Wednesday, October 19, 2016

Water Quality Workshop Quick Survey

I am planning a new workshop on water quality for professionals intending to further their understanding in the growing water industry or educators wanting to learn about the intricacies of water education.


Having gotten feedback from a few associates, I would like to further refine the scope of my workshop before rolling it out. As such, if you can spare 5-10min to complete a survey here, I would much appreciate your contribution.


In addition, I will share a summary of the survey results with all respondents. (Incidentally, this is something I would like to see more surveyors practising when I participate in their surveys.) The survey will close on 31 Oct 2016.


Start the survey now.


Thank you

Wednesday, October 05, 2016

Should you be worried about lead and asbestos in your drinking water?

This is a follow-up from my earlier post - Ok, water from the water treatment plant is clean... do I still need water filters?

It has a couple of open ended remarks which I feel should be addressed. In addition, I have been queried about these same points by my students.

Nasty substance to consume. Well known for its neutrotoxicity, it causes mental retardation. Children are especially vulnerable, leading to learning difficulties and delays in development. Being a systemic poison, it can also lead to high blood pressure and kidney damage. Unlike many other elements, lead has no useful purpose in the human body.

Is it in our water or not?
Bear in mind that I am speaking about Singapore tap water here. Apparently, this issue has been brought up before to PUB, especially after the lead in water scare in Hong Kong in 2014. (Jul 2016) (Jul 2015)

In a nutshell, the articles tell us not to be worried about lead in tap water here because
  1. Our local regulations state that “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,”
  2. Extensive monitoring and sampling are done on water in various stages of its treatment and conveyance, all the way to the tap end in the consumer's premises. No lead has been detected so far.
  3. Older pipes (which MAY have lead) are continually and systematically being replaced with the current safe ones.
My thoughts
  1. Unless you happen to live in a really old building which still retains its leaded pipes over the decades... and unless somehow your building falls under the radar of the extensive sampling and monitoring programme... then maybe you should be worried.
  2. Nevertheless, I still prefer to see more transparency on the sampling and monitoring programme e.g. where and when do sampling and monitoring take place. How often are they done? Better still, more water quality data should be available to the public. A once-a-year report that averages the values for the 100+ water quality parameters seems too superficial.
Image result for Lead in pipes
Figure: lead and copper pipes

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.

First, it seems that WHO is not convinced that ingesting asbestos in drinking water poses any hazard to health. Hence, there is no WHO guideline value for asbestos in drinking water.


And in case you are still worried, good news here!


In 2008, there was a major exercise by PUB to replace 120km of Asbestos-Cement Lined pipes to Ductile Iron pipes with cement lining. It seems the only pipes we have under PUB jurisdiction are either ductile iron with cement lining, stainless steel or copper.

Since asbestos cement (AC) pipes are typically only used by PUB for its major pipes, even your old building should not have them.

Image result for asbestos cement pipe
Figure: AC pipes

Hope the above are helpful to you in assessing your risks and assuaging your fears. Good luck!

Wednesday, July 20, 2016

Certification of bottled water?

In a previous post, I replied to a reader on bottled water. I thought I should write a bit more about this topic of bottled water here.

Bottled water is probably worse than drinking water in terms of the bewildering plethora of regulations and certifications. To streamline this discussion a bit (and also to keep this post readably short), I will just touch on some of the major ones.

International Bottled Water Association (IBWA) (based in USA)
Bottled water companies can pay to become its members. It has a documented code of practice here. However, members have the discretion to follow (or not to follow) the code.

The document includes guidelines for operating a bottling plant, water quality parameters to test for in both source and finished water.

It also has definitions for the different types of bottled water. Other regulatory organisations have roughly similar definitions. If you thought bottled water is simply water, check out the following xxx water.

  1. "Artesian Water" or “Artesian Well Water” means bottled water from a well tapping a
    confined aquifer in which the water level stands at some height above the top of the aquifer.
  2. "Demineralized Water" means bottled water which is produced by distillation, deionization,reverse osmosis, or other suitable process and that meets the definition of purified water.
  3. "Deionized Water" means water that has been produced by a process of deionization and that meets the definition of "purified water"
  4. "Distilled Water" means water which has been produced by a process of distillation and
    meets the definition of "purified water"
  5. "Mineral Water" means water containing not less than 250 parts per million (ppm) total dissolved solids (TDS), coming from a source tapped at one or more boreholes or springs,
    originating from a geologically and physically protected underground water source.
  6. "Natural Water" means bottled spring water, mineral water, artesian water, artesian wellwater, or well water which is derived from an underground formation or water from surface
    water that only requires minimal processing
  7. "Spring Water" means water derived from an underground formation from which water flows naturally to the surface of the earth.
USA Food and Drug Administration (FDA)
In USA, bottled water is tightly regulated by FDA. Note that tap water in USA is regulated by EPA instead.
Some interesting points:
  1. "FDA monitors and inspects bottled water products and processing plants under its general food safety program, not a specific bottled water program.
  2. As with other types of food, FDA periodically collects and analyzes samples of bottled water.
  3. FDA laboratories may test the water for microbiological, radiological or chemical contamination. Individual samples are not tested for all possible contaminants cited in the quality standard, but for selected contaminants, depending on the reason for the sampling.
  4. Bottled water is considered to have an indefinite safety shelf life if it is produced in accordance with CGMP and quality standard regulations and is stored in an unopened, properly sealed container. Therefore, FDA does not require an expiration date for bottled water. However, long-term storage of bottled water may result in aesthetic defects, such as off-odor and taste. Bottlers may voluntarily put expiration dates on their labels.
  5. The materials used to produce plastic containers for bottled water are regulated by the FDA as food contact substances. Food contact substances must be approved under FDA's food additive regulations."
EU's European Federation of Bottled Waters (EFBW)
All bottled waters are strictly regulated under EU law.

Of particular interest is Directive 98/83/EC on the quality of water intended for human consumption. Like other regulatory documents, it lists down quality standards (these as usual include chemical, microbiological and radiological parameters), sampling and monitoring.


National Sanitation Foundation (NSF) (based in USA)

As seen above, FDA and EFBW are legislative and regulatory in nature while IBWA is more about self-regulation/compliance. Guess what, NSF is really about certification!

Its certification process seems quite comprehensive
  • HACCP (hazard analysis and critical control point) and ingredient review
  • Facility audit
  • Product testing
    • The client get to choose which regulations to test against e.g. FDA, EU, WHO
  • Source water testing
  • Label review
  • Recertification
    • Done yearly via an unannounced audit and product testing
Bottled water supplies certified as such will get to stick the NSF logo on their products and have their company names listed in the NSF database.
In case you are thinking to rushing to click the above database link to see whether your favourite bottled water is listed there and if you are staying in Singapore (SG), I think you may be disappointed. Hardly any of our local bottled water suppliers are shown. In fact, the only NSF certified bottled water I found (though there may be others I am not aware of) is Icelandic Glacial Natural Spring Water retailed by Watsons. (No, of course I am not promoting or endorsing the drink. I am simply using it as an example.)

Personally, I believe NSF certification is a great step forward for a bottled water. IT definitely endows more confidence to the consumer on the safety of the product.
Finally, what about SG itself?

When I did a quick scan of the bottled water around me, it seems most of them come from Malaysia and Indonesia unless you have the cash to spare and buy brands imported from Europe. Quite a few large companies have bottled water labelled with their companies' logos and names and those are typically from our 2 neighbouring countries.

Before you suspect the safety and quality of these uncertified products, understand that all bottled water in SG are regulated under AVA.

Referring to AVA's document, many documents have to be submitted to AVA e.g. site plan of the water source, factory licence, authentication certificate for import of bottled water. Every consignment has to be accompanied by a health certificate that includes the concentrations of various water quality parameters (microbiological and chemical, no radiological though).

In addition, "meeting the import requirements does not exempt the imported consignments from inspection and sampling for laboratory tests by AVA"

My take
Unlike water filters, bottled water (even more for tap water) is pretty regulated in terms of legislation. Still, compare AVA's bottled water requirements of about 30 water quality parameters to WHO's ~200 parameters for drinking water or PUB's similarly numerous parameters for tap water and you get the idea that bottled water is lagging behind in its stringency... unless a bottled water supplier is willing to get NSF certification based on WHO drinking water standards.

So buyers take note, bottled water is not necessarily safer than tap water.

Saturday, July 16, 2016

Bottled water vs. tap water

Dear Mr Chen Ko,


I read some of your blogs and would appreciate your advice. As I understand a minute amount of NEwater is added into the reservoirs and then subsequently makes its way into our tap water through the normal processes. 


While the amount of NEwater is small, I am now thinking of using bottled water for my family. I have been searching through and I can't find any company that provides distilled water made from mineral water. They all seem to state that their distilled water is from the local water supply.


If one was to buy mineral water, would that be good for the body in the long run? Or do you have any suggestions on other types of water to consume, such as spring water and etc.


Your earliest reply is appreciated.



Dear Shabbir,

  1. For those outside of Singapore (SG), Newater is our national brand of water further reclaimed from the effluent of wastewater treatment plant (euphemistically named water reclamation plant (WRP)). Our local and only water utility company, PUB, has been adding Newater in small amounts into our reservoirs. The combined water is subsequently sent for water treatment before ending up in our taps.

    Just wondering, do you have any particular concerns with regards to this practice? I am neither pro- nor anti-PUB but I fail to see any problems arising due to this. Water is water and with the proper treatment, any contaminant can be removed or at least reduced to below detection limits.

    Figure: Newater

  2. A couple of thoughts about bottled water
    1. It is expensive! Easily the most expensive form of water vs. tap and filtered water. If I have the money to go long term on bottled water, I will probably use an alternative source of water and use the leftover money for something else :-)
    2. The plastic itself lends to waste. Though recyclable, I would rather not use it in the first place.
    3. Certain bottled are treated (filtered or otherwise) tap water. In the case of bottled distilled water, the treatment includes a distillation step.
    4. Depending on how clean the treatment and bottling setup is, bottled water can already be contaminated with fecal matter, bacteria, solvents etc. despite its beautiful packaging.
    5. Even so called "mineral water" are often produced by adding chemicals (aka minerals) into treated water. Only in certain cases are the water really obtained from real mineral water from the ground.

      Figure: bottled water

  3. As for distilled water
    1. It is similar to RO (reverse osmosis) water, demineralised water (possibly by ion exchange) and Newater in the sense that it has little constituents i.e. as close to pure water as you can get.
    2. Therefore, it does not make sense to produce distilled water from mineral water. All the minerals would have been stripped, rendering the perceived advantages of mineral water moot.
    3. Water, whether distilled, demineralised or RO, is "aggressive". It has so little constituents that it becomes reactive.
      1. There had been claims that it can leach minerals and nutrients from your body. However, there are studies that have refuted otherwise so I personally think that this issue is inconclusive.
      2. Of greater concern is such aggressive waters can attack (read corrode) the distribution network, leaching chemicals from piping and fixtures. How would you like to have your coffee laced with lead and copper?
      3. And don't forget how you store your water. If your storage container is not inert like glass, the same aggressive water can also leach out chemicals from your favourite plastic jug.
      4. Others claim that these "pure" waters are doing a disservice to your body since they are not providing the minerals your body needs. My take is I drink water because I need water. The minerals I need are more effectively obtained from my food or possibly supplements. (Again some studies have shown that minerals e.g. calcium, magnesium can indeed be obtained from your drinking water which I believe. But why bank on your water for a small amount of these nutrients when you should focus on getting a balanced diet?)
  4. In answer to your question: No, I don't believe mineral water (in the form of bottled water) is a long term solution to your water needs because of the reasons given above. In an emergency or short term usage (e.g. 2-week community service in a developing country), bottled water has its place but no more than that.

    I still maintain my stand that our (SG) tap water is good enough to consume unless you have specific concerns, perhaps due to certain health condition or maybe your particular belief in the properties of our tap water. In that case, I recommend that you pinpoint that concern and address it via a suitable treatment method which can be superior to whatever treatment used in bottled water.

Wednesday, July 13, 2016

HiflowAM water: Better type of water? Or just a new kid on the block?

Hi Chen Ko

My apologies for not managing to acknowledge your reply previously. Thank you so much again for the useful info and I hope you had a great June vacation!

I came across a water filter product at a fair recently, I think it is electrolysed water. Was told it is not (the ‘overrated’?) alkaline water per se, but not I am very sure. Was curious to hear your thoughts on something like this, as well as the touted health benefits (better blood flow…?). (see “Comparing various waters” and “Benefits of HiFlo Water” tabs)



Hi Paloma,

When I flicked to the webpage on "comparing various waters", there is this interesting table comparing tap water, RO (reverse osmosis) water, alkaline water, hydrogen water and HifloAM water (which is the product the company is trying to promote).

So now, in addition to alkaline water, we have hydrogen water and HifloAM water to choose from. The consumer must be spoilt for choice. (You may refer to an earlier post about alkaline water.)

The first thing that strikes me is the TM (trademark) superscript next to Hifloam water. RO water, alkaline water and hydrogen water do not have this! What this means is Hifloam water is probably surrounded by secrecy and little is known about it. And when I tried goggling for it, indeed, the first couple pages of results are mainly linked to Nature's Glory, the supplier for you-guess-it.

Even Nature's Glory website itself does not seem to explain the process behind the production of Hifloam water. It does however make many health claims and show a video on improving blood after drinking its product.

I can't seem to find any scientific publications on the website or on Google about the benefits of drinking Hifloam water. This should not be a surprise since the product is trademarked. This should be enough to restrict its independent research. At least for alkaline and hydrogen water, you can still find such publications.

Oh.... back to the table mentioned above. It compares pH (a indication of acidity and alkalinity), ORP (oxidation reduction potential), dissolved oxygen (DO) level, dissolved hydrogen (DH) level and pKw among the 5 types of water. It is trying to say that:
  1. pH should be kept around neutral (i.e. 7), effectively debunking the goodness of alkaline water. (My post on alkaline water touches on this.)
  2. The more negative ORP is, the better it is. In chemistry, it is indeed true that a more negative ORP will tend to promote anti-oxidant activity.
  3. A super high (technically known as supersaturated) level of DO is good for you. DO in Singapore's tap water is about 6ppm but Hifloam water has a off-the-chart value of 14.40ppm. I have seen this kind of value in water with lots of sea grasses photosynthesising.

    Yes, we humans need oxygen but we get ours from the atmosphere via breathing which is a more effective way of obtaining oxygen compared to fishes getting theirs from DO. After all, the atmosphere contains 21% oxygen. This translates to 210 000ppm in the air. Why we need to obtain oxygen from drinking supersaturated DO water is beyond me.
  4. Not sure about the role of DH in drinking water. But having a gas distributed through the human body and playing a beneficial role is not something I easily subscribe to unless I see a lot more scientific evidence.
  5. In chemistry terms, pKw is the negative logarithm of the product between hydrogen ion (NOT hydrogen) concentration and hydroxyl ion concentration. Theoretically, I am not sure how this relates to improving one's health from drinking water with a slightly lower pKw.

Before someone flames me for my comments, I am not such a snob to insist that something beneficial has to be understood mechanistically. Yet, in the absence of more and better evidence, I will tread with caution. I think we have seen enough of quick-get-rich schemes to be more careful in parting with our money.

Figure: Plain water is still best for me.

Saturday, July 09, 2016

Revisiting sustainability: Earthship living

Some years ago, I have written about the organisation, Earthship Biotecture here and here. I still maintain my stand that it is a useful model for sustainable living. As their "Earthships" (what they call their sustainable houses) are based mostly in USA, I have my doubts whether their designs are effective here in tropical Singapore. Nevertheless, they can provide a good starting point for further modification if anyone here wants to have their own sustainable house.

Figure from Earthship Biotecture: Exterior of an Earthship. This is 1 of several different designs.
Figure from Earthship Biotecture: Interior of an Earthship showing a "botanical cell" (the plants area) for grey water treatment

In fact, the Earthship was an inspiration for our very own sustainable living lab in SP (Singapore Polytechnic). I was involved in the designs for the rainwater harvesting (RWH) and grey water recycling (GWR) modules. These culminated in a functional prototype set up in SP - mentioned in some of my earlier posts (1, 2).

Essentially, our lab was planned as a fully functional and sustainable living space equivalent to a 4-room flat. Besides showcasing certain environmental technologies, it was to serve as a practical classroom for our students. But due to reasons which I will not disclose here, the project was terminated. Despite our disappointment, it was a good learning experience for all those involved in its planning and design.

For those out there who want to try their hands to build their very own living lab, I suggest starting with the following books from Earthship Biotechture. (They have apparently come up with more books but these were the two that started me on exploring the world of sustainable living.)

Earthship: How to Build Your Own, Vol. 1

Water From The Sky
For a review that I have written on Water from the Sky, check out here. 

Imagine building a house with old tyres, empty glass bottles, soda cans and ramped earth. Fix up the roof with solar panels and a rainwater harvesting design. Clean up your grey water (i.e. water from the sink, shower, laundry) with plants. Not forgetting you can munch into the fruits e.g. bananas borne by the afore mentioned plants. The "clean" grey water can now be sent to flush your toilet. Water for drinking, cooking and bathing are from the rain. Yup, that about describes what an Earthship is about.

Admittedly, sustainable living is more than living in a green house (NOT greenhouse) or even an Earthship. It includes a whole slew of lifestyle choices that can be inconvenient, uncomfortable or costly. You may have to forgo that dazzling 56" LCD TV or that therapeutic soak in a bathtub (sorry, you have to use the shower like everyone else). Recycled cards are not exactly cheap. Heck, it is far simpler to get your water from the utilities company than having to store rainwater and attending to the maintenance of your RWH system. At least, you worry less about mozzies when your water comes piped in.

Nevertheless, a house designed for sustainability is a good first step to green living. And if it is truly well thought out, the issues of inconvenience, discomfort and cost can be mitigated.

Wednesday, July 06, 2016

How do I test my own tap water: a DIY guide (part 2)

Hi folks,

Please refer to my previous post for an introduction to this topic of DIY testing of tap water by consumer.

First off, let me be the first to admit that I do not test my own tap water. The tap water testing I do is always part of our curriculum, whether as project work or practical training for our students. And occasionally, consultancy work.

However, if you have reason to suspect something is amiss in your tap water, do not be afraid to try testing yourself. Where you take your results from there depends on what you find. You may consider sending some samples to an accredited lab for a more accurate and precise analysis. (For folks in Singapore, I suggest looking for a SAC (Singapore Accreditation Council) - SINGLAS accredited lab through their website. But do look through another of my previous posts on Testing your drinking water - the whys and why nots if you decide to go this route. It also contains the names of labs that I have ever had contact with.

Regardless, here are what I recommend for the independent thinking DIY consumer.

1. E. coli

Industrial Test Systems 487197 WaterWorks EZ Cult Bacteria Test. USD9.77

Each package makes for only 1 test. What I like is it can test for both coliforms and E. coli. (You will need an additional UV light source for E. coli though.) Though not as idiot-proof as a test strip, it should still be manageable for a layperson.

Take note: you need to have an environment of a reasonably steady temperature for the incubation phase - 22-28oC for 48h OR 32-38oC for 24h. You also have to scrupulously clean your hands and contact surfaces to avoid contaminating the kit to produce a false positive result. Being a test kit, the result will not tell the concentration of E. coli in your water. It does tell you whether they are present OR not which is good enough since the guideline value is less than 1cfu (colony forming unit)/100mL water.

2. pH

ColorpHast 9590-3 Test Strips, 0-14 pH (Box of 100). USD19.70
My favourite pH test strips. We actually use these in our labs too. It provides testing in the full pH range of 0-14. Very idiot-proof - just dip one strip in a water sample and take out to match against the colour chart for your pH. This should be a standard item for every water tester.
3. Lead

PurTest DIY Lead Water Testing Kit. USD16.95
A little pricey for 1 single test but simple enough to use. As it is based on an immunoassay, it does not involve chemical reactions and heating. Like many test kits, its result shows lead content above or below 15ug/L. (The WHO guideline value is actually 10ug/L. In this case, the test kit is based on U.S. EPA standard.)

4. Copper
Hach 2745125 Copper Test Strips, 0-3 mg/L. USD23.39
Idiot-proof test strip style of use. This is something we have used before and we find it quick and easy. It's colour graduations allow you to differentiate among 0, 0.2, 0.5, 1 and 3mg/L.
5. Electrical conductivity (EC)
Check out my previous post for a discussion among 3 closely related parameters - EC, total dissolved solids and salinity. My personal preference is to measure EC because it is the fundamental parameter that the other 2 are usually derived from.

Unfortunately, there is no test strip for EC. The following is identical to the one I have been using for years except it is sold under a different brand. It is waterproof and floats on water if you accidentally drop it. Of course, the batteries have to changed periodically. And I changed sensor (the lower portion which goes into the water) once. Easy to measure. The only peeve is you have to calibrate it once in a while to get an accurate reading. And that involves getting a couple bottles of calibration solutions.

Oakton ECTestr 11 dual-range, pin-style pocket conductivity tester. USD79.42 
Please note that the above instrument is only suitable for drinking or fresh water. Do not try using it in brackish or seawater in case some of you are tempted to test it in  your seawater aquarium.

6. Hydrogen sulphide

Industrial Test Systems WaterWorks 481197-20 Hydrogen Sulfide Test Strip, Low Range, 1 Minute and 20 Second Test Time, 0-2ppm Range (Pack of 30). USD16.45
Yup, one more test strip kind of measurement. You will need to a good eye to differentiate the colours sometimes. But I suppose most test strips have this disadvantage.

7. Iron

Hach 2745325 Iron Test Strips (Total Dissolved Iron), 0-5 mg/L. USD23.39
A bit more complicated than a test strip as you have to add in a reaction powder (shown as foil satchels above). Still, should not be a problem for anyone who can follow instructions. Also something we have used comfortably in the past. Note that the lowest concentration of iron measured is 0.15mg/L since this is a test kit rather than a laboratory instrument costing tens of thousands.

8. Manganese

Industrial Test Systems 481020 SenSafe Manganese Test. USD27.29
Another dip and read test strip. Colour graduations allow differentiation among 0.02, 0.05, 0.1, 0.2, 0.5, 1.0, 2.0mg/L.<0 .02="" 0.05="" 0.1="" 0.2="" 0.5="" 1.0="" 2.0="" mg="" p="">
I personally have not used items 1, 3, 6 and 8 but they look promising based on their descriptions and reviews. Item 6 has a mixed review but there is apparently little choice in test strips for hydrogen sulphide.

I also realise that not all the items can be directly shipped out of USA. Therefore, if you really need it and can't find it from another source, you may consider getting a freight forwarder to send it to your country from USA. If you are staying in Singapore like I do, my current favourite forwarder is Ezbuy based on its service and pricing.
<0 .02="" 0.05="" 0.1="" 0.2="" 0.5="" 1.0="" 2.0="" mg="" p="">

Saturday, July 02, 2016

How do I test my own tap water: a DIY guide (part 1)

I had received queries about testing one's tap water without going through the hassle of sending water samples to a lab i.e. the DIY route.

If at all possible, get a water quality report from your water utility company first. This will save you a lot of trouble and perhaps even eliminate the need for DIY water testing.

I believe it is a requirement of water utilities in the United States to provide one to the consumer. However, here in Singapore, we do not have such a luxury. If you express concern about the safety of your tap water, the one and only water utility (PUB) here will respond and send a staff down to your place to collect samples. When your report comes in, it will state safe or unsafe. (I suppose if it is unsafe, they will do further tests and probably act to rectify the problem.) Nowhere in your "report" will  you see the water quality parameters measured and what their values are.

And you want to take matters into your own hands, testing your water DIY is possible. However, the average consumer will be lost and not know where to start. Hopefully, this post will clarify your doubts and give you the confidence to go ahead.

Here, I assume that you are getting your drinking water from the tap. If your water source is a well, surface water body (e.g. pond, river) or others, you may want to check out my previous posts pertaining to a rural setting.

In another post, I actually provided several vendors in Singapore supplying water quality testing equipment. I did not touch on what parameters to check though. also, these vendors tend to deal with businesses and organisations, rather than the average Joe end user.

This previous post suggested the use water testing strips which is still my stand for the average consumer venturing into the world of water quality testing. I will continue with this idea in this discussion. But please be aware of their limitations as given in my post.

What am I suppose to measure?
Without reinventing the wheel, I have taken a leaf out the U.S. EPA (Environment Protection Agency) for the following table.

Conditions or Nearby Activities:Test for:
Recurring gastro-intestinal illnessColiform bacteria
Household plumbing contains leadpH, lead, copper
Radon in indoor air or region is radon richRadon
Corrosion of pipes, plumbingCorrosion, pH, lead
Nearby areas of intensive agricultureNitrate, pesticides, coliform bacteria
Coal or other mining operations nearbyMetals, pH, corrosion
Gas drilling operations nearbyChloride, sodium, barium, strontium
Dump, junkyard, landfill, factory, gas station or dry-cleaning operation nearbyVolatile organic compounds, total dissolved solids, pH, sulfate, chloride, metals
Odor of gasoline or fuel oil, and near gas station or buried fuel tanksVolatile organic compounds
Objectionable taste or smellHydrogen sulfide, corrosion, metals
Stained plumbing fixtures, laundryIron, copper, manganese
Salty taste and seawater, or a heavily salted roadway nearbyChloride, total dissolved solids, sodium
Scaly residues, soaps don’t latherHardness
Rapid wear of water treatment equipmentpH, corrosion
Water softener needed to treat hardnessManganese, iron
Water appears cloudy, frothy or coloredColor, detergents

Looks lengthy? I have narrowed the list by highlighting those conditions which I believe are more likely in an urban setting.

Here's my list of parameters to test for in tap water

No. Parameter EPH regulations My take
1 E. coli < 1 cfu/100mL An important microbiological indicator. Its presence indicates a high probability of contamination from human fecal matter
2 pH 6.5-9.5 Though pH is not a chemical substance, its deviation from the regulated range indicates a  problematic water that deserves further investigation. Anyway, it is so simple to measure, nobody should forgo its testing.
3 Lead 10ug/L Commonly leached from lead piping and fittings in older installations. It causes serious bodily harm so I consider it a priority for testing.
4 Copper 2mg/L Commonly leached from copper piping and fittings. Though less toxic than lead (notice the value in mg/L instead of ug/L), it can cause complications in people with compromised health.
5 Electrical conductivity (EC) - No value given by EPH or WHO. I suggest using the range in PUB water as a guideline: 92-527 uS/cm

Like pH, EC is not a chemical substance. However its deviation from the normal range should warrant further investigation.
6 Hydrogen sulfide - Not measured in PUB's standard water quality report. And I suggest this be measured only you observe foul smells from the water. A concentration above 0.5mg/L should be enough to produce observable smell.
7 Iron - No value given by EPH or WHO as iron is typically not toxic in normal concentrations. However, it can cause staining on clothing and materials. If you have such an occurrence, you may want to measure it. I suggest using the range in PUB water as a guideline: <0 .003-0.013mg="" font="">
8Manganese0.4mg/LUpdate by author: (For some reason, this row as missed out in copying over.) Manganese is typically not toxic in normal concentrations. However, it can cause staining on clothing and materials. If you have such an occurrence, you may want to measure it. 
  • * Environmental Public Health (EPH) (Quality of Piped Drinking Water) Regulations 2008 are based on WHO guidelines for drinking water quality.
  • For some reason, PUB tends to change its web addresses a bit. The latest report with the EPH values can be found here.

  • I would say that parameters 1, 2, 3, 4 are the basic ones you should measure. If you have a bit more money to spare, EC (parameter 5) should be part of your routine too.
  • Hydrogen sulphide is only necessary if you smell foul odours.
  • Iron and manganese should be measured if you find stain on clothing or other materials.

I will make my recommendation for DIY testing in a subsequent post. Look out for it!

Tuesday, June 28, 2016

Demystifying NSF/ANSI standards for water filters (part 3): standard 42

Continuing from my earlier 2 posts (1, 2) on NSF/ANSI standard 42, here's the meat in describing this commonly encountered standard for "drinking water treatment unit" (read water filters).

If you are the lucky few who have a copy of the document, it certainly makes for good bedtime reading i.e. getting you to sleep. Therefore, I will try to be short and sweet in this post.

Even though the title of this standard states "aesthetic effects", it actually covers quite a lot of details in a water filter, and not just how well the filter works in improving the aesthetics of drinking water.

The standard apparently can apply to a "system" (e.g. entire filter unit) or a "component" (a single part of a filter unit). I assume my readers are more interested in evaluating an entire system so I shall focus my discussion on a "system". (This decision is also a conservative measure since the requirements for a component are less stringent than for a system.) Buyers beware: make sure the standard covers the whole filter system you are buying, and not just certain components inside.

To be certified, a filter system must satisfy the five following conditions.
  1. System materials in contact with drinking water must not leach chemicals into the water within specific limits. Chemicals to be tested include aluminium, mercury, vinyl chloride, xylenes and many others. Much is described about how testing is done and the chemicals of concern.

    In other words, you don't want to buy a filter that adds poisons into your drinking water. With such a filter, you don't need poor filtration effectiveness to harm yourself.
  2. Structural integrityThis part talks about pressure testing the materials, design and fabrication quality of the complete system. Basically, your system should not fail (burst, leak) under specific conditions.
  3. Minimum performance requirementsThis slightly misleading title actually refers to mundane matters not covered in the other 4 criteria e.g.
    1. Minimum service flow rates to be achieved under different configurations
    2. Electrical safety and operation complying with National Electrical Code or equivalent.
    3. Filter media (e.g. activated carbon) should not migrate visibly (read leak out of the filter).
    4. A few other requirements
  4. Reduction ClaimsThis is most often mentioned aspect of standard 42, whether by filter suppliers or customers - how the filter reduces the concentration of a certain substance in water.

    Buyers beware! This requirement is potentially the one most likely to confuse a consumer on the effectiveness of a filter. To be certified, a filter has to fulfil a reduction claim of ONLY ONE substance. Make sure you know which substance that is. ABC filter certified to reduce the concentration of only chloramines will have unknown effectiveness against chlorine.

    Again, please remember that standard 42 is designed to certify a filter for improving aesthetic effects e.g. taste, odour, colour. It is not designed for the removal of adverse health effects e.g. heavy metals, pesticides. You have to look to standard 53 for that.
    Substances of concern under standard 42 include:
    Bacteriostatic (NOT killing bacteria but keeping bacteria levels more or less the same before and after filtration),
    Chloramine reduction,
    Chlorine reduction,
    Hydrogen sulphide reduction,
    Phenol reduction,
    Particulate reduction (there are 6 classes denoting different particulate size ranges so do check out which class is being certified),
    a few more other parameters e.g. iron, zinc, manganese

    Again, we see the usual descriptions of testing methods and influent challenge (i.e. the characteristics of the inflow into the filter)

    Here is an example of the reduction requirement for chloramine:
    Average influent (aka inflow) challenge concentration: 3.0 mg/L +/- 10%
    Reduction requirement: 0.5 mg/L
    (meaning the outflow should have a concentration of 0.5mg/L or less)
  5. Instruction and installation
    1. Details must be provided for installation, operation and maintenance
    2. Some other details
    3. And easily as important as the reduction claims, a performance data sheet must be available to potential buyers

      Buyers' tip! Scrutinise the performance data sheet. (Some filters not certified under this standard may have it too.) It may look discouragingly technical but it should look similar to the following example. (Influent challenge refers to the test sample going into the filter while product water refers to the outflow from the filter.)

      Obviously, if the filtered is certified, its performance should equate or exceed that of the standard.
Sample Performance data sheet reduction claims
Substance influent challenge concentration maximum permissible product water concentration
Chloramine 3.0mg/L ± 10% 0.5mg/L
Iron 3-5mg/L 0.3mg/L
foaming agent 5mg/L ± 10% 0.5mg/L

Believe me, I have really tried to simplify NSF/ANSI standard 42 in these 3 posts as much as possible for the layperson. Hopefully, you now have a clearer idea what this standard is all about.

Good luck!

Figure: A few rare filter housings I have seen