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Borewell Recharge Design: Sizing, Filter Media, and CGWB Compliance

Borewell recharge is the most cost-effective artificial recharge method for hard-rock aquifers of peninsular India, where over 60% of urban and rural water supply depends on borewells. This guide covers the full design chain: inlet chamber, silt trap, filter media, casing depth, and connection to the borewell annulus.

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When to choose borewell recharge over recharge pits

Borewell recharge is preferred when the top 3–10 m is clayey or low-permeability, when large volumes must be recharged rapidly (>10,000 L/hr), or when an existing dry or low-yield borewell is available for reuse.

Recharge pits and trenches work in sandy or gravelly soils with high infiltration capacity. Rain GEO SAT auto-selects the structure using soil texture from SoilGrids and Bhuvan.

Design components and typical dimensions

A standard borewell recharge system has four components: inlet chamber (1 m × 1 m × 1.5 m), silt trap (0.6 m × 0.6 m × 0.6 m), filter chamber (1.2 m diameter × 2 m deep), and PVC connection to the borewell annulus (100–150 mm).

  • Inlet chamber — receives rooftop or catchment runoff via first-flush diverter
  • Silt trap — coarse sand + gravel to remove suspended solids
  • Filter media — bottom 0.5 m boulders (40–65 mm), middle 0.5 m gravel (20–40 mm), top 0.5 m coarse sand
  • Recharge pipe — perforated PVC into the borewell annulus below casing
  • Overflow — safety pipe at inlet chamber to prevent flooding

Indicative cost and payback

Typical cost for a residential borewell recharge structure in India is ₹18,000–₹45,000 depending on soil excavation difficulty and filter material availability. For a 200 m² rooftop in a 900 mm rainfall zone, harvested volume offsets tanker cost within 2–4 years and typically raises the water table around the borewell by 1–3 m within two monsoons.

Frequently asked questions

Can I recharge a functional (yielding) borewell?
Yes, provided filtration is adequate. Rain GEO SAT recommends triple-media filtration (boulders + gravel + coarse sand) and periodic maintenance every 6 months to prevent clogging.
What is the maximum recharge rate?
For hard-rock aquifers, 10,000–20,000 L/hr per borewell is typical. Alluvial aquifers can accept 50,000+ L/hr. The Expert engine estimates this from aquifer transmissivity.
Do I need CGWB permission?
For artificial recharge into a private borewell for own use, no permission is typically required. Commercial or industrial deep recharge may require SEIAA or CGWA clearance depending on the state.

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Rain GEO SAT calculators use IMD, NASA POWER, Open-Meteo, and CGWB data to deliver engineer-grade rainwater harvesting and groundwater recharge designs.

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