The History of Water Quality in Singapore: Talking about Science from a Historical Perspective (or is it History from a Scientific Perspective)

[Appended in March 2024: The experience in 2023 had been so positive that I returned in March 2024 to give another round of training to the latest batch of docents of the National Museum of Singapore. The session was conducted more like a discussion rather than a lecture. This is one of my preferred modes of "training" for adult learners.]

 

I recently (March 2023) had the privilege to be invited to provide a training session to the docents of the National Museum of Singapore. The topic was on the history of water quality in Singapore. Admittedly, history has never been my forte since my secondary school days. In fact, I used to thumb my nose at the subject. However, water quality is and it has always been my pleasure to share about this topic with all manner of audience and even from a historical perspective.

Click here for the full video of the talk.

Click here for the full write-up of the talk.

 

Public Utilities Board (PUB) drinking water guidelines vs. National Environment Agency (NEA) effluent discharge standards

Hi, thanks for your effort in educating readers about water quality in Singapore.



I was looking at the water quality  table of values published by NEA (http://www.nea.gov.sg/anti-pollution-radiation-protection/water-pollution-control/allowable-limits) and PUB (https://www.pub.gov.sg/Documents/WQ2016.pdf) and noticed that temperature is measured in controlled watercourse such as canals, ponds and rivers but not measured in drinking water. Conversely, turbidity is measured in drinking water but not in controlled watercourse. Is there a reason for this differentiation, please? 



Also, may I have a e-version copy of your book "Your first guide to water quality monitoring in Singapore" please? 



Thanks and regards




Hi,

 

I am not from NEA or PUB so I am not privy to their rationale.

 

However, I can make a guess…

 

Temperature

The drinking water from the water treatment plant (under purview of PUB) exits at more or less ambient temperature. Ditto as it flows the piping network to your home. Therefore, it is pointless to measure temperature for drinking water.

 

In contrast, discharge of wastewater into sewers/water course/controlled water course (under purview of NEA) comes from industry. Depending on the type of industry, the temperature can vary quite a lot from ambient. In the case of sewers, the temperature can affect downstream wastewater treatment operations. In the case of water course/controlled water course, the temperature of the water can affect aquatic life.

 

 

Turbidity

Turbidity is important for drinking water (PUB) as turbid water is obvious to the human eye and no one appreciates drinking turbid water. This includes victims of disasters. Therefore, one of the major parameters to check in water treatment in disaster relief is, you guess it, turbidity!

 

In the water world, turbidity is roughly correlated with total suspended solids (TSS) but unlike turbidity, TSS can an actual amount in mass of the solids in your water. This is probably what NEA prefers when it set up its effluent discharge standards.

 

 

You may sign up in my mailing list to get a free copy of my ebook, Your first guide to water quality monitoring in Singapore.

Good luck!

Figure: Turbidity in water can be obvious to the human eye above a certain level. From left to right: 1, 10, 100, 1000 NTU

Before you rush out to install a filter to improve water quality, think about this...

I just went for eWASH (emergency water, sanitation and hygiene) training conducted by Singapore Red Cross over the weekend. Designed for responding to emergencies and disaster scenarios, it definitely provides a fresh angle on the old topics of water and sanitation. By the way, to me, water and sanitation are simply 2 sides of the same coin (see earlier post on why people learn about wastewater). You can't work on one (usually water) while ignoring the other (usually wastewater) because wastewater typically has a habit of getting back at you through your water if you neglect it.

But hey, when you progress to WASH (water, sanitation and hygiene), you now have a whole lot more factors to consider in addition to getting safe drinking water. (Admittedly, WASH is commonly associated with developing communities but we in developed countries can certainly learn a few things too.)

1. Do you wash your hands before eating and after visiting the toilet?
2. Do you in fact use or have a toilet?
3. Is the way you store your water free from contamination?
4. Is your garbage and other solid waste properly disposed?
5. Is your food safely prepared, handled and served?
6. Do you know that children excreta is just as hazardous as adults'?

Often times in disasters or developmental work (including our students' overseas community service trips), we are too fixated on providing safe, clean drinking water to our beneficiaries. So much so that we forget about the other aspects of health e.g. sanitation, hygiene. In some situations, tackling those less sexy topics can bring about better results to our beneficiaries.

In any case, before we jump in to install a low-tech rainwater harvesting system or a high-tech reverse osmosis water production unit, perform a needs analysis first, whether in a disaster or development scenario. Work on those needs at the top of the list first and not what we "feel" or "want" to do.

My training session provided an interesting study (can't remember the source to cite though) to help bring things into perspective.

Based on various cases, it ranked the effectiveness of the following 4 methods to decrease morbidity rates of diarrhea. Most effective is ranked first... down to the least effective at the bottom. Guess what is at the top and what is at the bottom???

Figure: Do not underestimate the power of the humble washing of our hands

Answer:

1. Hand washing ~30+%
2. Latrine usage ~30+%
3. Sufficient water quantity ~15+%
4. Water quality ~15+%

So you have it... water quality is important but check that you have covered more critical gaps before jumping straight to improve upon it.

Updated by author 23/3/17:
Dr Yoke of WISE (WASH in Southeast Asia) has kindly recommended the following articles on the above topic.

1. Esrey, S.A. et al. Effects of improved water supply and sanitation on ascariasis, diarrhoea, dracunculiasis, hookworm infection, schistosomiasis and trachoma. Bulletin of the World Health Organization, 69 (5): 609-621 (1991)
2. Fewtrell, L. et al. Water, sanitation and hygience interventions to reduce diarrhoea in less developed countries: a systematic review and metal-analysis. Lancet Infect Dis 2005; 5: 42–52

If you read through them, there exists some uncertainty associated with the data and conclusions. Nevertheless, the idea remains the same - a health programme (even a personal one) should not be overly focused on one particular aspect, say water quality. A holistic approach is ideal but in a non-ideal world in which resources are limited, we should still open our minds to other factors, perform a realistic needs analysis and work on the most critical factor and not on the factor we have a preference to.

Why do people want to learn about wastewater treatment?

Wastewater... what's that? Sounds yucky... what an unpalatable topic... Far removed from the drinking water that we are accustomed to... Something best left out of sight and mind... Let someone else handle it... Government, perhaps? Or PUB?

Yes, those will be the typical reactions to wastewater. Then why do people still pay money (albeit with PIC (productivity and innovation credit) grant from the government) to attend a course on wastewater treatment? And no, this is not a WSQ (workforce skills qualifications) course so you don't get the normal WSQ goodies from a typical WSQ course. (Well, neither do you need to fulfil the typical requirements from a WSQ course either.)

A bit of background... I just finished teaching this course over 6 evenings. It gives a broad overview of how wastewater is treatment. Of course, it does not go into design, construction of a wastewater treatment  plant. It is studied from the perspective of a plant operator about several standard unit  operations as follows.

1. Activated sludge
2. Sludge digestion
3. Chlorination
4. Industrial waste
5. Coagulation & flocculation
6. Sedimentation
7. Filtration

Basic enough for anyone but still, why pay money to study it???

It turns out that most of these participants are working (or business owners) in the water and/or wastewater industries. They have extensive in the areas they are servicing e.g. project, pumps, controllers but they don't have a good idea of the overall picture in a water or wastewater treatment plant. No doubt, some of these participants are interested to expand their business into new areas in the industry. However, the others simply want to understand how their services fit into the overall scheme of things. And there is always the odd participant who does not come from the industry at all. He is there to satisfy his curiosity of this seemingly little known and perhaps confusing industry.

Just in case you also feel that wastewater should be kept out of sight and mind, always remember that what goes in (food, water) must come out somehow (solid waste, liquid waste). And nature does not discriminate between clean water and wastewater. Dispose of your wastewater without care and it will end up as your drinking water. This is especially evident after disasters when every relief agency is fighting to provide drinking water to the victims, yet ignoring the fundamental necessity of waste management. Water borne diseases inevitably break out and supposedly clean water sources are contaminated with waste.

Have a good holiday, folks! But don't forget to keep an eye on where your waste goes.

More recognition to grey water recycling!

Grey water (1, 2, 3) recycling has always been a less glamorous cousin to rainwater harvesting. After all, rainwater is clean water for drinking, bathing, cooking... all important processes for our health and well-being, while grey water is wastewater best kept out of sight and mind... as long as someone else is taking care of its disposal.

News update: Water is water is water (no typo here) by whatever name. The only difference lies in the "impurities" in the water, hence giving rise to black water (toilet bowl), grey water (sink, laundry, bath), yellow water (urine only), dark grey water (kitchen sink, diapers laundry). All water is intricately connected in the water cycle - both natural and human. In other words, rainwater or any other "clean" water can come from grey water. Therefore, it pays to conserve (read recycle) and handle your grey water properly.

It is therefore great news when I see that PUB has added a section on the guidelines of grey water recycling in Singapore.

1. Alternate sources of water
http://www.pub.gov.sg/conserve/CommercialOperatorsAndOther/Pages/AlternateSourceofWater.aspx
On this page, rainwater and grey water are officially recognised as alternative sources of water, not just at the national level or at the residential/individual level. I have written about rainwater harvesting in an earlier post.

2. The document itself
http://www.pub.gov.sg/conserve/CommercialOperatorsAndOther/Documents/greywaterRequirements.pdf

Some highlights

1. It goes without saying - no potable use. But irrigation and general washing are also forbidden. Why then do you recycle grey water???
   
   Well.... it can only be used for toilet flushing and as cooling tower make-up water.
   
   Personally, depending on your treatment process, grey water can even be made potable. Even with simple treatment, its water quality can be made adequate for general washing and irrigation.
2. As for rainwater harvesting, grey water recycling must follow PUB's standards for fittings and code of practice for water services, as well as NEA's standards for prevention of mosquito breeding.
3. Raw grey water should not be stored for more than 24 hours. This IS reasonable as any time longer will lead to anaerobic conditions and foul odours.
4. Treated grey water should not be retained for more than 72 hours. This DEPENDS on the type of treatment. If the final water quality is that of drinking water, I am sure the duration can be stretched.
5. Incidentally, there is no mention of WHAT type of treatment process you should use... Instead, whatever treatment must produce a water conforming to the water quality guidelines (listing the various water quality parameter and their limits) given in this document. This is immensely useful as previously, there were no such guidelines.
6. And also very useful is the schedule for water sampling and monitoring e.g. testing for E. coli and coliform should be done monthly.

 Figure: PUB guidelines for treated grey water quality

Figure: PUB sampling regime for treated grey water

Source of the above 2 figures: PUB document (http://www.pub.gov.sg/conserve/CommercialOperatorsAndOther/Documents/greywaterRequirements.pdf)

In conclusion, I believe we are on the right track on publishing such standards for grey water in terms of its water quality and testing schedule. I hope more developers and individuals will take up the challenge to implement grey water recycling on a residential or building scale.

Natually, there is much more to be done. E.g. I am impressed when habitats use plants not only to clean up grey water but also to provide edibles for their inhabitants. Bananas can be clearly seen in my previous posts (1, 2) illustrating this concept in an Earthship.


Figure: Bananas, anyone? (Source: http://blog.insureandgo.com/food-and-drink/2013/03/8-amazing-facts-you-might-not-know-about-bananas/)

My current green project part 1: grey water recycling system

Here is the mindmap which I presented to a group of participants for a major green project we are working on. (Sorry, can't reveal much detail at this point of time.) It contains the important design considerations for a grey water (i.e. water from the sinks, shower, laundry BUT not the W.C.) recycling system inherent in the project. (Click on the figure on look at the whole map.)

 Figure: Possible candidate for the plant treatment cell - Canna Lily. This is an example of phytoremediation - using plants to clean up the environment.

Figure: Another possible candidate for the plant treatment cell - Heliconia sp. Both candidates are easily available in Singapore as they are extensively used in landscaping.

For more information on phytoremediation, refer to my previous posts here.

Singapore wastewater reuse

Dear Sir,


I am currently looking for information regarding wastewater reusing in Singapore.

Basically, I am looking for the Singaporean regulatory framework as far as reuse of wastewater is concerned, to answer this very specific question : which recycled water quality for which use (agricultural, domestic, urban uses…) ?

I have found your blog very interesting and I wonder if you could help me to find the information I need or to advice me where I could find it.

This would be extremely helpful.

I really thank you for your diligence.

Yours sincerely,
N


Dear N,

As mentioned in an earlier post, Singapore is a small country so almost all its water needs and wastewater (domestic) handling services are provided by a single government agency,  PUB (Public Utilities Board). Again, due to the country's size, reuse of domestic wastewater is limited to the production of NEWater and industrial water by none other than PUB. NEWater is a highly purified water suitable for high-end electronics manufacturing (and drinking of course) but also used to supplement our reservoir water. Industrial water is non-potable and only used by chemical industries in Jurong Island.

The water quality of NEWater is partially given here (I am sure many more other tests on NEWater have been performed though their results are not publicised). Water quality for industrial water is even harder to find. You probably have to approach PUB for more answers.

Good luck.