Determine minimum septic or holding tank size for a Nebraska onsite wastewater system under Title 124

Steps

1. Identify whether the system serves a dwelling or a non-dwelling facility, since minimum tank capacity rules differ.
2. For a dwelling septic tank, use Table 10.1 of Title 124: look up minimum capacity by design flow (gallons per day) and whether a garbage grinder or large-capacity tub (over 50 gallons working volume) is present; minimums range from 1,000 gallons at 200 gpd design flow up to 3,000 gallons at 1,000 gpd with both a grinder and large tub.
3. For a non-dwelling septic tank, size at 1,125 gallons plus 0.75 times design flow (gpd) for flows over 1,500 gpd, or 1.5 times design flow for flows of 1,500 gpd or less, with a 1,000-gallon floor.
4. For a dwelling holding tank, size at a minimum of 1,000 gallons for two or fewer bedrooms, plus 300 gallons for each additional bedroom.
5. Double the required tank capacity if the system will receive high-strength or high-temperature wastewater (e.g., laundry, restaurant, butcher shop, or camper dump station).
6. Confirm current requirements directly on dwee.nebraska.gov, the Nebraska Department of Water, Energy and Environment (DWEE) site; the former NDEE/dee.nebraska.gov domain is stale following the 2025 agency merger.