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.