A business in Singapore that discharges trade effluent needs written approval before the first drop leaves the premises. The authority depends on the destination. Discharge into the public sewer requires a Written Approval (WA) from PUB. Discharge into a watercourse or onto land requires written permission from NEA. PUB’s Trade Effluent Guidebook and NEA’s pollution control pages set out this split. This guide covers who applies, what the application contains, which limits apply, what the site must provide, and what non-compliance costs.
TL;DR
- Discharge to a public sewer needs prior written approval from PUB. Discharge to a watercourse or land needs written permission from NEA.
- The PUB Written Approval is valid for 5 years, carries no licence fee and has a 30-working-day processing target once documents are complete.
- Public sewer limits include BOD 400 mg/L, COD 600 mg/L, TSS 400 mg/L, pH 6 to 9 and a maximum of 45°C. Watercourse limits are stricter.
- The site must provide sampling points and any pre-treatment plant PUB requires, and must not tamper with them.
- First-conviction fines under the trade effluent regulations reach $15,000, with daily fines for continuing offences.
Table of Contents
- Which authority issues the permit
- How to apply for a PUB Written Approval
- Permission for discharge to a watercourse or land
- Discharge limits and prohibited substances
- Site requirements before discharge begins
- Duties after approval is granted
- Construction sites and temporary works
- Penalties for discharging without approval or breaching conditions
- Our perspective
- Getting the submission package ready
- Support from AEC Technical Advisory
- FAQ
- Sources
Which authority issues the permit
Two statutes govern the question, and the destination of the effluent decides which applies.
| Destination | Authority | Legal basis | Approval |
|---|---|---|---|
| Public sewerage system | PUB | Sewerage and Drainage Act and Sewerage and Drainage (Trade Effluent) Regulations | Written Approval |
| Watercourse (open drain, canal, river) or land | NEA | Environmental Protection and Management Act (EPMA) and EPM (Trade Effluent) Regulations | Written permission |
Under section 16(1) of the Sewerage and Drainage Act, no person may discharge trade effluent into a public sewerage system, or into a drain-line or sewer connected to one, without the prior written approval of PUB and outside that approval’s conditions, as the PUB Trade Effluent Guidebook records. Under section 15(1) of the EPMA, discharging trade effluent, oil, chemicals, sewage or other polluting matter into any drain or land without written permission from NEA’s Director-General is an offence.
In practice, most industrial premises with a sewer connection fall under PUB. NEA’s Pollution Control 1 Division administers the watercourse regime. The two approvals are not interchangeable. A site that holds one has no cover for a discharge of the other kind.
How to apply for a PUB Written Approval
The application is made through the GoBusiness Licensing Portal. The GoBusiness listing for the Written Approval states that the applicant must be an ACRA-registered company or business. It also lists the supporting documents:
- A laboratory test report of the effluent.
- A manufacturing process flow diagram showing where and how trade effluent is generated.
- A wastewater treatment process flow diagram.
- Licensed waste collection documents.
- Material safety data sheets (MSDS) for the chemicals used.
The same page lists the accepted file formats (xls, tif, ppt, doc, pdf and jpg) and a maximum upload of 2 MB per application. Large drawings and reports therefore need to be compressed or split sensibly before submission.
What the regulations require the applicant to disclose
Under regulation 4(2) of the Sewerage and Drainage (Trade Effluent) Regulations, the applicant must give PUB:
- particulars of the trade, manufacture, business or building construction;
- details of all processes or operations;
- particulars of all raw materials and chemicals used;
- the layout of machinery, plant and equipment;
- an estimate of the water consumed;
- the physical, organic and chemical nature of the trade effluent;
- any other information PUB may require.
Incomplete process descriptions are the usual reason for follow-up queries. The flow diagram, chemical list and laboratory report should describe the same process, with the same stream names and the same volumes.
Processing time, validity and fee
PUB aims to process permit applications, including this Written Approval, within 30 working days of receiving all required documents, according to its Trade Effluent FAQs. The clock starts only when the submission is complete. The GoBusiness page states that the WA is valid for 5 years and that no payment is required for the licence itself. Renewal should be planned well before expiry, with updated test results and process documents.
Permission for discharge to a watercourse or land
NEA’s service standard for written permission covering use of scheduled premises and discharge of trade effluent into a watercourse is 30 working days, as shown on its Service Standards page. Where a project involves wider pollution control approvals for scheduled premises, the staged process is explained in our guide to pollution control approval in Singapore.
Discharge limits and prohibited substances
Approval is granted against numerical limits. Exceeding them is an offence even when a permit is in force.
Public sewer limits
Regulation 10(1) of the Trade Effluent Regulations prohibits discharge to a public sewer above these values:
| Parameter | Maximum |
|---|---|
| BOD (5 days at 20°C) | 400 mg/L |
| COD | 600 mg/L |
| Total suspended solids (TSS) | 400 mg/L |
| Grease and oil (non-hydrocarbon) | 300 mg/L |
| Temperature | 45°C |
| pH | Not below 6, not above 9 |
| Caustic alkalinity | 2,000 mg/L as calcium carbonate |
The PUB Trade Effluent Guidebook lists the temperature, pH and alkalinity limits in its Annex D. Regulation 9 also lists substances that must never enter the sewer, including calcium carbide, petroleum spirit and other inflammable substances, radioactive material, blood waste and infectious waste. The July 2024 amendments expanded the list of prohibited compounds to cover those that may disrupt NEWater production.
Watercourse limits
NEA’s allowable limits are tighter because the effluent does not pass through a treatment works first.
| Parameter | Watercourse | Controlled watercourse |
|---|---|---|
| BOD (5 days at 20°C) | 50 mg/L | 20 mg/L |
| COD | 100 mg/L | 60 mg/L |
| TSS | 50 mg/L | 30 mg/L |
| pH | 6 to 9 | 6 to 9 |
| Temperature | 45°C | 45°C |
NEA also bars radioactive material, refuse, sawdust, solid matter, petroleum or other inflammable solvent, and substances that may give rise to hazardous gas, fume or odour.
When treatment on site is not feasible
The PUB guidebook notes that a company unable to provide a wastewater treatment plant, for example because of space constraints, or to engage a licensed waste collector in order to meet the BOD or TSS limits, may apply under the Trade Effluent Fee (TEF) Scheme. On approval, fees are paid for discharge in accordance with the scale in the regulations. This is an application in its own right, not a default.
Site requirements before discharge begins
Approval depends on physical provisions at the premises, and these are design matters that belong in the building drawings, not afterthoughts.
- Sampling and inspection apparatus. Under regulation 5 of the Trade Effluent Regulations, PUB may require sampling test points, inspection chambers, measuring devices and other apparatus. Since 1 July 2024, regulation 5(3) also prohibits tampering with them or with a pre-treatment plant.
- Pre-treatment plant. Where PUB requires one, it must be installed, used to treat the effluent before discharge and kept in efficient condition.
- Sampling sump. The PUB Code of Practice on Sewerage and Sanitary Works (3rd edition, March 2025) requires every industrial premises, whether on its own lot or in a flatted factory, to provide a sampling sump. A flatted factory with a common treatment plant provides it after the plant, before the discharge reaches an inspection chamber connected to the public sewer.
The sewer connection itself is a separate approval track. The sequence of steps for a Qualified Person is covered in our notes on PUB sewer connections and the PUB drainage requirements.
Duties after approval is granted
Holding a Written Approval does not end the obligations. Four recur.
- Notify changes. Regulation 4(4) requires written notice to PUB within 14 days of specified changes that affect the amount or nature of the effluent. PUB’s requirements document likewise calls for written notice within 14 days of a change to the company name, address, or the process or operation used.
- Maintain treatment facilities in good order so that the effluent complies with the regulations.
- Keep records. Under regulation 7, PUB may require particulars and records, including inspection and maintenance records, accredited laboratory results and toxic industrial waste disposal records, covering up to 12 months before the request.
- Test the right parameters. The guidebook advises that BOD, COD and TSS are the general baseline, with trade-specific parameters added, such as copper for an electroplating facility.
Under section 15(3) of the EPMA, anyone who causes or allows polluting matter to enter a drain or land without permission, even by accident, must immediately inform the Director-General. Failure is punishable by a fine of up to $5,000.
Monitoring is continuous on PUB’s side. According to Smart Water Magazine, PUB runs more than 150 microbial electrochemical sensors for heavy metals and cyanide and over 100 remote units for volatile organic compounds in the sewer network. Unreported excursions are therefore likely to be detected.
Construction sites and temporary works
Construction sites generate sanitary used water rather than process effluent, but PUB still controls the route. According to PUB’s Frequently Asked Questions on Used Water:
- Where a public sewer is accessible, temporary toilets and sanitary facilities must discharge into it, and no temporary used water tank is allowed.
- A temporary holding tank is permitted only where there is a technical constraint on connecting, or where no public sewer is available.
- The Qualified Person in charge of temporary works submits the environmental health plans for temporary toilets to NEA’s Central Building Plan Department for registration and a Clearance Certificate. That certificate goes to PUB with Form E, the application to connect the temporary facilities to the sewerage system.
Excavation near existing sewers adds its own conditions, which we cover in settlement monitoring and PUB sewer rules before excavation.
Penalties for discharging without approval or breaching conditions
The consequences are set out in statute and enforced.
| Offence | First conviction | Repeat conviction |
|---|---|---|
| Breach of regulations 8(1), 9(1), 9A(1), 10(1)(a) to (d) or (3), or 11(2) of the Trade Effluent Regulations | Fine up to $15,000, up to 3 months’ imprisonment, or both; further fine up to $500 per day if continuing | Fine up to $30,000, up to 3 months’ imprisonment, or both; further fine up to $1,000 per day if continuing |
| Failure to treat effluent as prescribed before discharge to drain or land (EPMA section 16(3)) | Fine up to $20,000, up to 3 months’ imprisonment, or both | Fine up to $50,000, up to 3 months’ imprisonment, or both |
The figures come from regulation 14(2) of the Trade Effluent Regulations and section 16(3) of the EPMA. Beyond fines, PUB states it can issue stop work orders and revoke approvals, per Smart Water Magazine. The same report records that from 2017 to 2023 PUB prosecuted 90 offenders for 295 trade effluent offences, and that around 70% of those prosecuted each year were repeat offenders.
Our perspective
Trade effluent approval is rarely the hardest part of a project. It becomes the hardest part when it is raised late. The sampling sump, the pre-treatment plant and the inspection chambers are physical items, and each one occupies floor area and sits on a drainage layout. If they are not in the design before the authority submissions go in, the fix is rework.
We treat the discharge route as a design input. The questions come early: where the effluent is generated, which authority governs the destination, what the process flow diagram will say, and whether the layout leaves space for the treatment and sampling provisions the regulations anticipate.
Our work covers statutory authority submissions, PE and QP endorsement, and the engineering design that sits behind them. That lets us align drainage, structural and temporary works drawings with the approvals a project needs, and keep the submission packages consistent with one another. Consistency is what shortens queries.
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Getting the submission package ready
Developers, factory owners and their consultants can reduce rework by settling the following before submission:
- Confirm the discharge destination: public sewer, watercourse or land.
- Confirm the applicant entity is registered with ACRA.
- Obtain a laboratory test report that covers the parameters relevant to the trade, not only BOD, COD and TSS.
- Prepare process and treatment flow diagrams that match the chemical list and MSDS.
- Arrange licensed waste collection for any stream that is not discharged.
- Show the sampling sump and inspection chambers on the drainage layout.
- Keep file sizes within the portal limit.
The approvals around the permit follow their own order. Our guide to PUB sewer connection approval and the note on obtaining PUB drainage clearance explain how they fit together.
Support from AEC Technical Advisory
AEC Technical Advisory provides engineering design and statutory authority submissions in Singapore, including PE endorsement and temporary works design, for developers, construction firms, architectural practices and building owners. Where a project needs drainage and sewer layouts, endorsements and authority submissions coordinated, our team can manage that package.
See the full list of services or review our PE endorsement and authority submission services.
FAQ
Does a business need a permit if it discharges only into the public sewer?
Yes. Section 16(1) of the Sewerage and Drainage Act requires PUB’s prior written approval for any trade effluent entering a public sewerage system. The approval is a Written Approval, applied for through the GoBusiness Licensing Portal, and its conditions bind the discharger.
How long does a PUB Written Approval last, and what does it cost?
The GoBusiness listing states a validity of 5 years and no payment for the licence itself. PUB aims to process complete applications within 30 working days. Costs for laboratory testing, treatment plant works or consultants are separate, and fees under the Trade Effluent Fee Scheme apply only where that scheme is approved.
What is the difference between PUB and NEA approval?
PUB approves discharge into the public sewerage system. NEA gives written permission for discharge into watercourses or land under the EPMA. The limits differ: a watercourse allows BOD of 50 mg/L, against 400 mg/L for a public sewer, because sewer effluent receives further treatment.
Must changes to the process be reported?
Yes. PUB requires written notice within 14 days of changes that affect the amount or nature of the effluent, and of changes to the company name, address or process. PUB may also call for up to 12 months of records on request.
What happens if a discharge exceeds the limits?
Exceeding a limit such as BOD, COD or TSS is an offence under regulation 10. A first conviction can bring a fine of up to $15,000, imprisonment of up to 3 months, or both, plus daily fines if the breach continues. PUB can also revoke the approval.
Sources
- PUB Trade Effluent Guidebook, 2nd edition
- NEA, Keeping Our Water Clean
- Environmental Protection and Management Act 1999, Singapore Statutes Online
- Sewerage and Drainage (Trade Effluent) Regulations, Singapore Statutes Online
- GoBusiness: Written Approval for the Discharge of Trade Effluent into the Public Sewer
- PUB Trade Effluent FAQs
- NEA Service Standards
- NEA Allowable Limits for Trade Effluent Discharge
- PUB Code of Practice on Sewerage and Sanitary Works, 3rd edition
- PUB Requirements for Discharge of Trade Effluent into the Public Sewers
- PUB Frequently Asked Questions on Used Water
- Smart Water Magazine: Safeguarding Singapore’s NEWater production