Bengaluru lake buffer and rajakaluve map for homebuyers (2026)

The files behind the map are public. Tanks and drains come from KSRSAC layers republished by OpenCity. The lake points come from a BBMP list. The coloured bands are a geometry we calculated from those drain lines and from the widths recorded in the Supreme Court judgment. They are not a surveyed revenue boundary.

Downloads: GeoJSON, BBMP lake points (CSV), named KSRSAC tanks (CSV).

What each layer is

Primary features store a field named SHAPE_Leng. The sum of that field, rounded to two decimal places, is 328,464.92. On the first feature the stored value is 7,536.37574677, and the same line measures 7,536.38 m in UTM zone 43N, which is why the field is read as metres. Secondary features store Shape_Leng. That sum, rounded the same way, is 438,813.98.

Tertiary drains are not on this map. The OpenCity file for them is a separate KML of about 25 MB. The judgment records a 15 m tertiary buffer from the middle. The file is linked from the stormwater drains dataset.

Some KSRSAC names are repeated on different polygons, including Hoskote Kere and Thattekere. The table keeps the object id so those rows stay distinct. The centroid is the representative point of the simplified outline, not a revenue-survey stone.

Which buffer applies after the Supreme Court and the 2026 Act?

Two different rules are in play, and they were set by different instruments.

Lakes and tanks. Karnataka Act 19 of 2026 amends section 12 of the Karnataka Tank Conservation and Development Authority Act, 2014. It was published in the Karnataka Gazette Extraordinary on 18 Feb 2026, received the Governor's assent on 16 Feb 2026, and came into force at once. The substituted section 12(3) bars construction and commercial, recreational or industrial activity inside the buffer in the table, measured from the revenue boundary of the tank. The exception is approved public utilities (roads, bridges, electrical lines, water-supply lines, underground drainage, a jack well or pump house, an STP, an ISPS, a wet well, an aqueduct and allied works) with the Authority's prior approval, and without blocking inflow or outflow. A further clause says the state pollution board's siting guidelines for new industries prevail over that clause for those industries.

Source: the table in Karnataka Act 19 of 2026. The gazette copy on OpenCity and the bill as passed carry the same table.

Drains. On 5 Mar 2019, in Mantri Techzone Pvt. Ltd. v. Forward Foundation, the Supreme Court set aside direction No. (1) of the National Green Tribunal's order of 4 May 2016, except the direction issued against respondent Nos. 9 and 10. That NGT direction had required 75 m from the periphery of lakes, 50 m from the edge of primary rajakaluves, 35 m from the edge of secondary rajakaluves and 25 m from the edge of tertiary rajakaluves, as a general rule. The judgment records what RMP-2015 itself provided: 50 m from the middle of a primary rajakaluve, 25 m from the middle of a secondary, and 15 m from the middle of a tertiary, set against a 30 m lake buffer in the master plan.

The 2026 Act rewrites the tank buffer. Its text does not rewrite the drain buffers. The bands on this map follow the RMP widths as the judgment records them: 50 m and 25 m either side of the mapped line, which is the "from the middle" reading. A line on a map is not the surveyed edge of a drain. If a building sits near the band, the approved plan and a lawyer decide whether the measurement is from the middle or the edge.

The NGT took suo motu notice of the state's move to reduce lake buffers and issued notices on 8 Aug 2025, before Act 19 of 2026 was notified (The Indian Express). In the sources read for this page, that report does not show a citywide stay of the Act. A later order can still change the answer for one lake. Ask a lawyer to check the lake you are buying beside.

Our lake and rajakaluve checklist walks through the same rules with worked examples. The flood-prone points page is a different list: road points that flood, not a buffer line.

Why the map does not colour a lake buffer

Act 19 of 2026 measures the lake buffer from the revenue boundary, and the width depends on area in acres from the revenue record. The KSRSAC polygon is a mapped tank outline. The BBMP row is a point. Neither file contains the revenue area or the revenue boundary.

The KSRSAC file does contain a shape-area number. Using that number to pick a row in the Act's table would treat a mapped outline as the revenue extent. This page does not do that. A lake can still be looked up by name, and the area has to come from the RTC.

For a named tank, the practical path is: find it on the map, note the name and the object id, then pull the survey extent from Bhoomi and the lake survey map on Revenue Maps Online. The same portal has rajakaluve survey details.

How to check a plot or project

Use the map to see whether a tank or a primary or secondary drain is near the site. Then leave the map. The steps below are the ones that produce a document a lawyer can read.

Find the tank or drain on this map

Search the BBMP table or the named-tank table for the water body you were shown. If it is there, note the latitude and longitude, or the object id. If the site is in an area with no named tank, turn the drain layers on and see whether a primary or secondary line passes the block. A miss on this map is not a clearance. The files do not cover every drain outside the former BBMP extent, and unnamed tanks are drawn but not listed by name.

Get the revenue area and the revenue boundary

Ask for the tank's survey number and the area in acres from the RTC. The buffer row in the 2026 table is meaningless without that area. The distance that matters is from the revenue boundary, not from the water's edge on a phone map.

Read the buffer off the 2026 table

Match the acre figure to one row. Write down the metres. If the plan was approved before 18 Feb 2026, ask which buffer the approval used. The master plan figure recorded in the 2019 judgment was 30 m around lakes. The Act now uses the size table. Which one binds an older approval is a legal question, not a map question.

Ask for the drain on the approved plan

For a rajakaluve, ask the builder or the seller to mark the primary, secondary or tertiary drain and the buffer line on the sanctioned plan. Compare that sheet with the primary and secondary lines here. This map's band is 50 m or 25 m from the KSRSAC line. The plan may measure from the edge. Those are different lines.

Pull the survey sheets

Lake survey maps and rajakaluve survey details are on Revenue Maps Online, by district, taluk, hobli and village. A layout brochure is not one of those sheets.

Walk the site after heavy rain

The buffer is a building line. It does not say whether the basement took water last monsoon. Look at the ramp, the plinth and the road you would actually use. Our flood-points page is the list of vulnerable spots, where a spot has been published.

Stop if nobody can show the boundary

If there is no RTC area, no survey sheet and no buffer line on the sanctioned plan, do not treat the colour on this map as a yes. The legal checks guide is the longer paper list. The buffer question still goes to a property lawyer before any token.

BBMP lake points

The name in the source file sometimes ends with a zone, written with an older English name of the city. This table splits that suffix off. The zone column is Central, North, South, East, North Additional, or East taluk. Fifty-five rows had such a suffix. The other 152 did not, so the zone cell is empty. The CSV column source_name keeps the field exactly as stored.

One hundred and thirty-eight coordinate strings in the file had lost the N or E letter to a bad character. Those were read as north or east because every latitude in the file is 12 or 13 degrees and every longitude is 77 or 78 degrees. Strings that still had the letter were read from the letter. Mangammanahalli lake and Kenchanapura lake have no coordinate in the file.

Named tanks in the KSRSAC layer

One hundred and seventy-three polygons have a name. The other tank polygons are on the map and in the GeoJSON, without a name to list. Centroid latitude and longitude are the representative point of the simplified outline.

Lawyer note: Buffer widths, the revenue boundary, and whether an older approval still stands are legal questions. This page is general information, not advice on a particular plot or project. Consult a property lawyer before you pay, sign or register.

Sources

Checked 20 Oct 2026.

1. Karnataka Act 19 of 2026, Karnataka Tank Conservation and Development Authority (Amendment) Act, 2025, Gazette Extraordinary, 18 Feb 2026 (copy hosted by OpenCity): https://data.opencity.in/dataset/2a2c0701-853e-4db3-b1d4-06ee8674c628/resource/ffff8ed9-228d-42a2-a596-3b4c06a8d726/download/lake-tank-buffer.pdf
2. The same amendment as passed by the legislature: https://kla.kar.nic.in/council/house/bills/156/33E.pdf
3. Supreme Court judgment, 5 Mar 2019, Mantri Techzone Pvt. Ltd. v. Forward Foundation: https://api.sci.gov.in/supremecourt/2016/16740/16740_2016_Judgement_05-Mar-2019.pdf
4. The Indian Express, NGT notices on the buffer reduction, 8 Aug 2025: https://indianexpress.com/article/cities/bangalore/ngt-takes-suo-motu-cognisance-of-buffer-zone-reduction-around-lakes-karnataka-10213014/
5. KSRSAC tanks for Bengaluru Urban, via OpenCity: https://data.opencity.in/dataset/lakes-and-ponds-in-bengaluru-district
6. KSRSAC primary and secondary stormwater drains, via OpenCity: https://data.opencity.in/dataset/bengaluru-stormwater-drains-maps
7. BBMP lake points, via OpenCity, source portal https://lms.bbmpgov.in/lake : https://data.opencity.in/dataset/bbmp-lakes
8. Bhoomi land records: https://landrecords.karnataka.gov.in/
9. Survey Settlement and Land Records, Revenue Maps Online: https://landrecords.karnataka.gov.in/service3/
10. OpenStreetMap tile copyright: https://www.openstreetmap.org/copyright