Wednesday, January 20, 2016

Ok, water from the water treatment plant is clean... do I still need water filters?

Dear CK,

I have read below 2 articles with great interest and I like your logical reasoning very much.

I understand that water level in Singapore is clean and that PUB has exceeded WHO guidelines. However, I have one further question in regards to the need of water filter for home.

The water is clean at PUB treatment plant. But the water will need to pass through the pipes before reaching our home. We do not know when was main pipe in the ground was last changed? For sure, the small pipe leading to our home is as old as the building which we live in.

Please note that I am not affiliated with any water filter companies. I just want to learn more as I am thinking of purchasing a water filter system to clean the water at final stage before boiling and drinking.

I look forward to your advice. Thank you very much.

Best Regards,

Dear KH,

Thank you for enjoying my writing style. I always prefer to keep things simple, straight to the point and free of unnecessary technical jargon, with some humour (dark or otherwise) thrown in if possible. Naturally, some technical terms are unavoidable since water itself is a technical subject.

You are absolutely right. Water straight out of water treatment plants is definitely within specs. The question is what happens in between the outlet of the plant and faucet in your house? We are talking about miles and miles of piping, pumps, valves, tanks.

And if you look at the figure below, we are also talking about third parties like town councils and building management committees  (BMC) sharing in the responsibility of providing you with nice, clean water. (Also, note where the responsibility of one party ends and the other begins.)


Anyway, the same question has been raised before in the media in Jul 2009. Do go through it as some interesting points had been put forth, accompanied by equally interesting answers from PUB, a concerned expatriate, a doctor and others.

  1. In case you did no go through the above articles, I will summarise their contents here. In a nutshell, yes, contaminants can enter your tap water along its tortuous journey. Assuming PUB is doing its job well of maintaining its extensive distribution network (no reason to assume otherwise), it boils down to how well your town council or BMC is doing its job in maintaining its piping and tanks.
  2. Barring unexpected incidents like finding a dead maid in the water tank, by regulation:
    Management corporations and town councils must engage a licensed water service plumber at least once a year to inspect and, where necessary, clean and disinfect their water tanks and certify that the tanks are fit for drinking water storage."
  3. The most common culprit in your tap water is rust (an iron compound by the way) silt. It comes from the corrosion of iron piping, especially older piping. It can be visible in water or seen on your filter elements. PUB maintains that this is harmless.
  4. The recommendation is to run your tap till the water becomes clear. Then you take that water for consumption. (Whatever the case, whether iron or other contaminants, this is my recommendation too! Especially in the morning when water has remained stagnant in your piping for long hours during the night. Stuff, if any, from your pipes tend to leach into your water during this time.)
  5. Finally, though the last portion of the water distribution system is not under PUB's jurisdiction, you can call it up if you suspect anything amiss in your tap water.

Regarding the last point, PUB will typically send a technician down to take a sample of your tap water back for testing. The test result will come back as either the water is in compliance or out of specs. Don't expect to see what water quality tests have been conducted and certainly don't expect to be shown the test data.

Still, if the water is out of specs, I believe PUB will then bring pressure down on your town council or BMC to better on the ball on its maintenance programme. Either way, you are safe. Do you still need a water filter then?

Remember the rusty silt that makes your water look "dirty"? Yeah, it is supposed to be safe. Meaning no one, including your town council, will be doing anything about it. Iron (or rust) can be bothersome because it can impart a metallic (or bloody taste at higher concentration) taste. Another problem of iron/rust is it can stain clothes, walls, floors. What colour of stain? Think of rust - orange, red, brown and any colour in between. 

Notice the orangey stuff inside the pipe - that is the tell tale sign of iron. Yup, it is a form of rust. They usually arise from cast iron or galvanised pipes.

If it bothers you (it BOTHERS me), by all means, get a filter to remove it. Nothing fanciful, a cloth filter can do the job. Or if you want something more reliable and can afford the space, get a 10-inch sediment filter rated for 10 microns or less. The rating tells you the maximum size of a particle that can go through i.e. anything more than 10 microns will not pass through the filter.

Figure: A 10-inch 5-micron pleated filter used for experimentation

So far, I am only talking about iron in water. Piping can impart other less desirable and far less benign pollutants into your drinking water. This is usually true in older piping before people became enlightened about the dangers of various materials in drinking water.

  1. Case in point - lead. Commonly used in old piping networks in solder at the joints. Hong Kong has an interesting case - "Water pipes of thousands of flats in Hong Kong will have to be replaced after initial tests revealed excessive levels of lead in the water of a two-year-old public housing estate in Kowloon." Yup, the year was 2015 and the housing was only 2 years old. The blame was placed on the plumbers (and later the contractors) who used substandard materials containing lead solder (banned in HK) from China.

    As a follow-up to the HK story, attention then turned to
    Singapore as one of the contractors (China State Construction) was also involved in some projects here. Rising to the occasion, PUB categorically replied, "Lead or lead alloy, and water fittings made of lead or lead alloy, including soldering joints with lead content are not allowed for use in potable water supply systems in Singapore"

    Results of lead poisoning are well known. As a neurotoxin, it causes mental retardation. Children are especially vulnerable, leading to learning difficulties and delays in development. Unfortunately, lead can come from the food we eat (e.g. adulterated medicines) and the air we breathe (e.g. lead dust from leaded paint).
  2. Asbestos. This was formerly used in cement piping for reinforcement. Over time, as the cement pipe undergoes wear and tear, the asbestos fibres can end up in the water. Though inhalation of asbestos is the most common route of entry, evidence suggests that cancers in the esophagus, larynx, oral cavity, stomach, colon and kidney may be caused by ingesting asbestos.

    I can't really find any data on the usage of such piping in Singapore. If anyone has any information, please let me know.
  3. Copper. Possibly from copper pipes. The copper corrodes over time into water. Bluish green stains are signs of copper in water. Less of a health concern unless the concentration is high. You can sometimes see the same coloration on the exterior of copper pipes because the copper has reacted with substances in air.

Wednesday, January 06, 2016

Stuff that you should know about UV treatment of drinking water

Happy New Year to you !

I would like to check if you have heard about Tami Water system - Strauss Water.? Searching through your blog, I could find topics on UV treated water.

Would like to hear your professional opinion about UV sterilize water treatment, is it necessary in Singapore ? prolong exposure to UV treated water is it safe?

The BB system you mentioned looks a bit bulky for most kitchen top though I really like stainless steel products. Looking for a convenient and safe water filtration system.

Sorry I don't know how to pose questions via your blog.

Thank You and Best Regards,


Hi R,

Personally, I do not see the need for a water filter for Singapore tap water. The water is already quite clean so any filter will be hard pressed to clean it further. (See this post and others in the filter/purifier tag.) Unless you suspect your pipelines and/or water tank are somehow contaminated. Still, it will be easier to call your residential management to take care of it. Or unless you have a medical condition that requires very clean water to be consistently provided.

A small note on water parlance: "sterilisation" means the destruction of all microbes while "disinfection" means the significant reduction of microbes. Water is normally "disinfected" to make it safe for drinking. It is not practical and necessary to sterilise water for drinking. Sterilisation is usually done in medical applications (e.g. sterilising surgical tools), microbiological setting (e.g. incubation for bacterial count) or pharmaceutical manufacturing.

As for UV (ultraviolet) treatment of water for drinking, you probably have already guessed my opinion that it is similarly not necessary for Singapore tap water.

How does UV work?
UV disinfects by disrupting the DNA in microbes (aka bugs). If the DNA is sufficiently damaged (enough contact time or UV power or both), the microbe cannot repair that damage and its bodily functions will be affected, leading to a halt in reproduction or death.

In case anyone thinks I am against UV, let me proclaim that I am a fan of UV treatment in the situations that it is necessary. Its main advantage is it is a relatively simple system to operate. You just need to plug into a power supply and you are good to go. No messy chemicals to resupply, no need to calculate dosage of chemicals and no chemical waste to fuss over its disposal. UV can work under any temperature and pH. These are two master parameters which will invariably affect any water treatment involving chemical reactions. You do not need to worry over the undesirable generation of disinfection by-products (DBPs) including potentially carcinogenic chloroform in the case of chlorination.

Even though UV treatment has been worded as "UV radiation" or "UV irradiation", there is absolutely no ionising radiation (e.g. X-rays) involved so no way will your water become radioactive. UV is generally safe for water disinfection.

Remember the bugs you killed or injured by UV earlier. Though they can no longer reproduce, their dead and dying cells are still in the water. There is some concern these cells can be pyrogenic (fever causing) or become food for other bacteria further downstream. Nevertheless, unless your dead/dying cell count is very high, I believe this should not be an issue.

Of course, you have to be aware of UV's limitations as well. UV is only for disinfection of bugs in your water. It does not remove metals, pesticides, solvents and other chemical substances. (Admittedly, UV does destroy certain organic compounds but most UV units are not designed for this function. Even those experimental ones designed for this function are usually combined with other methods e.g. ozonation, addition of hydrogen peroxide.)

UV also does not leave any residual in the water after treatment. Let's say chlorination - it leaves chlorine residuals in the water long after leaving the water treatment plant. Enough to last till the water comes out of your tap. In between treatment and your tap, the residuals prevent recontamination by microbes as the water flows through pipes, pumps, valves and whatnot. Not so for UV, your water is on its own after UV treatment unless you intentionally add chemicals e.g. chlorine, chloramines, for that purpose. (Hmmm.... that kind of defeats the purpose of using UV, doesn't it?)

One big challenge of using UV is your inflowing water has to be very clear (turbidity of  less than 1 NTU for the techies out there). If your water contains solids e.g. clay, sediment, the bugs will hide behind these solids and receive shielding from the full power of your UV light.

Yes, you do not have to resupply chemicals in UV treatment BUT you have to replace the UV lamp periodically as it will lose its power over time.

Finally, the lamp may be fouled over usage. Grime, dirt, debris can stick to the lamp and these stuff prevents your UV light from shining out effectively. Cleaning then becomes an important part of maintenance. Industrial UV setups usually have their lamps protected by removable sleeves. Even then, the sleeves themselves can be fouled and thus have to be cleaned as well.

End of UV talk

Tami Water, Strauss Water... No, I haven't heard of them but I made a quick search and took a look at their webpages. They seemed like an aesthetically packaged water filter (carbon blocks + UV) that can provide both hot and cold water. As I said earlier, you don't really need water filters in Singapore. Unless you are interested in their hot/cold water combo function. But looking at the price (S$1200 for the Tami Primo model), I don't think that is the most efficient use of your money.

If you really must get a water filter, Arkwater does provide one in stainless steel housing a Doulton ceramic filter. It is pretty slim and designed for countertop use. (Let me stress that I do not derive any benefits from the sale of their products.)

Figure: My trusty Steripen portable UV water treatment unit. Note the UV lamp on the left end.

Figure: Disinfection in action. Notice the bluish light at the lamp. It is supposedly safe for the eyes as the UV cannot escape from the water surface. It takes 1 minute to disinfect 0.5L of clear water. If your source water is murky, it pays to at least sieve your water through a clean piece of cloth or coffee filter before going to UV.

Saturday, December 26, 2015

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.

Wednesday, April 22, 2015

Some non-water related musing

Hi CK,

I just want to join with those to say a "thank you" to you for creating such an interesting blog!  I don't believe we can find the sorts of info you're writing about anywhere else!

You have also provided a certain level of "consumer" info e.g. on alkaline water etc. that is pretty useful to other laymen.  Once again, thank you - I enjoyed reading the articles you have put up.


Hey, thanks, S.

It is always nice to hear such encouraging words from my readers.

Being an educator myself, it is always uplifting to have current and former students providing positive feedback to reinforce the fact that what we are doing is right. (Don't be mistaken, negative feedback is valuable in helping us improve ourselves but the pure happiness of receiving positive feedback is irreplaceable.) 

Being humans, there are times when we doubt ourselves no matter how strong our convictions are. Are we walking the right path? Is this worth doing? Are we making a difference?

During those trying times, even a short encouragement or a few kind words make all the difference. And sometimes, our whole future can change from the decisions we make based on that short conversation with a kind soul.

I have been on the receiving end, as well as on the giving end. Sometimes, we may not think much of our own kind acts. To us, it may be the most natural thing to do. But to the other party, it can a virtual lifeline, a way out of the darkness into the light.

Therefore, I consciously try my best to spread kindness whenever possible. Small acts, quick words but the impact can be bigger than we think. And in a way, that is the right thing to do.

I may not be able to bring a whole nation out of poverty into the status of a developed country but I can help others along the journey of life, making a part of the world (no matter how small) a better place than I first encounter it.

I write because I like to. Water and its topics just happen to be what I am familiar with and working on. Education is a tool. Above all is the attitude to share your knowledge and willingness to better our own condition and that of others.


Sunday, April 05, 2015

Why I wouldn't be drinking alkaline (aka ionised) water

A bit long of a post but try to read it fully to get a well rounded story.

Alkaline or ionized water was all the rage some years back in the domestic water category. It hasn't lost it shine though. New and supposedly ever better models are still coming out and sales staff are still fervently promoting the benefits of drinking alkaline water.

In fact, in c2011, I was approached by one company to write a book on the health benefits of alkaline water. Being somewhat skeptical then (and even more skeptical now), I respectfully decline.

Then in c2013, another company approached me to conduct experiments to help substantiate the claims of its ionized water. This time, instead of talking about drinking the water itself, the company is interested in promoting the use of ionized water to preserve food, cooking and preparing beverages. It was convinced that food and beverages prepared as such were fresher, better tasting while retaining the benefits of drinking alkaline water. In this case, I must admit that the request was kind of outside my expertise so I happily pass it along to my food colleagues.

(It should come as no surprise that alkaline water can preserve food well because of its high pH which makes the environment hostile to most microbes, especially if the food is dipped in a large vat of alkaline water.)

So how is alkaline water produced anyway?
It is typically produced in a machine commercially named a water ionizer. One part of the resultant water has above neutral pH (alkaline) of 8-11. (FYI, the pH scale ranges from 0 (highly acidic) to 14 (alkaline).) You can actually make alkaline water yourself (DIY) by adding sodium bicarbonate (just a fanciful chemical name for baking soda) into your water. But since the profit margins for selling baking soda are simply too low compared to selling a shiny and sophisticated machine like a water ionizer, no self respecting company will want to mention the possibility of DIY to make alkaline water.

[Start of tech talk]
Back to the water ionizer... it makes use of electrolysis - passing an electrical current through water between 2 electrodes - 1 positively charged, 1 negatively charged. In simple terms, positively charged ions (cations) like calcium and magnesium migrate to the negatively charged electrode (cathode) while negatively charged ions (anions) like sulfate and chloride migrate to the positively charged electrode (anode). The cathodic region becomes alkaline due to reactions between the cations and water and no surprise, the anodic region becomes acidic due to reactions between anions and water.

To further prevent the cations and anions from coming together again, ion selective membranes (a really thin film with special properties) separate the cathodic and anodic regions, allowing ions to pass only in 1 direction. In proper technical speak, the whole process should be called electrodialysis (because of the membrane) rather than electrolysis but I suppose electrolysis sounds easier to digest for most sales people and customers.
[End of tech talk for now]

Lots of water ionisers come with filters and other water treatment accessories e.g. activated carbon. To me, they complicate the issues regarding alkaline water. If you become healthier after drinking alkaline water, is it because of the alkalinity itself or is it because the water is cleaner after filtration? Nevertheless, I will focus on alkaline water per se in this post. You can find out more about water filters in my other posts.

How does alkaline water benefit you?
If you read up on the advertised claims of the suppliers, alkaline water can:
  • delay ageing
  • counteract cancer
  • detoxify
  • lower blood cholesterol, sugar and pressure
  • remove stones
  • prevent arthritis
  • weight loss
  • improve energy levels
  • keep heart, liver, bones healthy
  • probably improve lots of other health issues you can think of
What a list! Don't get me wrong, there are indeed things that can improve many aspects of your health. Think of exercise for example. Exercise can do all of the above and more. It makes me wonder why some people are not doing it. Maybe they prefer to buy a quick fix like a water ionizer. After all, drinking ionized water does not come with the hassles of spending time and effort exercising and getting all sweaty and uncomfortable.

Naturally, I am skeptical when a commercial product or service comes with more beneficial claims than snake oil. After all, how do you effectively prove so many claims. It is not easy to do scientifically robust studies to prove a single health claim. You need time to do that. For example, drugs can take years or more before they are allowed to be sold on the market. The gold standard will be clinical studies of patients involving double blind experiments. You don't see that with alkaline water (and lots of other health supplements). Yes, I know drugs are different from alkaline water but the health claims are no less serious and in many cases, alkaline water sounds more omnipotent than any drug.

And in some cases, the suppliers use BIG words like "miracle" water. This really sets off the BIG warning alarms in my head and have me recoiling with BIG question marks.

Eventually, what you often see are "testimonials" from "satisfied" customers. "After drinking alkaline water form XYZ brand, I feel healthier... I no longer suffer from health problem ABC... At first, I am unsure but after trying it out, I am a true believer." I bet you see roughly the same testimonials as above more often than you care to count. In a way, they are selling hope but what you don't want is when hope and reality don't meet.

By now, I can hear some of you asking what does WHO say about pH in its drinking water guidelines. Well, in WHO 2011 edition, there is no recommendation for pH as it is not a health concern though Singapore's Environmental Public Health (EPH) regulations stipulate a pH of 6.5-9.5. I believe this range is more for protection of piping and equipment against corrosion in too acidic or alkaline an environment.

The Science behind the scenes
Sometimes, scientific theories are presented out of context. Yes, acid and alkali neutralise each other. So if you body is too acidic (bad for health), simply drink some alkaline water to achieve balance again. Simple, right?

If you believe that, maybe you also believe that you can remove your brain from you body and hook it up with wires and electrodes in a nutrient vat so that you can live beyond the demise of your body. (Just kidding) Unfortunately, our bodies are really complex machines. What works in a vat usually does not work in the real body with its many biochemical/biomechanical operations interacting in ways many times as yet not understood.

Figure: An interesting and ultimately unanswerable question: "How do you know you are not a brain in a vat somewhere and your whole reality simply fed into your brain via electrochemical/biochemical signals?"

Take pH for example. Human blood pH is an average of 7.4 (slightly above the neutral of 7). Drop below 7.35, you get acidosis. Go above 7.45, you get alkalosis. Both conditions can lead to serious health complications. The reason why human (and animal) blood needs to maintain such a stable pH is because pH is often quoted as the master parameter in any system, be it human body or a pond. It affects how chemical and biochemical reactions will play out. A different environmental pH will lead to a different reaction pathway, giving rise to different products. Or the reaction may not even proceed at all.

So why are people talking about the body being too acidic? The body will automatically correct the blood pH within the narrow range of 7.35-7.45. (WE are talking about blood pH here. Saliva and urine will have a slightly different pH range. Stomach pH IS acidic - see below. Healthy fetal blood pH is also slightly different.) How in the world is alkaline water helpful?

For those who remember your biology, stomach pH is acidic, say 1.5-3.5. You need this level of acidity to properly digest your food and to kill off many pathogens. (IN chemical terms, the acid is to break up the chemical structures of foodstuff like proteins so that your digestion enzymes can do their work on the fragments.)

IN case you are worried that drinking alkaline water will neutralize this acidity, good news - a healthy stomach can automatically compensate for such actions and retain it normal pH range. So my point is - when you drink alkaline water, it ends up mostly in your stomach where it is neutralized by your stomach acids. How are its benefits supposed to be transferred to your body??? (FYI, once your acidic stomach contents reach the small intestine, bicarbonate is secreted to neutralize the acids so that the acidity does not travel further down your system.)

Lastly, if anyone reading this feels strongly about alkaline water being really vital for health, please do not flame me and just go ahead to drink it if it makes you feel better. This is after all a free society. As for me, I will keep alkaline water at a distance. More often than not, we just need an adequate dose of good old plain water to function efficiently at optimum health. Keep this a priority before you open your wallet to other "healthy" options.

Figure: If you find yourself feeling lethargic, sometimes all you need is to hydrate yourself. Above is my favourite type of water bottle - stainless steel. Tough, no chemicals to leach and possible to use it for boiling the water if necessary.

Sunday, March 29, 2015

Enough clean water for my children and their children - remembering Mr Lee Kuan Yew (LKY)

This week (23 - 29 Mar 2015) marks the mourning of the passing of our first prime minister, Mr Lee Kuan Yew (LKY), widely recognised as Singapore's founding father.

As I was going through the historical documentaries of the man shown continuously on TV, I was reminded of his contributions to the water supply in Singapore. The early years of Singapore (1960s, 70s) were trying times. Massive issues had to be resolved right there and then - housing, education, healthcare, security, jobs and of course water and sanitation. It was mind boggling to contemplate these issues all together, much less come up with workable solutions.

Anyone familiar with human nature should realise that once the basic human needs (e.g. food, water, shelter) are not met or disrupted, you are going to have lots of trouble on your hands. Think about looting, rioting and general social unrest - just look at Chile, Haiti after earthquakes. I am sure there are many more such examples if you google them up.

No, in the chaotic situation that is Singapore in the 1960s, water needs must be effectively addressed. (Sanitation too as I believe water and sanitation are merely 2 sides of the same coin hence the term, watsan but sanitation is a story for another day.)
'In 1963, just a few years after its self-governance was declared, Singapore experienced a severe drought. This harsh experience left a deep mark on the population. As the Prime Minister of Singapore at that time, Mr Lee Kuan Yew was determined to drive Singapore towards water sustainability. This, he did by making water a top priority in government policies. "This [water] dominated every other policy. Every other policy had to bend at the knees for water survival."'

In those early days, LKY already realised that there would not be enough water given the paces of development and population increase. Water from reservoirs and from Malaysia were not going to make it. (Only MacRitchie, Pierce, Seletar and Fort Canning (for the port) were operational as of 1963. Source: PUB) (As of the 1960s, the very first agreement signed in 1927 was no longer in force. 2 others - 1 signed in 1961, another one in 1962, were then operational. Source: Singapore Infopedia)

Looking at the scene now (2015), I am quite pleased to see the 4 National Taps operating - local catchment, imported water, Newater, desalted water. By 2060,
  • Total local catchment area will have increased from the current 2/3 to 90% of surface area (see previous post related to this topic)
    "Currently, NEWater meets up to 30% of the nation’s current water needs. By 2060, we plan to triple the current NEWater capacity so that NEWater can meet up to 55% of our future water demand."
    "Today, desalinated water can meet up to 25% of Singapore’s current water demand. The plan is to grow Singapore’s desalination capacity, so that the Fourth National Tap will be able to meet up to 25% of our future water demand by 2060."
  • What is so special about 2060?
    "Beyond 2061The Singapore government has stated that it will not renew the 1961 agreement which expires in 2011. Attempts to reach a new deal with Malaysia to secure water supply for Singapore beyond 2061 have not borne fruit despite years of tedious negotiations. To reduce Singapore's dependence on imported water, the government has taken steps to increase the size of the local water catchment area and to build up the supply from non-conventional sources, namely NEWater (reclaimed water) and desalinated water. With the various water projects progressing well, government officials have assured Singaporeans that the country can be self-reliant in water by 2061 if it needs to be."

    Yup, so that is it. The last 20% will be served by local catchment by 2060.
With such forward planning, I feel assured that the water needs of the country and my family will be well met...

But... (there's always a but) all these come at a price. Newater and desalted water are not cheap to produce. Requiring sophisticated reverse osmosis units using easily fouled membranes, they basically involve passing contaminated water through a filter that removes the contaminants. Imagine a filter with really small holes that only allow water molecules to go through. Even small stuff like salts and oils are retained on the filter. This is going to use lots of pressure to push the water through and  associated with it are high energy usage and costs.
"The first year (2003) tender price for NEWater from Singapore's Ulu Pandan plant was S$0.30/m3, which is significantly less than the cost of desalinated water. The selling price of NEWater is S$1.15/m3, which covers production, transmission and distribution costs."

"The cost of the desalinated water during its first year (2005) of operation was S$0.78/cubic metres."

Desalted water is naturally more expensive to produce than Newater because seawater is much more saltier ("contaminated") than normal wastewater in our sewers. As such, you need much higher pressure (translated into energy and cost) to filter off the salt in seawater.

In contrast, the production cost of tap water should be in cents/m3 (sorry, can't find a good source for this figure. I picked it up when I studied about reverse osmosis in university.)  

Finally, don't forget that to ensure water security for our small nation, energy security is a co-requisite. Without natural gas, biofuel or whatever to generate electricity, desalination and Newater production will be adversely affected.

Thursday, March 26, 2015

The curse on the waters off Pasir Ris

The waters off Pasir Ris seem destined to be cursed with massive fish kills now and then. Fish kills have been documented there for years! (See my previous posts on this topic.) The latest came as no surprise - Straits Times 1, 2; Today 3, 4; Channel News Asia (CNA) 5.

In response to an invitation from CNA to check out the waters there, a team of us headed down to the field for a quick water quality monitoring (WQM). It had been a week since the fish kill occurred so I was not expecting to see anything extraordinary in our WQM results. Nevertheless, it was a good chance to stretch those hands and legs on some good old field work.

Other than conducting field trips for my students as part of their curriculum, it has been some time since I have field work in WQM. For those following my blog, I had been involved in other aspects of water the past few years - rainwater harvesting, grey water recycling. Water is such a fascinating yet vast topic. It can cover indoors, outdoors, natural, industrial, agricultural, household, economics, political, war and many other areas besides.

Back to Pasir Ris... On 10 Mar 2015, we did WQ tests at 2 spots at Pasir Ris and 1 spot at Punggol for reference. Here is a summary of the results.

The number above may appear intimidating but worry not, below is a description in plain English.

Overall, the water quality looked pretty good for all 3 locations. A few points:

1.       The water at Pasir Ris has become somewhat saltier compared to my data in 2010.

2.       The water has also become somewhat more alkaline compared to my data in 2010.

3.       The water is significantly clearer (less turbid) compared to 2010. Less construction work going on?

4.       Nutrients (ammonia, nitrate, phosphate) are significantly less compared to 2010.

5.       Bacterial counts are significantly less compared to 2010. Can we all swim there now?

6.       Pasir Ris spot 1 appeared to have a slightly higher bacterial count compared to the other 2 locations. FYI, spot 1 is where a great deal of dead fish were washed up the previous week.

 Don't forget, about a week has passed since the fish kill. Don't expect to see problems in the water quality during our field trip or we will still be seeing dead fish on the shores for the entire week - a scary thought.

Figure: WQM team at work at Pasir Ris

Figure: The cozy CNA van that brought us and our equipment around our test sites