What should you check before buying a green or eco-friendly apartment?

Last modified: 29 Oct 2026 • 6 min read

Direct answer: Ask for proof, not adjectives. A green apartment should show a working sewage treatment plant, rainwater harvesting, a stated water source, energy-saving common systems and, if it claims a rating, the certificate. Ask what each system costs residents to run every month. The RERA page and the approved plan show what was actually promised.

Verify with your CA: whether any part of the price or maintenance is billed with GST, and how a solar or common-area charge appears in your invoices.

Verify with your lawyer: that the green features are written into the agreement for sale with specifications, not just in the brochure.

"Eco-friendly", "green" and "sustainable" are now standard words in Bengaluru brochures. Some projects have real systems behind them; others have a few plants on the terrace. The checks below help you tell the difference and estimate what the systems will cost you after possession.

What makes an apartment "green" in practice?

Look for systems you can see and records you can read.

Sewage treatment plant (STP): treats wastewater on site so it can be reused for flushing and landscaping. Ask its capacity and who will run it. See our STP and borewell checks.
Rainwater harvesting: recharge pits or storage that the plan shows. Ask where the water goes.
Water source: municipal connection, borewell, tanker, or treated water. Read BWSSB connection for a new apartment.
Solar: rooftop panels for common areas, and whether they are connected to the grid. See solar rooftop in apartments.
Energy-saving common systems: LED common lighting, efficient lifts and pumps.
Waste handling: segregation and composting.
Rating: if the brochure claims a green building rating, ask for the certificate and the stage it covers (design or completed building).

How do you check a green claim?

Read the RERA page. On Karnataka RERA, the project's documents include the approved plan and the specifications the promoter filed. If an STP or solar system is not mentioned, ask why.

2. Ask for it in the agreement. Under the RERA Act, section 14 requires the promoter to build as per the approved plans and the specifications disclosed. Specifics in the agreement are easier to enforce than a brochure line.

3. Ask for the rating certificate, with the project name, phase and date. A "pre-certified" or "registered" status is not the same as a final rating.

4. Visit an older project by the same promoter. See if the STP runs, the solar panels are clean and the rainwater pits are maintained. Our page on assessing a builder's track record has a checklist.

What will the green systems cost you after possession?

Green systems save money only if someone runs them. Ask the promoter, and later the association, for the monthly cost of:

STP operation, power and testing;
solar panel cleaning and inverter maintenance;
water tanker top-ups in summer, if any.

These usually sit inside your maintenance charge. Our page on maintenance per square foot explains how that charge is built, and GST on maintenance covers when GST applies.

Worked example (illustrative figures). If a project's maintenance is quoted at ₹4 per square foot per month, a 1,200 sq ft flat pays ₹4,800 a month. Ask what share of that goes to the STP and water. If water tankers are a large part, the "green" saving may not be showing up yet.

How does water differ across East, North and South Bengaluru?

East Bengaluru: newer pockets in Varthur, Gunjur and along Sarjapur Road often depend on borewells and tankers until piped supply reaches them. A working STP and rainwater harvesting matter more here. Our Budigere Cross water note is one example of how to check.

North Bengaluru: similar issues in newer areas along the airport road and towards Devanahalli.

South Bengaluru: older areas closer to the city are more likely to have piped supply; newer projects further out on Kanakapura Road or beyond Electronic City may not.

In each case, ask residents of nearby buildings what they pay for water in April and May.

What should you ask the promoter about green features?

Is each feature in the agreement for sale? A brochure is not binding. Ask for solar panels, rainwater harvesting, the sewage treatment plant (STP) and EV charging to be listed in the specifications annexed to the agreement.

2. Who runs the systems after handover? STPs and solar systems need operators and annual contracts. Ask who pays and from when.

3. What is the STP capacity and where does treated water go? Treated water is often used for flushing and gardens. Ask whether flushing lines are separate.

4. Is there a green building rating, and at what stage? Some ratings are given at the design stage and others after completion. Ask which one the project has, and ask for the certificate.

5. How many EV charging points, and at whose cost? Ask whether owners can install a charger at their own parking slot and how it is metered.

What common mistakes do buyers make?

Paying extra for a "green" label without asking for the certificate.
Assuming rainwater harvesting means no water shortage. It helps recharge, but supply still depends on BWSSB, borewells or tankers.
Ignoring the running cost of an STP in the maintenance estimate.
Not checking whether common-area solar power is linked to the BESCOM connection. Ask the promoter how it is connected.

Checklist before you pay for a green apartment

Confirm the STP capacity and who will run it.
See the rainwater harvesting on the approved plan.
Ask the water source, and the tanker cost in summer.
Ask for the green rating certificate, if claimed, with stage and date.
Check the solar system's size and what it powers.
Get the green specifications written into the agreement.
Ask for the expected monthly maintenance and its breakdown.
Visit an older project by the same promoter.

Frequently asked questions

Is a green-rated apartment always cheaper to live in?

Not automatically. Savings depend on whether the STP, solar and water systems are run well. Ask current residents of the promoter's older projects what they pay each month.

Where can I check what the promoter promised?

On the project's Karnataka RERA page, which holds the approved plan and specifications, and in your agreement for sale. Ask for green features to be listed with specifications.

Does every apartment need an STP?

Larger projects are generally required to treat wastewater, but the rule depends on the project size and approvals. Ask to see the STP on the approved plan and the pollution control consent, if any.

Can rooftop solar cut my maintenance bill?

It can lower common-area power costs if the system is sized well and connected properly. Ask the size of the system, what it powers, and who maintains it.

Does an STP add to maintenance?

Yes. It needs power, an operator and regular servicing. Ask the promoter or the association for the monthly cost and include it in your budget.

Is a green building rating required by law?

Not generally for a home buyer's purchase. It is a voluntary rating. If a promoter claims one, ask for the certificate and its stage.

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References

PRS Legislative Research, "Real Estate (Regulation and Development) Act, 2016, full text", 2016 (sections 3, 4(2)(l)(D), 11, 13, 14(3), 18 and 19): https://prsindia.org/files/bills_acts/acts_parliament/2016/the-real-estate-(regulation-and-development)-act,-2016.pdf, accessed 29 Oct 2026.
Karnataka Real Estate Regulatory Authority, "Official portal: project search, quarterly updates, complaints": https://rera.karnataka.gov.in/, accessed 29 Oct 2026.
Bangalore Water Supply and Sewerage Board, "Official site": https://bwssb.karnataka.gov.in/, accessed 29 Oct 2026.
BESCOM, "Official site": https://bescom.karnataka.gov.in/, accessed 29 Oct 2026.

This page explains public rules and processes. It isn't legal or tax advice. acre&key gives buyers advice for free.