Per-load quality proof so apartment STP surplus water can be sold to builders
TL;DR Batchmark turns the surplus water from apartment sewage plants into a product builders will buy. It tests each tanker load, issues a quality record the buyer can check, and books the transport. Apartments earn back part of their running cost, and builders get cheaper non-potable water with proof attached.
Bengaluru has more than 3,500 decentralised sewage plants, the most of any Indian city[1]. Rules from 2016 force larger apartment blocks to treat their own sewage, yet a pollution board official says even big complexes with lawns use only 40–50% of what they treat[2]. The water board's rough study put apartment output near 700 MLD, with half of it going down the drain[3].
The state allowed apartments to sell their surplus in 2024. A year later? Only a handful had found a buyer. The builders' body raised doubts about water quality, and transport costs ate the margin[1].
What it does, in regulatory terms: quality testing, record-keeping and logistics for non-potable treated water only. Batchmark never supplies water for drinking or bathing. The selling apartment's plant still runs under its own Karnataka State Pollution Control Board consent.
The seed pitched AI that tunes reuse inside one building. I reframed it, because the real waste sits outside the building. Most complexes already make more treated water than they can use, so the missing piece is a buyer who trusts it.
Batchmark fits a small sensor set at each seller's outlet (turbidity, pH, residual chlorine) and runs a quick field test on every load before it leaves. A partner lab checks a sample of loads each week. The buyer scans a code on the tanker and sees the readings for that load, the plant it came from and its recent record. Batchmark matches plants to sites within a short radius, so tanker trips stay short, and it takes a fee per kilolitre moved.
Builders and site contractors pay per load, and they are the main buyers of non-potable water in the city[1]. Apartment associations are the sellers. They pay nothing upfront and receive most of the sale price, which offsets plant running costs that one 2016 report put at ₹300–1,400 per household a month[4]. Tanker operators are paid per trip.
The 2024 state decision made the sale legal, and the water board signed an agreement with the Bangalore Apartments' Federation to help it along. The board itself said the trade stalled because there were no facilitator firms to link sellers and buyers[5]. Quality doubts remain the main objection, and the board has talked of bringing in IISc to certify water[1].
No public figure exists for the value of traded treated water. The narrowest estimate is the water board's: about half of roughly 700 MLD from apartment plants goes unused[3]. A 2026 study found reuse from decentralised plants still near 50%[6]. How much of that sits within a short drive of active building sites is the number to find first.
One Bengaluru tanker-booking app, founded in 2020, books tankers for fresh and treated water from a network of 1,800+ tankers and says it offers quality assurance[7]. The water board sells its own treated water to builders by tanker. Nobody I found publishes per-load test records from apartment plants, which is the doubt builders keep raising. A tanker platform could add this, so speed and lab partnerships matter.
| Difficulty | Moderate (38/100) |
| Starting capital | ₹55–95 L |
| Time to launch | 6–9 months |
The sensors are cheap. The hard part is trust on both sides - getting apartment committees to share plant data, and getting a builder's engineer to accept your record instead of their own test. Transport economics are tight, so the matching radius decides whether a load makes money.
Yes, a few rules apply, because you move treated sewage water between private sites.
Building this outside India? The categories above usually have a local equivalent, so check with your own regulator.
Don't trust AI to decide that water is fit for a use. Lab tests and the agreed limits decide that, and the water is never for drinking or bathing.
Want to work out the AI layer for Batchmark? Talk to Yash →
Here's what can go south -
I like this one if you have water-treatment or construction-procurement experience and you're happy running field operations. If you want to stay purely software then it's a poor fit. Before raising money, prove that one builder will take 30 tested loads in a month at a price that leaves a margin after transport.
Plan for roughly ₹55–95 L, mostly sensors, field testing, partner lab fees and logistics.
Each selling plant needs its pollution board consent, and Karnataka's rules on sale apply. Get the water board's guidelines in writing, and register for GST.
Yes, where reuse for construction is allowed. Check local reuse standards and who may sell treated water first.
The free Batchmark validation kit has the line-by-line capital breakdown, the effort scoring, the consent and testing checklist, a 14-day validation sprint with pass/fail targets, a 90-day launch plan, 10 interview questions for apartment committees and builders, and 5 assumptions to test. Download the kit →
Thinking about building Batchmark or something close to it? The make-or-break work is a testing routine that a builder's site engineer will accept without retesting, and that's the kind of thing I help founders work out. If you need a hand, you know where to find me. Talk to Yash →
For illustration only. Names are fictional and ideas hypothetical; sourced facts are real but may be out of date. Nothing here is legal, financial or professional advice, and Yash Khatri is not personally liable for any use of it. Read the full disclaimer.