Introduction
Bengaluru’s rainwater harvesting formula already includes paved ground alongside roof area in its calculations. TERRALUX™ PolyMatrix Pro, Koochie Global’s resin bound surfacing system, is engineered for exactly that reality, a permeable surface built to let water move through it. This piece traces how the same logic is showing up in policy across Indian cities, and what it means for how ground cover gets specified.
Rainwater Harvesting Rules Were Built Around Roofs
In Bengaluru, Section 72A of the BWSSB Act, inserted in 2009 and tightened again in 2021, set the template most people still picture when they hear “rainwater harvesting mandate.” A building’s roof sheds a predictable volume of water, so the building is required to store or recharge a matching share of it. New sites of 1,200 square feet and above need a system. Existing buildings of 2,400 square feet and above eventually needed one too. Non-compliance brings penalties, and for new construction, it holds up the occupancy certificate itself.
The compliance formula BWSSB actually applies runs wider than the roof, though. It includes paved open area as a separate line in the calculation, alongside roof area. The driveway, the podium walkway, the plaza between towers, all of it factors into what a project has to demonstrate before it clears. Most specification decisions for that ground are still made on appearance and cost, with little reference to the fact that the ground itself is already inside the compliance math.
Where TERRALUX™ PolyMatrix Pro Fits
TERRALUX™ PolyMatrix Pro was engineered for exactly this ground. It is a resin bound surfacing system: natural aggregate mixed thoroughly with a resin binder, laid and trowelled into a single, monolithic surface. Because the aggregate is fully encapsulated rather than loose on top of a base layer, water does not sit on the surface or run off toward the nearest drain. It passes directly through the resin matrix to a permeable drainage layer underneath, reaching the ground the way rainfall would have before the site was paved at all.
For a project working through Bengaluru’s rainwater harvesting formula, that matters at the level of the paved open area line item specifically. A conventional impermeable finish, tile, block paving, poured concrete, sheds water as fast as possible and contributes nothing to recharge. A permeable surface like TERRALUX™ PolyMatrix Pro is formulated to do the opposite. The ground stops being a liability in the calculation and starts contributing to it.
The Same Question, City by City
Bengaluru is not the only city working through this, and its mandate is not even the oldest. Mumbai’s Municipal Corporation made rainwater harvesting compulsory for plots over 1,000 square metres back in 2002, a requirement since folded into the Development Control and Promotion Regulations, DCPR 2034, and reinforced at the state level by the Maharashtra State Water Policy of 2019. Nationally, the Ministry of Housing and Urban Affairs issued Standard Operating Procedures on urban flooding in 2017 and a full Storm Water Drainage Systems Manual in 2019, building on the National Disaster Management Authority’s guidelines from 2010. Programmes such as AMRUT 2.0 and the Smart Cities Mission are increasingly folding flood resilient infrastructure into what gets funded and approved.
There is no single national code tying these together the way the UK’s SuDS framework does. What exists instead is a set of city and state instruments, moving at different speeds and enforced with different rigor, that keep arriving at the same requirement: manage water close to where it falls rather than routing all of it downstream. Wherever that requirement lands, a permeable surface is one of the more direct ways of meeting it, because it addresses the water at the exact point where the specification decision gets made.
The TERRALUX™ Standard
TERRALUX™ PolyMatrix Pro is built on one premise: water should move through a surface, not off it.
What SuDS Actually Means
Sustainable Drainage Systems, or SuDS, is the term used in UK water and engineering practice for this general approach: managing rainfall close to where it lands instead of moving it into a pipe as fast as possible. It rests on four goals, water quantity, water quality, amenity, and biodiversity, delivered through tools such as green roofs, swales, soakaways, rain gardens, and permeable paving.
Permeable paving is the tool that applies most directly to a development’s outdoor ground cover, because it uses space the project was already going to pave rather than requiring new space set aside for it.
TERRALUX™ PolyMatrix Pro sits in this category. Its permeability comes from how the material is formulated and installed throughout, from the resin matrix down through the drainage layer and sub-base beneath it.
Rainfall Intensity Has Outpaced Drainage Capacity
Even where drainage infrastructure exists, most of it was engineered for a gentler climate than the one Indian cities are experiencing now. By some estimates, over seventy percent of urban India’s stormwater drains were designed for rainfall of twelve to twenty millimetres an hour. Cloudburst events are now regularly delivering fifty to a hundred millimetres an hour.
Bengaluru’s own rainfall record shows the pattern building year over year. Pre-monsoon rainfall reached 130 millimetres in twelve hours in 2024, above the 114.6 millimetre high recorded in May 2022. Mumbai flooded again in early July 2026, with arterial roads and the Mumbai-Pune highway shut within a single afternoon.
Rebuilding underground drainage networks at the pace rainfall intensity is increasing takes years most cities do not have. Surface level permeability, the kind TERRALUX™ is designed to provide, works on a different timeline. It installs at the pace of the project itself, and it starts managing water the day it cures.
What This Means at the Specification Table
Bengaluru’s formula, Mumbai’s regulations, and the national manuals do not name TERRALUX™ or any specific product. Together, though, they describe a specification environment where the ground itself carries more regulatory weight than it used to, and where a surface’s water behaviour matters alongside its finish and its wear rating.
TERRALUX™ PolyMatrix Pro does not replace the storage tanks, recharge wells, or dual piping systems a project may still need elsewhere on site. It handles the part of the water strategy that happens at the ground itself. Water that would otherwise sheet off a podium walkway or a driveway toward an already stretched drain moves instead through the surface and into the layer built to receive it. For a specifier weighing that surface against a formula like BWSSB’s, or whatever the next city’s version of it turns out to be, that is the difference between ground that works against the calculation and ground built to work with it.