Conventional gravity, mound (for high-water-table sites), drip irrigation, and chambered. Cincinnati area uses mostly conventional + chambered for new builds. Mound systems are required where perc rates fail standard testing.
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Five main drain-field types in Greater Cincinnati. (1) Conventional gravity: 200-800 linear feet of perforated pipe in gravel-filled trenches, gravity-fed from the distribution box. Cheapest option, requires good perc and adequate setback. (2) Chambered systems: similar to conventional but uses molded plastic chambers (Infiltrator) instead of gravel, allowing smaller footprint. Common in new Cincinnati construction. (3) Mound systems: when high water table or restrictive soil makes a below-grade field impossible, an above-grade mound of imported sand provides treatment. More expensive ($12,000-$20,000) but works on otherwise-unsuitable lots. (4) Drip irrigation: pressure-distributed effluent through small drip lines across a larger area, often used on tight or sloped lots. Higher upfront cost but excellent for marginal soils. (5) Aerobic treatment unit (ATU) with surface discharge: under Ohio EPA permit, ATU effluent can sometimes discharge to a stream rather than a drain field. Common near streams or in failed-perc lots. Cincinnati installation cost ranges by type: conventional gravity $6,000-$12,000 installed; chambered $7,000-$13,000; mound $12,000-$20,000; drip $15,000-$25,000; ATU with surface discharge $14,000-$22,000 plus permitting costs. Local contractors recommend the cheapest type that the lot will support with adequate longevity; cheaper systems on marginal lots are false economy.