Questions to Ask Before Hiring an ETP or STP Contractor

Before hiring an ETP or STP contractor, ask about proven plants of similar type and capacity, the design basis and treatability data behind the proposal, why the technology was chosen, how they will support pollution control board consents, what performance they will guarantee at commissioning, and who will operate and maintain the plant afterwards. The answers separate engineering partners from equipment sellers.

The questions below are grouped by stage. Each explains why it matters, what a good answer looks like and the red flags to watch for. A summary table follows.

Experience and references

1. Which plants of similar type and capacity have you delivered?

• Why it matters: Treating hotel sewage is different from treating dairy or pharma effluent, and a 50 KLD plant is different from a 2 MLD one.
• A good answer: specific named projects in your sector and capacity range, with location, technology and outcome.
• Red flags: only generic claims, no case studies, or projects in unrelated sectors.

2. Can I visit a running plant and speak to its operator?

• Why it matters: A site visit shows how the plant performs years after handover, not just on commissioning day.
• A good answer: a visit to an operating plant of similar type, with the operator available to answer questions.
• Red flags: only brochure photographs, or references who cannot be contacted.

Design basis and treatability

3. What design basis is the proposal built on?

• Why it matters: Every sizing decision flows from flow rate, peak factor and wastewater characteristics. A wrong basis means an undersized plant.
• A good answer: a written design basis listing average and peak flow, inlet parameters, outlet standard and reuse target, based on your data.
• Red flags: a capacity figure with no stated inlet parameters or peak flow.

4. Will you test our wastewater before finalising the design?

• Why it matters: Industrial effluent varies widely, and some streams resist biological treatment. Treatability testing catches this before money is spent.
• A good answer: sampling and lab analysis of your actual effluent, with treatability studies for difficult streams.
• Red flags: a design proposed without seeing or sampling the effluent.

Technology choice

5. Why this technology rather than the alternatives?

• Why it matters: MBR, MBBR, SBR, conventional activated sludge, RO and evaporation each suit different loads, spaces and reuse goals.
• A good answer: a comparison of at least two options against your space, outlet standard, reuse target, power cost and operating skill.
• Red flags: one technology offered for every site, or no explanation of the trade-offs.

6. What will the plant cost to run each year?

• Why it matters: Power, chemicals, membranes and labour can outweigh the purchase price over the plant's life.
• A good answer: estimated power per kilolitre, chemical consumption and replacement intervals for membranes and media.
• Red flags: silence on running costs, or a quote that compares only capital prices.

Compliance and consent support

7. Which outlet standard is the plant designed to meet?

• Why it matters: Your plant is judged against CPCB directions and State Pollution Control Board consent conditions, and your Consent to Operate may be stricter than the general standards. For STPs, the 2017 notification caps BOD at 30 mg/L, or 20 mg/L in metros, and the NGT and SPCBs may impose stricter limits.
• A good answer: a design that names the governing standard and your consent conditions, with margin below each limit.
• Red flags: a promise to meet "CPCB norms" with no parameters listed.

8. What will you provide for consent applications and inspections?

• Why it matters: Consents to Establish and to Operate need process descriptions, drawings and test reports.
• A good answer: a clear list of documents the contractor will supply and support at inspections.
• Red flags: treating approvals as entirely the owner's problem.

Commissioning and performance guarantee

9. What performance will you guarantee, and how will it be tested?

• Why it matters: Without a measurable guarantee, there is no recourse if the plant underperforms.
• A good answer: outlet parameters guaranteed at the design load, verified by third-party lab tests during a defined performance trial.
• Red flags: "the plant will work" with no parameters, test method or remedy.

10. What is included in commissioning and stabilisation?

• Why it matters: Biological plants take time to stabilise, and handover before then shifts risk to you.
• A good answer: a defined stabilisation period, seeding, operator training and handover only after passing performance tests.
• Red flags: handover on mechanical completion, before the biology has stabilised.

O&M, AMC and spares

11. Who will operate and maintain the plant after handover?

• Why it matters: Most plant failures come from poor operation, not poor design.
• A good answer: an AMC or full O&M option with defined staffing, response times, lab testing and reporting.
• Red flags: no after-sales service, or a vague promise to "send someone when needed".

12. How are spares and consumables supplied?

• Why it matters: A blower or pump waiting weeks for a part means an off-line plant and a compliance risk.
• A good answer: a recommended spares list, standard equipment makes and a local supply arrangement.
• Red flags: proprietary parts available only from the contractor with no stated lead time.

Commercial terms, including BOOT

13. What exactly is in scope, and what is excluded?

• Why it matters: Quotes often differ because one includes civil works, sludge handling or electrical work and another does not.
• A good answer: a line-item scope listing civil, mechanical, electrical, instrumentation, sludge handling and commissioning.
• Red flags: a single lump-sum figure with exclusions buried in the fine print.

14. Do you offer a BOOT or pay-per-use option?

• Why it matters: A BOOT contract replaces upfront capital with a fee per kilolitre treated, with the contractor responsible for performance.
• A good answer: BOOT terms of 10–20 years, typically 12–15, with the tariff, performance obligations and transfer terms written down.
• Red flags: a financing offer with no performance obligations attached.

Documentation and training

15. What documentation and training will we receive?

• Why it matters: Your team needs to run the plant, pass inspections and plan upgrades long after the project team leaves.
• A good answer: as-built drawings, an O&M manual, equipment datasheets, test reports and hands-on training for your operators.
• Red flags: drawings and manuals promised "later", or training limited to a single walkthrough.

Summary: questions, good answers and red flags

Navbharat Water publishes its delivered plants on the Projects page, with case studies giving capacity, location and outcome for each. To send your design basis and get a proposal, use the Get a Quote page.

Frequently asked questions

How many contractors should I get quotes from for an ETP or STP?

Three is a common number: enough to compare design approaches and prices, few enough to evaluate properly. Give every bidder the same design basis, including flow, wastewater characteristics, outlet standard and reuse target, so the quotes can be compared like for like.

Should I choose the lowest quote for an ETP or STP?

Not on price alone. A low quote often reflects an undersized design, missing scope such as sludge handling or civil works, or cheaper equipment with higher running costs. Compare total cost over the plant's life, including power, chemicals, spares and operation, and check that every quote meets the same outlet standard.

What documents should a contractor hand over at commissioning?

At minimum: as-built drawings, process and instrumentation diagrams, the operation and maintenance manual, equipment datasheets and warranties, commissioning and performance test reports, lab results and a recommended spares list. These are needed for consent renewals, inspections and future upgrades.

Does the contractor have to handle pollution control board approvals?

The consent is issued to the plant owner, but a good contractor supports the application with design documents, process descriptions and commissioning reports, and designs to the conditions in your Consent to Establish and Consent to Operate. Agree in the contract exactly which documents they will provide.

What is a BOOT contract for an ETP or STP?

Under BOOT, build-own-operate-transfer, the contractor finances, builds and operates the plant and you pay a fee per kilolitre treated. Terms typically run 10–20 years, most often 12–15, after which the plant transfers to you. It suits sites that want to avoid upfront capital and outsource operation.