Tuesday, May 31, 2016

The must-have resource for the rainwater harvester

If anyone out there feels like setting up their personal rainwater harvesting (RWH) system, this is a must-have book.

Rainwater Collection of the Mechanically Challenged by Suzy Banks and Richard Heinichen

I came across this when I was working on my RWH project and found it immense useful, especially for the DIY homeowner.

Written for the layperson (that included me when I first started out on RWH), it is simple to read. It doesn't bore you down with details. Instead, it gets straight to the point of setting up your RWH system, supplemented with simple diagrams that anyone can follow and implement.

Though designed for the DIY homeowner, it is also useful to help you know what you are getting into even if you intend to let a contactor handle the installation.

I especially like the section on sizing your rainwater storage tank. (Yes, you do need a storage tank for RWH and this will take up the most space.) It is clear and the mathematics simple. I can hardly find similar information elsewhere.

There is a section on troubleshooting which will come in handy when (not if) you encounter operational problems.

Of course, its strength and limitation is the assumption that you are living on landed property. Its ideas are based on the private home setup. For example, the setup is based on using the roof as the collection receptacle and gutters to pipe the rainwater for storage. If you are installing RWH elsewhere e.g. industrial/commercial buildings, this book does not offer alternatives so you have to read up more and customise accordingly.

Essentially, their setup is made up of:
(The order below follows the flow of rain on the roof all the way to the tap.)
  1. Roof
  2. Gutters
  3. First flush diverter
  4. Storage tank
  5. Pump (+ electrical components)
  6. Pressure tank (+ electrical components)
  7. Filters
* The above are linked with piping, fittings and valves. The authors are proponents of PVC piping so no other alternatives are discussed.

The book discusses concisely and clearly how to set up the above components to make them work as an efficient whole. I find their descriptions adequate for you to go down to the bolts and nuts on  your own but yet not excessive that you are overwhelmed by indecision leading to inaction.

Besides the landed property assumption mentioned above, do note that the setting in the book is based on Texas in USA. If you are from another state or country, obviously, you have to double check your local laws on RWH which may or may not coincide with what the authors suggest.

For those in Singapore, it is mandatory to read the following:
  1. PUB Guidance notes for the application of rainwater collection systems
  2. NEA guidelines on mosquito prevention in domestic rainwater collection system for non-potable uses

A couple of highlights from the above 2 documents
  1. The application to PUB for a RWH system has to be lodged by a qualified person (PE or architect). Unless you are a QP yourself, be prepared to engage one (with a budget for his fees) to apply on your behalf.
  2. If you are going to use gutters, your application will be routed to NEA for its approval too. And they have certain guidelines for your gutter design to comply with.
Good luck!


Saturday, May 28, 2016

Demystifying NSF/ANSI standards for water filters (part 2)

Hi folks,

This is an addendum to my earlier post, Demystifying NSF/ANSI standards for water filters (part 1)

NSF/ANSI certification
I mentioned about checking for NSF/ANSI certification on your product. One way is to look for the NSF mark on your product, packaging and/or documentation. It may look like this:

Figure from NSF
Figure from NSF
  1. Do note that that the words on the mark may differ. Besides the above 2 examples, you may see "certified for home use" and other phrases being used.
  2. The actual standard is not necessarily shown on the mark e.g. NSF/ANSI 42, NSF/ANSI 53. You will have to check the packaging or dig through the documentation for that.
  3. The letters "NSF", white circle and blue leaf background seem quite standard but expect to see variations e.g. the following personal product is compliant to NSF/ANSI Standard 305 
    Figure from NSF
 NSF Certified vs. “Tested to NSF Standards”
 One more thing - be careful of products that claim to be "tested to NSF standards". It is meaningless as it is not really certified under NSF, hence there is no guarantee at all regarding its performance. see NSF for more details.

NSF certification has to be renewed yearly by the way.

Apparently, no anyone can perform the testing for certification. The ONLY three certifying organisations are NSF International, WQA (Water Quality Association) and UL (Underwriters Laboratories). 

Stay safe.

Wednesday, May 25, 2016

Demystifying NSF/ANSI standards for water filters (part 1)

In a couple of previous posts, Do we really need water filters 2, Evaluating the necessity and usefulness of water filters for domestic tap water and Why the Sawyer mini filter is my current favourite portable water filter, I touched on the NSF/ANSI (National Sanitary Foundation International/ American National Standards Institute) standards, specifically standard 42 and 53. I thought that more information about these standards should be addressed and at the same time provide an update on other relevant and newer standards.

Do you know that NSF/ANSI standards actually cover many diverse activities seemingly related only by their effects on health? They range from food equipment to vending machines, dietary supplements and residential dishwashers, making up to about 50 standards. But for the sake of the topic in this blog, I shall just present the following ones relevant to water filtration/purification.

Technically, all the following have the prefix "NSF/ANSI standard"
  1. 42: drinking water treatment units - aesthetic effects
  2. 44: residential cation exchange water softeners
  3. 53: drinking water treatment units - health effects
  4. 55: ultraviolet (UV) microbiological water treatment systems
  5. 58: reverse osmosis (RO) drinking water treatment systems
  6. 60: drinking water treatment chemicals - health effects
  7. 61: drinking water system components - health effects
  8. 62: drinking water distillation systems
  9. 177: shower filtration systems - aesthetic effects
  10. 401: Treatment Systems for Emerging Contaminants
  • Standards 44 and 177 are rarely applied in this part of the world (Singapore) since we hardly use water softeners and shower filtration. But they see significant usage in places like USA. (Updated by author: I am referring to residential usage. In commercial, industrial and academic setting, water softening is of course used. E.g. to get consistently good tasting coffee in Starbucks, you need to soften the water to a consistently low level of calcium and magnesium.)
  • Standard 401 is newly developed in reaction to the public's concern over pharmaceuticals in drinking water.  This standard covers up to 15 contaminants including drugs, herbicides, pesticides, chemicals used as flame retardants and detergents.
  • Of the greatest interest to most consumers will be the ones I have made bold - standards 42 and 53.

If the above list looks formidable (actually only 10 out of the 50 standards), don't worry. I am not going through all of them.

In a next post, I will use NSF/ANSI 42 as an example to illustrate how the standards can be applied to your water filtration situation. Once you get the hang of these standards, you can go ahead to find out about the rest yourself or you can wait for my future posts. (Besides 42, I recommend looking at 53 at least plus 58 if you have/want a RO system or 62 if you have/want a distillation system.) But for a start, let's go through some basics.


Read this first... some background information
  1. If you try to search for the document online, good luck! It is apparently not available in digital format (yet), even on the official NSF website - www.nsf.org
  2. Hardcopies are hard to come by too. You probably have to order 1 from NSF itself. Luckily for me, my campus library has a few standards on hardcopy.
  3. If you do manage to find a hardcopy of the standard, reading through is not exactly a walk in the park. You have to wade through legal talk and technical jargon. And in the end, you may still not find what you want.

All right, do I really need NSF/ANSI certification?

Probably the most important question.

But since I am not you, I don't know about your situation - water quality, budget, constraints etc. So I will answer this from my perspective.
  1. NSF/ANSI happens to be a prevalent certification, if any, for water treatment units in the market. Therefore, YES! I prefer to get a water filter certified under NSF/ANSI (especially standards 42 and 53) but please note that a standard itself is not as straightforward as you think. There are some finer details you HAVE TO CONSIDER.
  2. However, note that these standards have so far been used to certify residential units. Certified portable units are still few and far between but there seems to be trend in this direction too.
  3. There are of course other certifications and endorsements out there e.g.
    1. US EPA (Environmental Protection Agency)
      caters more for removal of microbes by portable units in the outdoors
    2. Red Cross, Red Crescent, Unicef
      Some filter suppliers will quote that various Red Cross, Red Crescent chapters, Unicef etc. have approved the use of their filters in various humanitarian relief situations
    3. Some countries e.g. Japan have their own certification schemes
    4. The above are all fine, I suppose but do ponder on whether the above situations apply to you. Are you living in a refugee camp with an inadequate and unreliable supply of water?
If you decide you want NSF/ANSI certification for your filter, check that
  1. It is clearly stated on your filter's packaging and documentation that is certified as such.
  2. Double check that your particular brand/model really does come with the certification. This is the easy part, simply go to:
    1. http://info.nsf.org/Certified/DWTU/
      This can search for filters according to manufacturer, brand, model, standard, claim and others
    2. For example, if you want to check for NSF/ANSI 42 certification, simply choose the standard from the drop-down list, and click "Search". You should find your desired filter inside the results, it really is what it claims it is.

As mentioned earlier, being certified under a standard by itself is not enough, you have to look deeper to check if you are really getting what you want. I will cover this in a next post...

Monday, May 16, 2016

Why the Sawyer mini filter is my current favourite portable water filter

Readers who have read my posts would know that I am not a fan of residential drinking water filters for where I am staying now - Singapore. However, water filters can be necessary when:
  1. You are going to or currently staying in a less developed area of the world where
    1. there is no piped water
    2. Or the piped water is of questionable quality
  2. You want to prepare for emergency scenarios in which you are not expecting piped water to come out of the tap anymore.
  3. You want to engage in disaster relief i.e. an emergency scenario has already occurred somewhere else and you are heading there as a responder.
Under point number 1, I believe in carrying along a portable water filter whenever I am heading out into the wild, even somewhere as near as the jungles of neighbouring Malaysia. But through the years, I have also brought my water filter along even if I expect to be staying in hotel rooms. I guess that is the boy scout in me telling myself to be prepared. (Hey, it's true - I was a scout in my school days!)

For the past 10 years, this was my favourite portable water filter - the Katadyn Mini. It uses a ceramic core to remove bacteria and parasites and it is good for 7000 litres! Wow, that was a good deal of capacity in those days. Plus it small (relatively) size, few filters came close.
Figure: Katadyn Mini
Then technology happens...

It progresses so rapidly that sometimes we lose track of better products coming out in the market. I started hearing about the Sawyer Mini water filter for a year or two but didn't think much about it. After hearing a fair share of its good reviews, I decided to give it a try. Here's a comparison between the my old and new favourites.

Figure: top - Katadyn Mini, middle - Sawyer Mini

First thing you notice is the significantly smaller size of the Sawyer. At this size, it can be really handy to carry around. In fact, you are more likely to forget that it is there in your bag.

And if you read its specs, they look impressive. It has a capacity of 100 000 gallons (yes, that translates to roughly 380 000 litres!). If you are in survival mode and need only 2 litres of drinking water per day, this mini beastie will work for 500 years - virtually forever!

It is designed to filter down to 0.1 micron absolute. (In contrast, the Katadyn is rated down to 0.2 micron. Since they did not specify on the package that the rating is absolute, I believe it should be nominal.)  It is cited to remove 99.99999% of bacteria and 99.9999% protozoa.

The size and specs are no doubt wonderful but in my opinion, its unique selling point is its versatility in usage. You can use the water pouch (included) to store your raw water. Connect up your filter, squeeze and you get drinking water straight into your mouth.

Figure: https://sawyer.com/products/sawyer-mini-filter/
And if for some reason, you lose the pouch, no worries, simply use the ubiquitous PET soda bottle to store your raw water. Attach the filter on top and you are good to go.
Figure: https://sawyer.com/products/sawyer-mini-filter/
 And if you ever are desperate enough to be without the water pouch or a soda bottle, you can attach the straw provided and drink straight from the water body.
Figure: https://sawyer.com/products/sawyer-mini-filter/
As an aside, the first water filter that allows the drinker to drink straight from the pond is, I believe, the LifeStraw. Widely publicised and distributed to developing countries, it was indeed a technological marvel. It was rated for 1000 L, 0.2 micron nominal, 99.9999% removal of bacteria and 99.9% removal of protozoan cysts. Incidentally, both and LifeStraw and the Sawyer filter make use of hollow fiber membranes, in contrast to a ceramic element in the Katadyn Mini.
Figure: Comparing the LifeStraw (above) and the Sawyer (below). Notice that the LifeStraw is only designed to be drank straight from the water source while the inlet and outlet nozzles of the Sawyer make it infinitely more versatile.
Best of all, it can be used as an inline filter, either sourcing from your own personal hydration pack or connected to a communal water tank.
Figure: https://sawyer.com/products/sawyer-mini-filter/

Filters for Life Program – Worldwide
Figure: http://watercharity.com/tags/filters-life

But before I go overboard on the Sawyer's strengths, do note that it is not rated to remove viruses. It also does not remove taste, odour and colour. (Therefore, it is possible for your filtered water to appear yellowish if your raw water is coloured to start with.) It has no activated carbon to remove these unsavoury stuff. And it definitely does not remove pesticides, heavy metals. Do not even try with seawater.

Though I mentioned its advantage as an inline filter, do not try fixing it to your water mains. The hollow fibres are rated to a maximum pressure of 60psi but the casing will actually burst at 40psi as a safeguard. Your mains may or may not exceed that pressure.

Finally, it is not certified under NSF/ANSI standard 42 or 53 which of course are designed more for residential water filters. Still, some water filter bottles are starting to get such certification.


Yes, the above image and several links in the text are Amazon Associate links. But I have to stress that no way will I recommend products that I myself do not believe in. More often than not, I have used them personally and am confident of their performance.

Monday, February 22, 2016

More advice on water filtration: Berkey vs. Doulton, material for water storage

Hi Chen Ko

Thank you so very much! Your reply made my day. I truly appreciate you taking the time to advise ( and I can see you are a truly a teacher at heart, sense of humour included!). Know this has been a very busy period for most, myself as well.
I hope you will be able to clarify on two parts relating to Qns 4 & 5:

Qn 4: "Therefore, if you are getting a Berkey filter, do check whether they are using the new filter elements or the original Doulton/BB filter elements."

Meaning to say, between the original Doulton/BB (British Berkefeld) filter elements and the new Berkey (Black Berkey) elements, which is superior in terms of filtration? I note the inverted commas you used when you talked about NMC "improving" the original filters... 😉 so I want to know if the Black Berkey might really be a level up!

Qn 5:

The Pure Effects website pointed out that for gravity-fed filters, a main disadvantage is that " the water sits in contact with the holding chamber (plastic or metal) and has ample opportunity to absorb metal/plastic ions before going into your cup. Bacteria & fouling are also a concern with standing water in such systems (especially in warmer weather), as well as constant exposure to air/touch."
What are your views on these points raised? The potential bacterial growth does sound like something to be concerned about, and I am not sure what can be done to combat it properly and sufficiently.

I would be most grateful if you could help clarify further on these. Thank you very much and I hope you have a wonderful weekend too.



Hi Paloma,

Thank you for your kind words. Here are my thoughts to your queries.

Q4: Doulton/BB vs. Berkey

Very observant of you to notice the "" in the word "improving" :-)

I am assuming that you really do need (or want) a water filter and whatever capabilities they have to offer. Let's further narrow down to only 2 choices - Doulton vs. Berkey filter elements in a gravity fed setup.

Here is an interesting read on Berkey's website comparing the 2 filter elements. Naturally, it concluded that Berkey is superior to Doulton.

I will leave cost out of the picture because the prices of the 2 seem close and depending on who you purchase from and what promotions they are offering at the time, 1 or the other can come out cheaper.

"While the Doulton is capable of removing 99.99% bacteria and cysts, it is not capable of removing viruses to the required 99.9999% that qualifies the Berkey as a water purifier. The Big Berkey is capable of 99.9999% removal of bacteria, 99.9999% removal of cysts, and 99.9999% removal of viruses"

The same capabilities of Doulton were given in Arkwater's webpage. However, on the Water for Life webpage, it mentions 99.9999% (i.e. 6 log reduction) removal of bacteria but only 99.99% (i.e. 4 log reduction) removal of viruses. No mention was made of removing cysts.

Heavy Metals
Berkey's webpage claims that their standard filter elements can remove heavy metals and Doulton ones will need a post filter. However, if you get a Doulton ATC SuperSterasyl, you can too remove heavy metals without a post filter.

"The Big Berkey produces a maximum of 84 gallons per day with the standard 2 element system compared to a maximum of 12-15 gallons a day produced by the standard Doulton system."

My biggest issue lies with this claim. Basically, they are saying that the Berkey can filter 5-6 times faster than a Doulton. Both filter elements are about the same size and made up of various media compacted into a very tight matrix with tiny pores allowing water to pass through. If you want to remove more contaminants e.g. microbes, you need the pores to be smaller and/or more surface area for the water to pass through. This translates to a longer travelling time for your water within the filter element. Yet, for some reason (perhaps some undisclosed scientific innovation/ breakthrough), you can still get an output of 5-6 times over a similar competitor. But I assume such a scientific innovation/ breakthrough (if indeed it is one) will not be cheap.

Without sounding cliche, remember a customer always wants a product/service to be cheap, good and fast. He can only get good and fast but not cheap or any other combination of 2 desirables but never all 3.

IF you are concerned about viruses in your water, yes, do get the Berkey, though I imagine the Doulton should be able to remove viruses to a certain extent.

Otherwise, I believe it ultimately comes down to cost. Although the Berkey webpage lists several advantages in terms of warranty, I am not sure whether they apply to international customers. Good luck choosing!

Q5: Leaching of chemicals and fouling

Seriously, short of processing your water through force fields without contacting any material, all filters/purifiers have issues of potential chemical leaching and fouling. In a gravity filter, it is more obvious because the filtered water is stored in a container, waiting to be used.

In the case of Pure Effect Filters (countertop, under-counter or whatever), does the water not have to pass through filter housings (usually plastic but can be stainless steel in other brands/models) holding the filter elements? When you close the faucet, whatever water remaining in the setup will still have to sit inside these housings. Depending on the materials of construction and the environment, these housings too have the potential to leach chemicals into your water or become covered by a slime layer of bacteria/algae on the inside over time.

Pure Effect Ultra Filtration System
Figure: I count 3 housings in this countertop filter from Pure Effect Filters and they are apparently made of plastic.

The trick is to have a knowledge of how safe various materials are. Plastics have been having a bad reputation the past years because of the high profile and nasty chemical, BPA found in certain plastics. BPA basically helps to hardens a plastic but evidently, it can leach into water it comes into contact with, especially at elevated temperatures. It has been linked to a range of human health problems, including a higher risk of certain cancers, reduced fertility, birth defects and diabetes. To make matters worse, the so called BPA-free plastics are not guilt free either. Studies have shown that the BPA substitute, BPS can display similar or worse effects compared to BPA.

As underlined earlier, not all plastics are created equal. Some are clearly more hazardous than others. HDPE, LDPE and PP have been cited to be the safest plastics. Not sure which plastic is which? Check out the recycling codes (a number within a triangle) usually on the underside of a container. Codes 2, 4 and 5 indicate HDPE, LDPE and PP, respectively.

But my personal favourite material for water storage is STAINLESS STEEL (SS). Strong and durable, the container itself can even be used to boil the water inside. It also is less conducive to bacterial growth compared to plastics. Plastics can be easily scratched and these minute depressions are ideal for microbes to stick on, unlike a smooth surface on SS. This also happens to be the material that most Berkey and Doulton filters use for their containers. (Some Berkey and Doulton filters do come in  plastic containers. I personally prefer the SS version of course.)

No doubt, glass and ceramic are generally very safe but due to their breakability, they are not my favourites.

A few final points
Whatever material you use, maintenance is still needed. You can't be lazy and leave the container as it is. Open it up to check. If you find deposits and slime growing, for goodness sake, please clean it with soap and water at least. SS is clearly superior as it has less chance of getting scratched and small pieces dislodged during cleaning. And it is resistant to most cleaning chemicals (NOT bleach though).

However, SS can be corroded in a salty environment. Drinkers of salty soup and sauces beware... and not just from the sodium you are ingesting. You may be ingesting chromium and other elements which are part of SS.

Friday, February 19, 2016

Advice on water filtration in Singapore: alumina, boiling, gravity fed vs. counter-top

Hi Chen Ko

Firstly, thanks so much for your informative blog. I am on the market for a new drinking water filter system to replace my Hyflux Gurgle, and have been trying to do my homework before buying anything. 

So far, the Berkey system seems to be a frontrunner since it is available in Singapore, and seems to do the job well (btw, one of my main requirements is fluoride removal. I agree with you about alkaline water and I am not keen on that). 

However, being a layperson, it can be hard to separate the wheat from the chaff. Hence, I am writing in hoping you may be able to spare some time to shed more light on the following areas:

  1. I note from your blog that you did feel that Singapore water does not need to be filtered. I saw Singapore's Drinking Water Quality report and while I believe by international standards it is indeed excellent, as a layperson I was surprised by all that is in it! What might you say would be the top 3 or 5 substances in Singapore that consumers should try to filter out, if possible? Filters out there claim to filter out radiation, pharmaceuticals, etc, but I am not sure what might be the biggest contaminants here be. "Relevant" and appropriate filtering is a concern to me as I enjoy drinking a lot of water daily.
  2. I read that activated alumina (which I believe Berkey uses) is not aluminium, and is therefore safe. Is this really the case though? Some filters use calcium-based carbon (bone char) instead. Are alumina-free filters such as that to be preferred, then, for the sake of health and safety?
  3. I read too that while boiling water kills microorganisms, it actually concentrates contaminants as well! Does that mean it is a bad idea to boil water (either filtered or unfiltered) before drinking? (Well, too bad though for coffee/tea. ;-) )
  4. If I remember correctly, you use British Berkefeld aka Doulton? I read that you said these are the same as Berkey. Could you pls enlighten me if their efficacy is the same? I went to the Arkwater website but their products and terminology are not exactly the same as the Berkey, so I had difficulty assessing which is better.
  5. The website of the Pure Effects water filter system pointed out some convincing disadvantages of gravity-fed filters like the Berkey, and I find it hard to assess if these are deal-breakers e.g. chloramine removal, bacterial growth - could you pls advise? (Pls refer to the comparisons made in this chart and this table.) Personally, I find the Pure Effects filter a bit more complicated, but am willing to consider it if it is better than Berkey.
Thank you so much for reading my e-mail and I do apologise for e-mailing you directly. I would be most grateful if you are able to share your thoughts with me as well as your blog readers. 

Wishing you a good week ahead! 



Dear Paloma,

Sorry for the late reply as I was occupied with end-of-semester issues and the recent Chinese New Year.

In reply to your queries:

  1. As you have already mentioned, the tap water quality in Singapore is already excellent by WHO standards (see PUB's drinking water quality report). Frankly, I don't see how the top 3-5 contaminants to be filtered out can be chosen in a rational manner. Unless you expect something else has entered your water in between the water treatment plant and your tap. See previous post for more about this scenario.
    We are now treading into the territory of long term (decades perhaps) health effects and controversial research findings. You can also add in the popularity of certain contaminants for research and media reporting and viola, the weightage of any particular contaminant of concern can be skewed in either direction.

    Furthermore, potential filter/purifier owners please note... As mentioned several times before in my posts, the already low concentrations of contaminants in our tap water make them rather difficult to remove any further. Removal may only be marginal or worse, a poorly maintained water filter can actually add contaminants (e.g. bacteria) into your drinking water.

    My only concern for our tap water:

    Fluoridation. I am not sure why we are still doing it here.
    Our tap water is intentionally fluoridated (addition of fluoride) to fight against tooth decay. However, studies have shown that fluoride can be bad for health (arthritis, mutagenicity etc.) and unlike decades ago, we are already getting enough fluoride from our food and toothpaste. Of course, its level in our tap water is very low and certainly within WHO standards. I just don't see the logic of adding it in the first place.
  2. Activated alumina is basically aluminium oxide made very porous. This allows an incredibly large surface area to remove fluoride, arsenic, selenium as water passes through the pores.

    Compared to the element, aluminium, alumina is much more stable chemically so aluminium is not likely to come out of alumina. Yup, that is the wonder of chemistry - an addition (sometimes in very small amounts) of something else can change the original material radically and make it more practical. A common example is iron and steel. Iron by itself is weak and impractical but add in some carbon and now you have steel which is ubiquitous in our daily lives.

    Figure: Activated alumina (https://en.wikipedia.org/wiki/Activated_alumina)
    In answer to your question, alumina is pretty safe to use. Generally... UNLESS you pour acid on to it. Then alumina does break down and goes into your water. You don't happen to run acid through your water filters, do you? Before you run out to check the pH of your tap water, relax... it is slightly alkaline.
  3. Boiling does reduce the volume of your water somewhat but most automatic kettles will switch off quite fast once boiling is reached so the reduction is small, say 5% or less. Don't forget, your contaminant in tap water is already at a very low level. Assuming it does not boil off as well, its concentration will simply increase by about 5%. No such a big deal and no way it is going to break any limits in the drinking water standards.
  4. I dug a bit more into the Doulton/British Berkefeld (BB)/Berkey story. Apparently, a guy called Doulton started producing ceramic filters in England in early 1800s. These filters came to be known as Doulton filters. These were subsequently modified to incorporate silver particles (for their anti-microbial properties) and registered under the trade name of "British Berkefeld". In 1998, a company called New Millenium Concepts distributed the Doulton/BB line of filters in America under the name of Berkey. At that point in time, Doulton/BB and Berkey carried the same products. However, NMC started "improving" on the original filters and came up with "Black Berkey" filter elements which are claimed to filter off more contaminants and more efficiently on certain existing contaminants.

    Therefore, if you are getting a Berkey filter, do check whether they are using the new filter elements or the original Doulton/BB filter elements.
  5. Let me reiterate I maintain my stand that water filters/purifiers are not necessary for Singapore tap water in general. The reasons why I suggested the Doulton/BB filter in my previous posts were for emergency preparedness in the Singapore scene and  residence in less developed countries e.g. community service where clean water is not a guarantee. Keeping these reasons in mind, I would expect electricity to be absent or unreliable so a gravity fed filter is a really good idea.

    But it seems you still want a filter for Singapore tap water. I am sure you have your reasons and I will respect your decision. Since you mentioned coffee/tea of which I am also a fan :-), you are not getting a filter to make better coffee/tea, are you? Oh, for those of you frequenting coffee joints like Starbucks, it is normal for them to run tap water through several filters before brewing their coffee. This is supposed to produce consistently better tasting coffee compared to the unfiltered brew most of us "enjoy" at home.

    Ok, back to our topic... for pressurised water such as from a tap, I prefer to get a countertop model like the one presented at Pure Effect (I have no wish to endorse their products so there is no link here even though it is available in Paloma's email above). Or you can go for an under-sink model if you find space on your counter very limited. (I am sure those who own the newer HDB flats in Singapore will agree.)

    These flow-through filter systems address the main weaknesses of a gravity fed one - you have to manually pour water into a gravity filter once you have used up the limited amount stored below the filter elements (say 18 litres depending on model you get). Since it is by gravity, the filtration is going to be slooooooooooow. In contrast, a flow-through system supplies filtered water on demand - no waiting time, no hassle of topping up the filter tank and no concern about the storage capacity of the tank.

    Furthermore, Certain flow-through models can use the exact same filter elements (e.g. Doulton) as the gravity fed version - same filtration effectiveness but with greater efficiency since you do not have to wait for gravity.

    Figure: Doulton countertop model utilising Doulton (of course!) filter elements inside. http://www.arkwater.com/residential.html

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.)

Source: http://wildsingaporenews.blogspot.sg/2009/07/brown-tap-water-still-safe-for-drinking.html#.Vp8I6RHVxjo

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. 

Source: https://sprinklerwarehouse.files.wordpress.com/2012/08/rusty-pipe-small.jpg
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.