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.

Ready...?

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...

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/
 



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.

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.

Warmly

Paloma 

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.

Cost
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.

Microbes
"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.

Output
"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.

Verdict?
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.


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.