Catchment and yield assessment
Roof and paved catchment areas, local rainfall data and runoff coefficients to establish harvestable volume.
Sustainability
Rain Water Harvesting
Catchment-based rainwater systems for campuses, townships and infrastructure sites — sized from real rainfall and roof area, and integrated with landscape irrigation.
Rainwater harvesting on Indian sites is frequently installed and rarely maintained. Recharge pits silt up within two monsoons, first-flush arrangements are omitted, filter media is never changed, and the system quietly stops working while remaining on the compliance drawing.
Designing it properly is arithmetic before it is engineering: catchment area times rainfall times a runoff coefficient gives the harvestable volume, and that number decides whether the site should store, recharge, or both. Storage makes sense where there is a use — landscape irrigation is usually the largest one — and recharge makes sense where groundwater is the resource under stress.
We design and support implementation with the landscape in mind, because on most campuses irrigation is both the biggest water consumer and the easiest one to supply from harvested rain.
Specification notes
| Yield formula | Catchment area × rainfall × runoff coefficient (0.8–0.9 for roofs) |
|---|---|
| First flush | Typically the first 1–2 mm of rainfall diverted before collection |
| Recharge sizing | Governed by soil infiltration rate, not by catchment alone |
| Critical maintenance | Pre-monsoon desilting and filter media replacement every year |
| Best reuse | Landscape irrigation — usually the largest non-potable demand on site |
What you get
- A system sized from real numbers rather than a standard detail
- Landscape irrigation partly supplied by harvested rain
- Recharge structures that still function in their fifth monsoon
- Compliance satisfied by a working system rather than a drawing
Scope
What the service covers
Recharge structure design
Recharge pits, trenches and bore recharge sized to soil infiltration, with silt traps and desilting access.
Storage and reuse
Tank sizing against irrigation demand, with pumping and distribution into the landscape system.
Filtration and first flush
First-flush diversion, filter media selection and the maintenance access that keeps them functioning.
Landscape integration
Swales, bio-retention and permeable surfaces that slow runoff and recharge in the landscape itself.
Maintenance protocol
Pre-monsoon desilting, filter servicing and a written schedule with responsibility assigned.
Method
How the work runs
- 1. Site hydrologyCatchment mapping, existing drainage behaviour, soil infiltration and groundwater context.
- 2. Yield calculationHarvestable volume against local rainfall, and demand-side assessment for reuse.
- 3. System designStorage-versus-recharge split, structure sizing, filtration and overflow routes.
- 4. Implementation supportDrawings, specifications and supervision during construction.
- 5. Maintenance handoverPre-monsoon checklist and a maintenance schedule with named ownership.
Plant library
Species we commonly specify for this work
Each entry carries mature size, spacing, water demand, planting window and the maintenance cycle it commits you to.
Vetiver
Chrysopogon zizanioides
The engineering plant of Indian landscapes: a deep-rooted clumping grass that holds embankments, filters runoff and stops erosion where nothing else will grow.
- Height1–1.5 m clump; trimmed to 300–500 mm in ornamental use
- WaterLow once established
- MaintenanceLow
Arjuna
Terminalia arjuna
A large, buttressed native with smooth pale bark and a spreading canopy — the best avenue tree for moist alignments, riverbanks and canal-side roads.
- Height20–25 m
- WaterModerate to high
- MaintenanceLow
Wedelia
Sphagneticola trilobata
The fastest green cover in Indian landscaping — a yellow-flowered creeper that blankets slopes and bed edges in months, and needs a hard edge because it will not stop.
- Height150–300 mm
- WaterModerate
- MaintenanceModerate — mostly containment
Jamun
Syzygium cumini
A dense evergreen native that holds its canopy through the hot season and supports serious urban bird life — Delhi’s classic avenue tree, with one fruit-stain caveat.
- Height15–20 m
- WaterModerate
- MaintenanceLow
Frequently asked questions
How much rainwater can a campus harvest?
Multiply catchment area by annual rainfall by a runoff coefficient of about 0.8 for roofs. A 5,000 sq m roof in a 700 mm rainfall zone yields roughly 2.8 million litres a year before losses — usually a significant fraction of landscape irrigation demand.
Should we store rainwater or recharge it?
Store where there is a genuine year-round use, typically landscape irrigation or flushing. Recharge where groundwater is the stressed resource and storage would sit unused. Most sites benefit from a combination.
Why do recharge pits stop working?
Silt. Without a silt trap and annual pre-monsoon desilting, a recharge pit chokes within two or three seasons and the system becomes decorative. The maintenance schedule matters as much as the design.
Read next
Guides on this subject
Water · 5 min read
Drip Irrigation Design for Indian Landscapes
How to size, zone and maintain landscape irrigation: hydro-zoning, emitter selection, run-time calculation, filtration, and the maintenance regime that keeps a drip system working past year two.
Read the guideSustainability · 4 min read
Green Audit Framework for Indian Campuses
What a green audit measures, how to run one, and the findings that recur on Indian sites — water balance, irrigation waste, waste streams, green cover and the roadmap that turns data into decisions.
Read the guideRelated
Services usually taken alongside this one
Sustainability
Green Auditing
A structured baseline of how a site actually performs on water, waste, energy, landscape and biodiversity — with a prioritised roadmap instead of a certificate.
Service detailCore service
Landscape Execution and Plantation
Full softscape execution for campuses, townships, industrial sites and public realm — from soil and levels through planting, lawns and irrigation to a working maintenance handover.
Service detailSustainability
Waste Management Solutions
Practical waste systems for campuses, industrial sites and townships — segregation that people actually follow, on-site organic processing, and documentation that satisfies compliance.
Service detailPlanning a plantation, landscape or green wall package?
Send the site details, the drawings if you have them, and the maintenance budget you expect. You will get an honest read on species, timing and what the site can actually sustain.