PUB: Singapore's National Water Agency


Cost-Effective Rainfall Monitoring

How might we deploy a cost-effective solution to greatly increase the spatial coverage of rainfall monitoring?
Submission Deadline
up to SG$250,000


Singapore experiences an average of 167 rain days in a year, including 31 to 73 days classified as heavy rain days (based on 10 years of data). 

Today, PUB is relying on 81 units of rain gauges across 710 km2 of land area to monitor rainfall across the entire island. Due to World Meteorological Organization’s requirements as well as limited suitable sites for installing rain gauges, there will be locations where rain gauges are sited as far as 3-5km away from each other. This results in the problem whereby the nearest rain gauges are too far to give representative readings of the rain intensity in certain areas. 

Due to the convective nature of Singapore’s weather system, the rainfall in Singapore can vary significantly spatially and temporally. It is important that PUB obtains adequate rainfall data to support decisions to deploy flood management resources. The existing density of the rain gauge network does not provide enough resolution of the rainfall distribution and therefore, there have been instances in which the nearest rain gauge does not capture the actual rainfall at a location at a particular moment because it is sited outside the localised heavy rain area.

Challenge Owner: Catchment & Waterways Department, Drainage Planning Division

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Key Considerations and Challenges

  • The sensors must be appropriately sized (in terms of dimensions and weight) to be retrofitted to the top of public infrastructure such as lamp posts, bus stops, moving buses or HDB flats. Their weight shall not exceed the allowable designed loading on top of the infrastructure and in accordance with LTA or other relevant government requirements.
  • Each installation shall be approved by a professional engineer (Civil) with endorsed structural calculations as well as relevant government agencies.
  • The sensors must be self-powered and can be recharged using solar or renewable sources.
  • The sensor should ideally require minimal maintenance. The accuracy or functionality of the sensor must be minimally impacted when subjected to outdoor conditions, for example, falling leaves, bird droppings, extreme heat due to the sun, lightning.
  • The transmission of rainfall data must be done in real-time at 5-minute intervals from the onset of rain.
  • When drift in data accuracy is observed, rectification works should be carried out within 6 hours.
  • The sensors need to measure precipitation (mm) and transmit the data wirelessly in real time.
  • Proposed method statements for the calibration and preventive/corrective maintenance to ensure continuous operation of the sensors and the accuracy of the sensors, shall be provided. The method statements shall take into account safety considerations to access the sensors and to carry out the work.
  • The rainfall measurements provided by the sensor or proposed technology should be bench-marked with rain gauges for accuracy. This should be tested and verified according to a sound scientific methodology or certified by relevant Qualified Person.
  • The rainfall measurements provided by the sensor or proposed technology shall minimally achieve within +/- 15% of rainfall measurements provided by rain gauges

Current Technology Status

Existing Rain Gauge

  • Have stringent installation requirements which limits the number of suitable sites.

Use of AI/machine learning to estimate rainfall intensity from CCTV images

  • Already being explored by PUB to provide rainfall intensity estimation.
  • The number of CCTVs is limited, and it is not cost effective to install new CCTVs solely for the purpose of estimating rainfall intensity
  • Technology has limited applications in the evening/at night due to poor lighting conditions of the CCTV images


After selection

  • PUB will provide the preferred locations for deploying the sensors. Solution provider is to obtain all necessary agencies approval for the installation and maintenance of the sensors.
  • Data from rain gauges for validation and calibration purposes.

Expected Timeline

Total project period: less than 12 months
Solution development and deployment: up to 6 months
Solution testing and data analysis: up to 6 months

Expected Outcomes

An integrated system of cost-effective rain sensors that is validated through deployment and testing in a district in Singapore. The sensors should be mounted on appropriate public infrastructure such as lamp posts, bus stops, HDB flats, moving buses or any other suitable structures that the solution provider can propose. A dashboard interface developed by the solution provider shall provide a system overview and data visualisation of all deployed sensors in one dashboard. All sensors to be provided for this pilot including the customised web page for display of data shall be owned, operated and maintained by the solution provider. The solution provider will be responsible for obtaining the necessary approval from the relevant agencies. 

If the pilot is successful, the solution will be provided to PUB through a leasing model to which the solution provider is to provide an indicative pricing model.

Funding & Benefits


In order to support companies with innovative solutions to collaborate with PUB, we have lined up pilot funding, mentors, data, test sites, and other resources to support pilot projects.


Pilot Funding

PUB is committed to providing funding support to help cover the costs of development and test-bedding. This includes manpower, equipment and material costs. Shortlisted companies will receive initial funding of up to SG$250,000 for each pilot project.

Where the company already has basic technological components of the prototype or even a ready solution, the funding can be used to refine the solution based on the site requirements. The solution shall be developed to have systems and processes in place to support actual operations. By the end of the project, a system or process demonstration is carried out in an operational environment.

Where the company needs to perform activities involving design, development and controlled testing of technological components, the funding can be used for hardware and other development and testing. By the end of the prototyping phase, basic technological components shall be integrated to establish that they will work together. The resulting prototype is expected to have relatively “low fidelity” in comparison with the eventual system.

More information on the pilot requirements for each challenge is provided under Challe​nges​.

Upon being selected for funding through the PUB Global Innovation Challenge, companies can submit their funding request along with a detailed pilot proposal. The proposal and funding request will then be reviewed by PUB’s Project Evaluation Panel. More than one company per challenge could eventually receive the funding.

The awardees will be required to propose a payment schedule based on significant milestones, so that payment can be made progressively throughout the pilot project upon attainment of each milestone.

If the pilot project proves to be successful, the awardee will have access to additional funding for further development and testing, or contracts for deployment of the solution.

Mentorship by PUB Experts

If selected for the Pilot Phase, companies will be matched to relevant department(s) and receive mentorship from PUB’s experts. The companies will be able to leverage on their insights and past learnings to accelerate the development of their solution(s) for the water industry.

Test-bedding opportunities

For each of the challenges, PUB has prepared test sites, data and other internal resources so that solutions can be tested under real conditions and demonstrate valid results.

Commercialisation of Opportunities

If the pilot proves successful, PUB is best positioned to help commercialise and scale the product. The Singapore Water Exchange, which is run by PUB, houses entrepreneurs, startups, investors, accelerators, incubators, market advisors, technology providers, equipment suppliers, research institutes, system integrators and associations to support R&D and help companies build capabilities.

Terms & Conditions

PUB Global Innovation Challenge (the “Programme”) is organised by Public Utilities Board (“PUB”) Singapore and Padang & Co Pte Ltd, UEN No.: 201406957G (“Padang”) henceforth collectively known as “the Organisers”

​These Terms and Conditions (“T&C”) govern the Programme. Participation in the Programme constitutes acceptance of these Terms and Conditions as may be amended by the Organisers when required at the Organisers’ sole discretion.


“Deliverables”: jointly refers to the Application Questionnaire and the Application Deck.
“Participant”: refers to any company registered in accordance with the T&C who takes part in the Programme.


2.1. Participation in this Programme is free.
2.2. By participating in the Programme, the Participant will have read these T&C, and fully accepted their terms in their entirety without reservation.
2.3. Any Participant who does not abide by the terms of the T&C at any time during the Programme will be automatically disqualified from the Programme.


3.1. To apply for the Programme, the Participant must fill in a questionnaire (“Application Questionnaire”) on the Website on or before the 2359 hours Singapore time on 31 August 2021. (“Deadline”)
3.2. Any Application Questionnaire containing incomplete information will not be accepted as an application entry.
3.3. The Participant agrees to be contacted through email sent by the Organisers during their participation in the Programme. The Participant also agrees to be contacted by phone.


4.1. Deliverables must be sent in the requested format and be written in English. For the proposal, it must be submitted in DOC, DOCX or PDF format.
4.2. In case of difficulties or an inability to read the Deliverables, the relevant Participant will be notified and have the responsibility to re-submit it within 12 hours of the notification being sent out by the Organisers.
4.3. Each Participant undertakes that the content of the Deliverables, and any other additional document submitted for the purpose of the Programme, is produced by itself. If it is found that the content has been plagiarized, the Participant will be disqualified.
4.4. The use of photos or images must be free of copyright. In any case, the Organisers will not be held responsible for the use of documents on which third parties have rights.


5.1. After the Deadline, PUB will evaluate Participants based on their Deliverables and shortlisted Participants will be invited to a pitch interview. Based on the interview outcomes, companies will be nominated for pilot funding (“Nominees”).
5.2. The Nominees may be awarded up to S$250,000 of funding.
5.3. The Nominees or approved funding is not transferable, and their sale or exchange is forbidden.
5.4. The Nominees will be required to submit a detailed project proposal using the template provided by PUB, which includes a breakdown of the project cost and justification for the funding required from PUB. The proposal and fund request will then be subjected to review and approval by PUB’s Project Evaluation Panel. The Panel will also determine the final amount of approved funding. More than 1 Nominee per challenge could eventually receive the funding.
5.5. Components/items allowable for funding and disbursement of approved funds are subjected to PUB’s prevailing terms and conditions. In general, disbursement of the funding amount shall be based on the completion of project milestones, which shall be determined with and approved by PUB.
5.6. If the pilot is successful, additional funding/contracts could be provided to deploy and scale-up the implementation of the solutions.
5.7 The Participant is responsible for the payment of any applicable statutory taxes, including withholding tax, for work done in Singapore. Where withholding tax applies, the Organisers will withhold a percentage of the payment for manpower for remittance to the Inland Revenue Authority of Singapore (IRAS). For more information on withholding tax, please refer to this link:


6.1 By participating in this Programme, the Participant has consented to the disclosure of the Deliverables to the Organisers and persons associated with the Programme, and to the publication of information relating to the Deliverables on various media platforms, including social media platforms.
6.2 The Participant warrants that any and all of the copyright, patents, trademarks, design rights, know-how, and other intellectual property and proprietary rights subsisting in or used in connection with the Deliverables (“Intellectual Property Rights”) is and remain the sole property of the Participant.
6.3 The Participant shall indemnify, defend, and hold harmless the Organisers against any and all claims, suits, losses, damages, costs, fees, and expenses arising out of or in connection with the Intellectual Property Rights.
6.4 Nothing in these T&C constitute a license of the Intellectual Property Rights by the Participant to any of the Organisers.


7.1. The Participant authorizes the Organisers to reproduce their trademark and their registered business names free of charge on communication materials about the Programme, including, but not limited, to websites, email signatures, newsletters, press releases, posters or banners at trade fairs, and on various social media platforms.
7.2 The Participant agrees and consents to public disclosure and use of their company members’ name, image, audio, and video recording for publicity purposes without payment or compensation.

Article 8 – LIABILITY

8.1. The Organisers shall not be liable to the Participant for any loss, damage, cost or expense incurred or suffered by the Participant howsoever arising in connection with the Participant’s participation in the Programme, whether virtually via the website, or physically in person, and including but not limited to the disclosure and publication of the Deliverables in connection with the Programme.


9.1. Where the Participant has disclosed to the Organisers personal data of her/himself (where the Participant is a natural person) or of his representatives (where the Participant is a corporate entity), the Participant hereby gives his own consent, and confirms that he has obtained from such persons their consent to the collection, use and disclosure by the Organisers of such personal data, for example, as mentioned in Article 3.


10.1 The Organisers reserve the right to modify the T&C at any time, without prior notification to the Participant. The Participant is invited to read the T&C, which are published on the Website, on a regular basis.


11.1 The Organisers reserve the right to cancel, shorten, and suspend the Programme without prior notice.


12.1 Except with the written consent of the Organisers, the Participant shall not disclose any information issued or furnished by or on behalf of the Organisers in connection therewith to any person.
12.2 In addition to the foregoing, the Participant shall not make use of any information obtained directly or indirectly from the Organisers or compiled or generated by the Participant in the course of the Programme which pertains to or is derived from such information, other than use for the purposes of this Programme, without the prior written consent of the Organisers.


​ 13.1 The Organisers will disqualify the Participant if the Participant shall have offered or given or agreed to give to the Organiser or any person any gift or consideration of any kind as an inducement or reward for their participation in the Programme.


​​​14.1 These T&C are governed by and construed in accordance with Singapore law. The Organisers and the Participant submit to the exclusive jurisdiction of the Singapore courts.