Question 1

How much does a septic system cost to install in 2026?

Accepted Answer

Most residential septic installations run about $4,000 to $8,000 for a conventional gravity system, and $10,000 to $20,000 for an aerobic treatment unit or an engineered mound system, depending on soil, region, and household size. Total project costs of $3,000 to $25,000 are all within normal range across system types.

Question 2

What size septic tank do I need for a 3-bedroom house?

Accepted Answer

Most codes size a septic tank at 750 gallons for 1-2 bedrooms, 1,000 gallons for 3 bedrooms, 1,250 gallons for 4 bedrooms, and 1,500 gallons or more for 5+ bedrooms, based on 150 gallons of daily wastewater flow per bedroom.

Question 3

How much does a perc test cost?

Accepted Answer

A percolation (perc) test typically costs $300 to $1,900, with most homeowners paying around $750 to $1,300 depending on how many holes are dug, whether an excavator is needed, and local permitting requirements.

Question 4

What's the difference between a conventional and an aerobic septic system?

Accepted Answer

A conventional system relies on gravity and untreated soil bacteria and has no moving parts. An aerobic treatment unit (ATU) actively pumps oxygen into the tank to break down waste faster, producing cleaner effluent that needs a smaller dispersal field — useful on tight or poor-soil lots — but it costs roughly double and requires an annual service contract.

Question 5

How much does a mound septic system cost?

Accepted Answer

A mound septic system typically costs $10,000 to $20,000 or more installed, since it requires engineering, a pump, and importing sand and gravel to build a raised absorption bed above natural grade — it's the standard fix when a lot fails a conventional perc test.

Septic tank (material + setting)	$500 – $1,000
Drain field / leach field	$1,800 – $3,600
Excavation & site prep	$1,100 – $2,200
Permits, perc test & inspection	$600 – $1,200

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