Dholera Rainwater Harvesting Guidelines: DSIRDA Recharge Well Rules

1. DSIRDA Mandatory Plot Thresholds

The regulations outline specific requirements for residential, commercial, and industrial plots:

• Mandatory Cut-off: Every building with a plot footprint of 100 square meters or more must construct an active rainwater harvesting (RWH) setup.
• Storage Sump Sizing: If a developer opts for a storage tank, the capacity must be calculated at a minimum of 20 liters per square meter of roof catchment area.
• Recharge Wells: For larger plots, excess rooftop runoff must be directed to an aquifer recharge well rather than flowing into the public storm drains.

2. Technical Filtration and Construction Standards

To ensure harvested water does not contaminate the local aquifer, the GDCR specifies standard filtration layer dimensions:

• Silt Traps: Downtake pipes from roof drains must first route water into a silt trap chamber to collect leaves, sand, and dust.
• Filtration Chamber Layers: The water must pass through a concrete filter chamber containing the following layers from top to bottom:
• Recharge Well Specifications: Recharge wells must be a minimum of 3.0 meters deep, lined with perforated concrete rings, and backfilled with gravel to allow water to seep into the soil.

The table below outlines RWH design specifications under DSIRDA:

3. Environmental Impact: Combatting Aquifer Salinity

Dholera’s proximity to the Gulf of Khambhat makes its groundwater naturally saline. Implementing rainwater harvesting across the city serves a key environmental purpose:

• Freshwater Barrier: Injecting clean rainwater into the ground creates a freshwater lens that pushes back subsurface saltwater intrusion.
• Reducing Runoff: Keeping water on-plot reduces flow inside public stormwater channels during heavy monsoon events.
• Industrial Reuse: Many factories in TP2 treat and use harvested rainwater for cooling towers, reducing reliance on potable water supplies.

Frequently Asked Questions (FAQ)

#### Is rainwater harvesting mandatory for small plots in Dholera?

Yes. Under DSIRDA GDCR Section 11.2, any building constructed on a plot of 100 square meters or larger must have a functional rainwater harvesting system.

#### What happens if I don’t build a rainwater harvesting system?

DSIRDA will not issue a building Occupancy Certificate (OC) unless the rainwater harvesting installation has been inspected and certified by a registered engineer.

#### How deep must a recharge well be in Dholera?

Recharge wells must reach a minimum depth of 3.0 meters from the surface, utilizing perforated concrete rings to allow water filtration into the soil.