Septic + Leaching Field Designer — Ebora Engineering Utilities 1

🚽 Septic Tank · Leaching Field

Septic + Leaching Field Designer

Size a household or building septic tank and its soil-absorption (leaching) field. Enter the number of users, sewage flow, detention time and a sludge allowance — the app finds the liquid & sludge volumes, the required tank L × W × depth, then sizes the absorption field from the soil percolation rate.

⭐ Free to use · Balance … EP

① Occupancy & sewage flow

Number of users (persons)

Sewage flow per person (L/person·day)

Typical 120–200 L/p·d for full plumbing. Verify with your code.

Detention / retention time (days)

Commonly 1 day (24 h). Some codes use less for high flow.

Air space / freeboard (m)

Above the liquid level, default 0.30 m.

② Sludge storage & tank shape

Sludge & scum accumulation (m³/person·year)

Typical 0.03–0.05 m³/p·yr of stored, partly-digested sludge.

Desludging interval (years)

Years between clean-outs (commonly 3–5).

Liquid depth (m)

Effective liquid depth, default 1.2 m (min ≈ 1.0 m).

Length : Width ratio

Plan ratio L/W, default 3 (keep 2–4).

③ Leaching / absorption field

Percolation rate P (minutes per 25 mm drop)

Uses the standard LTAR = 5/√P (gal/day·ft²) percolation relation, converted to SI. P is the soil perc-test rate (min per 25 mm ≈ min/inch).

Soil loading rate (L/m²·day)

Long-term acceptance rate from your soil table / code.

Trench width (m)

Max length per trench (m)

🚽 Septic system design

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Septic tank + soil absorption field

Septic tank

Daily sewage flow

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Liquid (detention) vol.

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Sludge & scum vol.

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Required capacity

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Tank length L

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Tank width W

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Liquid depth

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Total depth (+freeboard)

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Plan area

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Leaching / absorption field

Effluent flow

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Soil loading rate

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Required area

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Total trench length

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No. of trenches

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Length / trench

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Worked solution

⚠️ Verify before construction. Sewage-flow, sludge, detention and soil-loading values are typical design figures. Tank minimums, perc-test procedure, and absorption-field rules must follow the National Plumbing Code of the Philippines, the DENR/LWUA sanitation guidelines, and your local (LGU) sanitary code. This tool is a study/estimating aid.