Bengaluru: In a move to upgrade sewage infrastructure, the Bengaluru Water Supply and Sewerage Board (BWSSB) is upgrading multiple rehabilitated sewage treatment plants (STPs) across the city. The focus is on enhancing the capacity and efficiency of existing STPs in both the East and West zones.Of 34 existing STPs, 20 have been taken up under the National Green Tribunal norms among which seven are at a cost of around Rs 33.4 crore and are expected to be completed by the end of this year.These rehabilitation projects cover plants in Shivajinagar, Mahadevapura, KR Puram and Dasarahalli with capacities ranging from 2 MLD to 60 MLD, with four in the East zone and three in the West zone. In the East, plants at Ulsoor (2 MLD), Kadugodi (6 MLD), K&C Valley (60 MLD) and Yellamapalya (15 MLD) are being upgraded, while in the West, STPs at Chikkabanavara (5 MLD), Seegehalli–K&C Valley (40 MLD) and Nagasandra (20 MLD) are under rehabilitation.Officials said the rehabilitation works include modernisation of old infrastructure, upgrading treatment processes and ensuring compliance with environmental standards.Ram Prasanth Manohar, Chairman, BWSSB said: “Rehabilitation essentially means upgrading older sewage treatment plants to meet the revised standards set by the National Green Tribunal in 2018. Earlier, the treated water BOD level was 20 mg/l, which has now been reduced to 10 mg/l. Similarly, COD has come down from 250 mg/l to 50 mg/l, while total nitrogen is now capped at 10 mg/l and total phosphorus at 1 mg/l. The pH range remains between 6.5 and 8.5. Since these norms are far more stringent than before, work has been taken up.”According to him, to meet these tighter parameters, they are adding a tertiary treatment stage to existing plants. “While the conventional system — primary clarifier, aeration tank and secondary clarifier — remains, an additional unit in the form of a disc filter is being installed. This acts as a physical filtration step before chlorination, significantly improving the final treated water quality. Since these are brownfield projects, upgrades are being carried out in phases without shutting down operations, which makes execution more challenging,” he added.More STPs to meet demand Alongside the rehabilitation works, BWSSB is also rolling out new STPs in the CE (Project) zone to cater to growing urban settlements. These new plants, located in areas such as Jakkur, Pillaganahalli, Thalagattapura, Hemmigepura, Sampigehalli and Nagasandra, range from 4 MLD to 13 MLD in capacity. Each project, costing between Rs 10 crore and Rs 39 crore, is designed to meet increasing sewage treatment demand in rapidly developing localities.The new STPs are expected to be operational by 2028, with progress already nearing 100% in some locations. Financially, these projects are also on track, with significant expenditure already made towards their completion.Officials said the inauguration of these plants will provide much-needed boost to Bengaluru’s sewage management, ensuring cleaner waterways and improved environmental compliance for the city’s expanding population.BOX: Sewage StatsAs per the Economic Survey of Karnataka 2025-26, as of March 2026, Bengaluru, with an urban population of nearly 1.5 crore, generates an estimated 1,480 million litres of sewage per day. The city is currently served by 34 STPs with a total installed capacity of 1,348.5 MLD. Of this, 1,212.7 MLD of wastewater is being treated at present, indicating a gap between sewage generation and treatment capacity. Box : Plants at present Drainage zoneCapacity in MLDNo. of STPsChallaghatta Valley518.59Koramangala Valley 2078Hebbal27811Vrishabhavathy3455Total1,348.534 Source: State Economic Survey 25-26
