.

3 · What's your soil / perc-test result like?
4 · What state are you in?

State adjusts the labor share of the job using BLS May 2025 construction wages for your state — see the method. All 50 states and DC are covered.

Estimated installed cost — Conventional Gravity, 3 bedrooms (1,000-gal tank), Average soil, Washington
$4,600 – $9,100

Where the money goes

Septic tank (material + setting)$600 – $1,100
Drain field / leach field$2,100 – $4,100
Excavation & site prep$1,300 – $2,500
Permits, perc test & inspection$700 – $1,400

This is a budgeting estimate synthesized from published 2026 installer pricing, scaled for your bedroom count, soil, and state labor market — not a substitute for a written local bid. Get matched with a local installer →

Where the money goes, underground

The tank is the cheap part

It's natural to think of a septic system as a tank. In the calculator's own breakdown the tank is 12% of a conventional install and the drain field is 45%, and the field is also where an unpumped tank's problems end up.

Cross-section of a conventional septic system Wastewater runs from the house through the sewer line into a buried septic tank, where it separates into scum, effluent and sludge. Effluent flows to a distribution box and out into drain-field trenches of gravel and perforated pipe, then filters down through unsaturated soil above the water table. For a 3-bedroom conventional system the calculator puts the tank at 12% of installed cost, the drain field at 45%, excavation at 28% and permits and the perc test at 15%. TOPSOIL UNSATURATED SOIL WATER TABLE / GROUNDWATER 1 7 DIGGING 28% SCUM EFFLUENT SLUDGE 3 4 DISTRIBUTION BOX 5 DRAIN FIELD 45% · $1,800 – $3,600 BIOMAT 6 THE SOIL DOES THE CLEANING 8 PERMITS + PERC TEST 15% 2 TANK 12% · $500 – $1,000
Schematic, not to scale. Percentages and dollar ranges are this site's calculator breakdown for a 3-bedroom conventional system, average soil, national average; other systems and states split differently (the drain field or mound is 55–58% on aerobic and mound systems). Numbered parts link to the guide for each.

To scale: drain field · digging & site prep · permits & perc test · tank. Total $4,000 – $8,000 for a 3-bedroom conventional system at the national average.

  1. 1Sewer linenot itemized
    Carries everything from the house to the tank. Following it out is how you find the tank; EPA says the access riser is usually about 10 feet from the house.
    How to find your septic tank →
  2. 2Septic tank12% · $500 – $1,000
    The cheap part. A concrete tank can last 50 years or more, per EPA. Its job is to hold back solids, so the usual failure is not the tank breaking but the tank going unpumped.
    Pumping cost → · Replacement →
  3. 3Scum, effluent, sludgethe layers
    Solids sink, grease floats, the liquid between flows on. When sludge and scum build up near the outlet, solids get pushed out into the drain field and clog it.
    Signs the tank is full →
  4. 4Distribution boxnot itemized
    Splits the effluent between the trenches. An inspection opens it along with the tanks.
    Inspection cost →
  5. 5Drain field45% · $1,800 – $3,600
    The expensive part, and where trouble ends up. The biomat at the bottom of the trenches thickens with age (EPA: fields over 25 to 30 years old), and solids from an unpumped tank, too much water, roots and vehicles can all ruin a field.
    Drain field replacement → · How long parts last →
  6. 6Unsaturated soildoes the treating
    The soil under the trenches removes bacteria, viruses and nutrients before the water reaches groundwater. That is why the system needs enough dry soil above the water table.
    How a septic system works →
  7. 7Digging & site prep28% · $1,100 – $2,200
    The dashed outlines: the hole for the tank and every trench.
    Conventional system breakdown →
  8. 8Permits & perc test15% · $600 – $1,200
    The perc test measures how fast the soil drains, and it decides which system you can build. Poor results often mean a mound or aerobic system instead.
    Perc test cost → · Permits by state →

Septic system costs at a glance

Typical installed range by system type at the national average, before adjusting for your soil and state.

Conventional Gravity
$4,000 – $8,000

Most home sites with soil that drains reasonably well and enough land for a standard field.

See full breakdown →
Aerobic Treatment Unit (ATU)
$10,000 – $20,000

Small or tight lots, marginal soil, or counties that mandate a higher treatment standard before dispersal.

See full breakdown →
Mound / Sand-Filter System
$10,000 – $20,000

Shallow soil over rock or clay, a high water table, or a lot too thin/steep for a standard field.

See full breakdown →

Ready to get real numbers?

A calculator can't see your lot. We're building a network of local septic installers who can quote your actual project — tell us where you are and what you need.

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Septic questions, answered

Pumping, repairs, inspections, drain fields and more, with every cost figure sourced and dated.

How much does it cost to pump a septic tank?Septic tank pumping typically costs $292 to $565, about $428 on average (HomeAdvisor, June 2026).How much does it cost to replace a septic tank?Replacing just the septic tank typically costs $3,000 to $10,000 (HomeAdvisor, June 2026).How does a septic system work?A septic system is a buried tank plus a drain field: solids settle in the tank, and the liquid soaks into soil that treats it.How long does a septic system last?How long septic tanks, pumps and drain fields last, per EPA and HomeAdvisor, where the two disagree, what shortens each part's life, and when to plan a replacement.How do I find my septic tank?Start with the septic permit at your local health department, then trace the sewer pipe out of the house and look for a riser.How much do septic repairs cost?Septic tank repairs typically cost $627 to $3,043, about $1,828 on average, and major repairs run $6,500+ (HomeAdvisor, June 2026).

All septic questions →

Septic system cost by state

The same calculator, adjusted to each state's construction labor market. Cheapest to most expensive: Arkansas at 85% of the national baseline, Hawaii at 125%.

Alabama 86%Alaska 111%Arizona 96%Arkansas 85%California 118%Colorado 98%Connecticut 111%Delaware 96%District of Columbia 104%Florida 90%Georgia 88%Hawaii 125%Idaho 97%Illinois 118%Indiana 105%Iowa 99%Kansas 93%Kentucky 94%Louisiana 90%Maine 94%Maryland 96%Massachusetts 118%Michigan 101%Minnesota 112%Mississippi 87%Missouri 105%Montana 99%Nebraska 95%Nevada 105%New Hampshire 100%New Jersey 121%New Mexico 90%New York 115%North Carolina 91%North Dakota 102%Ohio 106%Oklahoma 89%Oregon 107%Pennsylvania 101%Rhode Island 108%South Carolina 90%South Dakota 93%Tennessee 92%Texas 90%Utah 96%Vermont 97%Virginia 92%Washington 114%West Virginia 92%Wisconsin 108%Wyoming 97%
Independent calculator. We don't install septic systems — we help you budget and (soon) connect you to vetted local installers. Baseline cost ranges are synthesized from published 2026 installer pricing; the state adjustment comes from U.S. Bureau of Labor Statistics May 2025 construction wages. These are planning estimates, not quotes. See how we build these numbers.