Interactive Calculator · 2026
Green Building Water Score Calculator
Rate a building's water efficiency on a 0–100 scale. Set four levers — treated-water reuse, rainwater harvesting, low-flow fixtures and metering — for an IGBC/GRIHA-style score and rating.
Points each lever contributes to the 100-point score
Your building's water measures
Share of water demand met by recycled/treated water. Weight: 35 pts.
Share of roof/site runoff captured and used or recharged. Weight: 25 pts.
Share of taps, showers and WCs that are water-efficient. Weight: 25 pts.
Sub-metering and leak monitoring in place. Weight: 15 pts.
Where your points come from
Each lever's current contribution to the 58-point score — the shortest bar is your fastest win.
Treated-water reuse carries the most weight (35 pts), so it usually moves the score fastest — followed by rainwater harvesting and low-flow fixtures at 25 pts each.
Metering & monitoring is a flat 15-point prerequisite: cheap to add and the single easiest bump when it's missing.
How this is calculated
- Reuse = 50% × 0.35 = 17.5 pts · Rainwater = 40% × 0.25 = 10 pts.
- Fixtures = 60% × 0.25 = 15 pts · Metering = Yes → 15 pts.
- Score = 17.5 + 10 + 15 + 15 = 58 / 100 → Silver.
Indicative, IGBC/GRIHA-inspired scoring for early design conversations — a formal rating audits actual consumption, plumbing and documentation. Confirm with a certified green-building consultant.
Related Guides — Deep-dive reading
Green Building Water Credits: How STPs Earn Points Under IGBC, GRIHA & LEED
How on-site sewage treatment and water reuse convert into rating-system points — the water-efficiency credit categories under IGBC, GRIHA and LEED, the evidence assessors ask for, and exactly where an STP moves the needle.
Sewage Treatment PlantsCircular Water Management for Buildings & Cities: The Closed-Loop Guide
How to stop treating water as a one-way flow and design a closed loop — treat, reuse, recharge, repeat — with a sewage treatment plant at its core, for Indian buildings, campuses and cities.
Sewage Treatment PlantsSustainable Home Design in India
A Practical Guide to Climate, Craft, and Conscience in the Indian Home
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