| # | Code | Description | Unit | Qty | Rate (₹) | Amount (₹) |
|---|---|---|---|---|---|---|
| 1 | 2.8.1 | ExcavationEarth work in excavation by mechanical means (Hydraulic excavator) / manual means in foundation trenches or drains (not exceeding 1.5 m in width or 10 sqm on plan), including dressing of sides and ramming of bottoms, for all lift, including getting out the excavated soil and disposal of surplus excavated soil as directed, within a lead of 50 m. — All kinds of soil. | Cum | 10.43 | 260.30 | 2,714.93 |
| 2 | 4.1.10 | Pcc BedProviding and laying in position cement concrete of specified grade excluding the cost of centering and shuttering - All work up to plinth level : — 1:5:10 (1 cement : 5 coarse sand (zone-III) derived from natural sources : 10 graded stone aggregate 40 mm nominal size derived from natural sources) | Cum | 0.30 | 6,518.60 | 1,955.58 |
| 3 | 6.23 | Honeycomb BrickHoney-comb brick work 10 / 11.4 cm thick with common burnt clay bricks of class designation 7.5 in super structure above plinth level upto floor V level with cement mortar 1:4 (1 cement : 4 coarse sand). | Sqm | 13.04 | 711.50 | 9,277.96 |
| 4 | 4.1.3 | Cover SlabProviding and laying in position cement concrete of specified grade excluding the cost of centering and shuttering - All work up to plinth level : — 1:2:4 (1 cement : 2 coarse sand (zone-III) derived from natural sources : 4 graded stone aggregate 20 mm nominal size derived from natural sources) | Cum | 0.27 | 7,878.50 | 2,127.20 |
| 5 | 7132 | Manhole CoverCircular shape 450 mm dia precast R.C.C. manhole cover with frame - L.D. - 2.5 | Each | 1.00 | 610.00 | 610.00 |
| 6 | 0287 | Brick Aggr FillBrick Aggregate (Single size) : 40 mm nominal size | Cum | 2.53 | 700.00 | 1,771.00 |
| 7 | 19.6.1 | Vent PipeProviding and laying non-pressure NP2 class (light duty) R.C.C. pipes with collars jointed with stiff mixture of cement mortar in the proportion of 1:2 (1 cement : 2 fine sand) including testing of joints etc. complete : — 100 mm dia. R.C.C. pipe | Metre | 7.50 | 507.05 | 3,802.88 |
| Your inputsPit int. ⌀ 1.5 m · Pit total depth 2.5 m · wall thk 230 mm · Brick-aggregate filling inside pit · Vent pipe height above ground 5 m | TOTAL | ₹22,260 | ||||
- Designed per IS 2470 Part 2 (septic effluent) + IS 15797 (rainwater recharge). The two end-uses share the same construction; only the inlet pipe + flow rate differ.
- Wall thickness 230 mm is standard for soak pits taking septic effluent (handles slight earth pressure from saturated soil). 115 mm is acceptable for storm-water recharge pits where the surrounding soil stays drier.
- Honey-comb brickwork DSR 6.23 has gaps in every alternate row to allow percolation — this is the defining feature vs ordinary brickwork.
- Cover slab is a 75 mm PCC 1:2:4 disc with a circular manhole opening (450 mm dia). For pits below vehicle paths, use a 100 mm RCC slab with 8 mm bars @ 150 mm c/c — switch to DSR 5.X if so.
- Brick-aggregate filling DSR 0287 (basic-rate ₹700/Cum) is a material rate only; add labour for filling ~₹200/Cum manually if budgeting tightly. Default formula fills 65% of net internal volume excluding top 300 mm.
- Excludes: inlet/outlet pipe (CI/PVC 100 mm, ~₹250/m), vent pipe (50 mm dia, ~₹120/m), inspection chamber upstream (for septic pit only).
A **soak pit** (also called percolation pit, leach pit or recharge pit) is a sub-surface cylindrical structure that lets liquid drain through honey-comb brick walls and a permeable bed into surrounding soil. Two common use cases drive its BOQ: (1) **soak-away for septic effluent** — the final treatment stage after a septic tank, sized per IS 2470 Part 2; (2) **rainwater harvesting recharge pit** — captures roof runoff into the aquifer, sized per IS 15797. Both share the same construction: honey-comb brick masonry walls in a cylindrical pit, PCC bed at the bottom, RCC cover slab with a circular manhole cover. This BOQ Builder generates the complete cost per CPWD DSR 2023 — usually under ₹30,000 for a standard 1.5 m diameter × 2.5 m deep pit.
Soak pit vs leach pit vs recharge pit — same construction, different purposes
Naming is regional but the engineering is identical. **Soak pit** (general term) — any cylindrical pit for liquid percolation. **Leach pit** (twin-pit toilet term per SBM-G) — used in pour-flush toilets where each pit takes alternating service for ~3 years. **Recharge pit** (rainwater harvesting term per IS 15797) — captures storm-water runoff for ground-water recharge, often paired with desilting chamber upstream. **Magic pit** (regional Tamil Nadu / Kerala) — same as soak pit, smaller (1 m dia × 1.5 m deep). The common construction: cylindrical excavation, 100 mm PCC bed, honey-comb brick walls (perforations every alternate row), brick-aggregate filling (50-65% by volume), RCC cover slab with manhole cover. Sized by daily inflow + soil percolation rate.
Sizing — how big should the pit be?
**For septic effluent (IS 2470 Part 2 Table 2)**: 5-user system → 1.5 m dia × 2.5 m deep; 10-user → 1.8 m × 3 m; 20-user → 2.5 m × 3.5 m; 50-user → twin pits 2.5 m × 4 m each. **For rainwater recharge (IS 15797 Cl. 5.5)**: pit volume = catchment-area × design-rainfall × runoff-coefficient ÷ soil-percolation-rate. For typical north-Indian conditions: 1 m diameter × 2-3 m deep recharge pit absorbs ~50 m² of roof catchment in an 80 mm/hour design rainfall. Always do a percolation test (BSP test or simple 30 cm × 30 cm pit + water-fall observation) before sizing — clay soils may need 2× the calculated volume.
Why honey-comb brick — and what's the alternative
Honey-comb brickwork (DSR 6.23, ₹711.50/m²) has alternate bricks omitted in every other row, leaving roughly 25% open perforations through the wall. This is the IS 2470 / IS 15797 standard — it lets percolating liquid pass through into surrounding soil while still providing structural containment of the brick-aggregate filling inside. **Alternatives**: (a) PRECAST RCC PERFORATED RINGS — used in urban applications where the soil pressure is high; faster install but ~3× the cost; (b) STONE-BLOCK WALLING — random rubble with open joints; cheaper labour in stone-rich regions (HP/UK) but harder to standardise; (c) GEOTEXTILE-WRAPPED GRAVEL DRAIN — modern alternative for recharge pits, less effective for septic effluent. Default to honey-comb brick for any government tender / SBM scheme work — it's the BIS-blessed pattern.