Trade effluent refers to any liquid, including particles of matter and other substances suspended in the liquid, that is the outflow from any trade, business or manufacture or of any works of engineering or building construction.

Premises which discharge trade effluent into the public sewerage system are required to obtain a Written Approval (WA) from PUB. The WA specifies the conditions that you must comply with if you want to discharge trade effluent into the sewers. You can apply for a WA online at https://www.gobusiness.gov.sg

You are responsible for ensuring your trade effluent is collected and disposed of responsibly. Do remember that discharging trade effluent into a sewer without approval from PUB or discharging non-compliant trade effluent into public sewers is a violation of the Sewerage and Drainage Act (SDA) and is illegal. As a business operator, you have a duty to ensure that any waste you generate is handled safely and in accordance with all environmental legislations.

The discharge of wastewater into open drains, canals, rivers and open sea is regulated by the Environmental Protection and Management Act (EPMA) and Environmental Protection and Management (Trade Effluent) Regulations. The EPMA and its regulations are administered by NEA. For more information you may visit NEA’s website at https://www.nea.gov.sg/

Businesses are required to inform PUB in the following scenarios:
a)   Change in company’s name, address, process or operation
b)   Change in plant layout or machinery, which affects the amount or nature of trade effluent discharged
c)   Change in company’s status e.g. from sole proprietor to private limited
d)   Company has ceased operations

Written Approvals have a validity period of 5 years upon issuance. Please ensure your Written Approval is valid and re-apply for a new Written Approval at least 3 months before the existing one lapses.

All trade effluent discharged into public sewers must comply with the discharge limits stipulated in the Sewerage and Drainage (Trade Effluent) Regulations.

If you are not able to meet the water quality discharge requirements, you can either:
a)   Install a wastewater treatment facility in your premises to pre-treat the non-compliant trade effluent so that the water quality parameters are within the acceptable limits, or
b)   Engage a licensed waste collector to collect and dispose your trade effluent off-site.

The handling of toxic industrial wastes is regulated by the Environmental Public Health Act (EPHA), governed by the National Environmental Agency (NEA). Under the EPHA, you need to engage a licensed toxic waste collector to collect and dispose of your toxic waste off-site. You will also need to properly account for all your waste generation. You may also be required to declare your waste disposal through NEA’s e-consignment system. For more information on the proper handling of toxic industrial wastes, please refer to the NEA’s website at www.nea.gov.sg. You should not engage a General Waste Collector to collect your toxic industrial wastes.

You may apply for permission to discharge the trade effluent under the “Trade Effluent Fee Scheme”. Under this scheme, upon approval from PUB, you will pay fees for the discharge of such trade effluent into public sewers. The fees payable shall be in accordance with the scale set out in Annex B. However, approval will not be granted for the discharge of trade effluent which contains:
a)   BOD greater than 6,000 mg/l of the trade effluent, or
b)   TSS greater than 6,000 mg/l of the trade effluent, or
c)   COD greater than 10,000 mg/l of the trade effluent or three times the concentration of BOD in the trade effluent, whichever is the lower.

If you know or suspect that there is an accidental discharge or non-compliant trade effluent being discharged into the sewers, please inform us as soon as possible. You can contact us through PUB-ONE, our 24-hour toll free hotline at 1800-CALL-PUB (1800-2255-782).

Here are some practical and simple tips you can follow to avoid accidentally discharging any illegal trade effluent:
a)   Ensure that your sanitary drainage plan is updated and clearly identifies the locations and flow of all existing drains and sewers around your premises.
b)   Maintain your pre-treatment plant to ensure proper treatment of trade effluent. Examples of common pre-treatment plants include oil interceptors and pH neutralizing systems.
c)   Clearly demarcate and familiarise yourself where the discharge points for collection of spent solvents for disposal by licensed waste collectors. When discharging trade effluent, check that you are connected to the correct system.
d)   Store and handle raw materials, wastes, chemicals, and fuels responsibly so that they do not enter the sanitary drain-lines, floor traps and sewers on your premises.
e)   Spill kits or absorbent granules/sawdust should be readily available at locations where there is a risk of spillage or leakage of pollutants into sewers. Ensure employees know where they are and how to use them.
f)   Do not wash spilled chemicals down the sewer or drain.
g)   Ensure that all relevant employees and contractors are familiar and comply with your procedures for handling, disposing and discharging liquid wastes.
h)   Explore possibilities for using alternative materials and practices.

If you have a pre-treatment plant in your facility, a maintenance schedule is essential to ensure that the plant is operating properly and treating your trade effluent adequately. You may refer to your operation manuals or contact your consultant, vendor, contractor to plan a comprehensive inspection and maintenance schedule.

Here are some useful tips:
a)   Keep records of all the servicing and calibration intervals of all the process instruments used in the wastewater treatment plant.
b)   Implement a servicing schedule for tasks including thorough inspection of the equipment and replacement of any consumable parts on a regular basis.
c)   Keep proper records of the mechanical components such as the pumps and stirrers in the wastewater treatment plant.

Together with a maintenance schedule, a process monitoring schedule effectively monitors the performance of your treatment process.

Here are some useful pointers: -
a)   Implement a schedule to regularly collect trade effluent samples from the pre-treatment plant and check that the treatment complies with the discharge limits as stipulated in the SD(TE)R. You may use commercially available analytical kits such as colorimetric tests.
b)   From time to time, collect and send trade effluent samples to an external accredited laboratory for accurate analysis.
c)   Keep records of all test results, monitor for any process trends, and revise the maintenance and monitoring schedules accordingly.

Here are some useful pointers:
a)   An oil interceptor has to be maintained regularly so that it can continue to treat trade effluent properly. You should implement a maintenance schedule which requires regular checks for:
      (i)   Excessive build-up of scum and debris which may get carried into the public sewers
      (ii)   Build-up of oil stains on the walls of the interceptor, and
      (iii)   Sufficient water level in the interceptor
b)   You are encouraged to implement a monitoring schedule to regularly check the quality of the trade effluent discharged from oil interceptors. Trade effluent samples may be collected from the outlet of an interceptor and sent to accredited laboratories for two tests: “Oil-and-Grease (Total)” and “Oil-and-Grease (Hydrocarbon)”. If you operate a motor-shop or trade that involves the use of industrial solvents such as metal degreasers, you are encouraged to send your trade effluent samples for “Gas Chromatographic Mass Spectrometry (GCMS)” analysis to detect for inflammable substances. Such laboratorial tests are useful for you to review your maintenance schedule of the oil interceptor.
c)   The collection, transportation and disposal of toxic wastes such as waste oil and spent solvents are regulated by the Environmental Public Health (Toxic Industrial Waste) Regulations, administrated by the National Environmental Agency (NEA).
d)   An oil interceptor needs to be cleaned periodically. The recommended steps for cleaning oil interceptors are as follows:

The sample that you collect for analysis should be representative of the trade effluent from your trade premise.
a)   If the trade premise has a pre-treatment plant, samples should be collected at the sampling tank or sump of the pre-treatment plant.
b)   If the trade premise does not have a pre-treatment plant, samples should be collected at the last inspection chamber of the trade premise.

The parameters or the pollutants to test depend on the trade you are in. For instance, if you are operating an electroplating facility that deals with copper plating, the pollutants that you should be testing for are the heavy metals such as copper if you are involved in copper plating. For a full list of parameters and discharge limits, you may refer to the Sewerage and Drainage (Trade Effluent) Regulations.

You can send your samples to an accredited laboratory for analysis. For more information, please visit the Singapore Accreditation Council (SAC) website at https://www.sac-accreditation.gov.sg

You may refer to the Sewerage and Drainage Act and Sewerage and Drainage (Trade Effluent) Regulations here.

Alternatively, to speak to a PUB officer regarding the discharge of trade effluent into the public sewers, please contact: PUB-ONE (24-hour toll free hotline) at 1800-2255-782.