Enviro Infra Engineers is a water-treatment builder that has spent fifteen years turning sewage and industrial waste into reusable water for India’s cities and factories, and has now begun applying the same build-and-run playbook to solar, wind and battery storage. It started in 2009 by acquiring a Delhi partnership firm and grew project by project-from a single effluent plant in Rajasthan to a national order book of over ₹6,800 crores-by keeping design, civil construction and plant operations inside the company rather than farming them out. That in-house grip on execution is the recurring logic: bid accurately, build on time, and then stay on to operate the asset, whether it is a sewage plant in Uttar Pradesh or a battery storage project in Bihar.
Business segments
Two engines at different stages-a water-treatment cash cow built over a decade and a renewable-energy platform assembled rapidly through acquisitions-each earning from both construction and long-term operation.
1. Water and wastewater treatment: the founding infrastructure engine
The company designs, builds and runs treatment plants for government bodies, earning lump-sum construction fees upfront and recurring annuity or O&M income for up to fifteen years afterwards.
- Paid to build, then paid to run - under EPC contracts (about 70% of FY26 revenue) it earns a fixed lump sum for designing and commissioning a plant; under the Hybrid Annuity Model (about 13%) it gets milestone payments during construction plus regular annuity payments over a concession period that typically includes 15 years of operation; and under standalone O&M contracts (about 4%) it collects recurring fees for running and maintaining plants, covering everything from consumables to compliance.
- In-house execution from bid to commissioning - its own engineering team handles design and bidding, its own civil-construction crew builds on site, and a dedicated O&M team takes over once the plant is running, which reduces dependence on third parties and helps it deliver on time (one HAM project in Bareilly was completed more than two months early, earning a bonus).
- Zero Liquid Discharge is the standard, not the exception - the majority of its plants are ZLD-compliant, meaning treated water is reused for horticulture, industrial processes or washing rather than discharged, and it deploys technologies like Sequencing Batch Reactors, high-rate anaerobic digesters and membrane bioreactors to meet stringent pollution-board standards.
- Waste-to-energy bolted onto treatment plants - at several sites it installs solar panels for captive power and compressed-biogas units that turn sewage into fuel sold to oil-marketing companies, so the plant generates energy while treating water (seven of its 21 active projects as of FY25 included such sustainability components).
2. Renewable energy: the new platform built through acquisitions
The company entered solar, wind and battery storage in FY26 by buying specialist firms and project vehicles, and already holds a combined renewable order book of over ₹3,100 crores across EPC and IPP roles.
- Bought, not just built - it acquired a dedicated renewables subsidiary (EIE Renewables) and then purchased a string of project SPVs and operating companies: a solar developer (Sunaxis), a solar project (Soltrix), a 40 MW solar project in Odisha (Vento Power), a 150 MWh battery-storage project in Bihar (PRA Bihar Bess), and a wind-EPC firm with over 500 MW of completed projects (Suyog Urja), giving it immediate teams, order books and client relationships.
- Wind EPC runs on an asset-light, near-zero-debt model - the wind business, anchored by Suyog Urja, executes turnkey projects for AAA- or A-rated clients like Tata Power and Suzlon without tying up its own balance sheet in heavy equipment, and it brings an active execution pipeline of roughly 1,700 MW.
- First mover in India’s battery-storage build-out - it has already won four BESS projects from NTPC totalling 930 megawatt-hours across four states, plus a 150 MWh project in Bihar under a build-own-operate-transfer model with viability-gap funding and a 12-year fixed monthly tariff per megawatt.
- Solar plays both developer and contractor - it is building 79 MW of solar capacity under the IPP (independent power producer) model, where it owns the plant and sells the power, while also executing EPC contracts for third-party solar projects, so it earns from both asset ownership and construction services.
- A 250-person team led by industry veterans - the renewables division has dedicated business heads for solar, wind and BESS, and the Suyog Urja acquisition brought a 160-strong technical team whose erstwhile promoter is contracted to stay for at least three years, locking in the expertise that built over 1,200 MW of projects.
Group structure and partners
The parent company holds water-treatment project SPVs directly and channels all renewable-energy activity through its wholly owned subsidiary EIE Renewables, which in turn controls a chain of acquired project companies.
- In water, it incorporates a separate special-purpose vehicle for each large HAM or annuity project-such as the Bareilly, Mathura, Saharanpur and two Varanasi STP companies-and also enters joint ventures with other infrastructure firms to meet the technical and financial thresholds for specific government bids.
- In renewables, EIE Renewables sits as the holding company and owns Sunaxis (ground-mounted and floating solar), Soltrix (29 MW solar, Maharashtra), Vento Power (40 MW solar, Odisha), PRA Bihar Bess (150 MWh BESS, Bihar) and Suyog Urja (wind EPC, pan-India), with the remaining minority stakes in Soltrix, PRA Bihar Bess and Suyog Urja contracted for phased buyout over one to three years.