Friday, November 19, 2010

Do we really need water filters 2?

Here is a follow-up to the previous post.

Thanks very much for your very detailed explanations.

Just wonder, since "New Water" is quite pure and will be gradually added to our reservoir, how can consumers be protected from any harmful effect that it might bring about ?  Is water filter one of the solutions ?  Any other ways ?

I would not worry about any harmful effects from Newater. Newater is produced by treating the effluent from water reclamation plants using microfiltration, reverse osmosis and UV disinfection. Most (but not all of course) impurities e.g. salts, metals, organic compounds, would have been removed. This is probably already very close to pure water. Anyway, we are not drinking Newater straight unless you have accumulated cartons of Newater and drink exclusively from them. As you pointed out, Newater is mixed in a small percentage with reservoir water so I will worry more about other sources of contaminants.

I missed out a point in the previous post. The water from the water works is routinely tested and compared against WHO (World Health Organisation) drinking water guidelines. Let's assume that the WHO guidelines are adequate safeguards of the water's suitability for drinking, does this mean that water from the tap should be good to drink? Perhaps not because most of the testing and sampling are done right at the output from the water works. The water from the water works then has to flow through a complicated distribution network before reaching your home.

How many of us routinely test the water from our taps? Is there leakage along the way between the water water and our tap? Could the water have come into contact with sewage which may have also leaked from sewage lines? Or perhaps other contaminants have entered the cracks in the lines? What about the pipes and fixtures themselves? Lead, copper, zinc from old pipes could have gone into the water as the pipes corrode. All these scenarios can be real.

Is there other info that might help consumers in their cost benefit analysis as water filters incur recurring cost.

Our drinking water and sanitary standards are considered quite impressive compared to many countries. We do not have epidemics of cholera, typhoid or dysentry as seen in some developing countries or cases of severe heavy metal poisoning that turns whole villages into a public health nightmare. Therefore, most of our concerns are on potential or unconfirmed long term health effects e.g. chlorine, fluoride (update: check out Fluoride Action Network for arguments against fluoridation). This of course makes a quantitative analysis of costs and benefits difficult. For example, how do you quantify the cost of a cancer that may or may not manifest in 30 years time? I suppose the best we can do is a qualitative analysis. Is the risk of cancer (in 30 years time) worth the $300 you spend per year in water filters? Or perhaps is that $300 worth the peace of mind you get from filtering your drinking water? Obviously different people will have different opinions here.

Also, Is there any independent studies being conducted on the water filters and do they really live up to what they had claimed ?

The most widely used standards I have come across are the NSF/ANSI (National Sanitary Foundation International/ American National Standards Insitute) standards. (Other countries e.g. Japan also have their own standards for water filters. Ditto for other organisations such as USEPA and American Red Cross which certify/approve various water treatment units though some of these units are for outdoors use. Update to the update: USEPA DOES NOT test or approve filters. It apparently registers filters though.) NSF/ANSI 42 applies to improvement of aesthetic effects in drinking water using a filter while NSF/ANSI 53 applies to mitigation of health effects from contaminants in drinking water. Water filters can be certified under either or both of these standards though if you are more concerned about your health, NSF/ANSI 53 will be more useful.

However, even if a water filter is certified under these standards, do check the kind of water quality parameters it is tested against. One filter may lay claim to reduction of turbidity and bacteria while another may be certified to reduce only iron and hydrogen sulphide. These are the fine points most consumers will miss out. (Even the sales staff may not be knowledgeable enough.) Make sure you know what contaminants you are concerned about and check whether your water filter is certified to remove those contaminants.

To complicate things a bit more, these standards can apply to the filter component (cartridge or element) itself or the whole system (filter housing + cartridge). Even though a filter element is certified, if the housing has a leakage, the filtered water can be cross contaminated by the inflow. If possible, get a filter that is certified as a whole system and not just the cartridge itself.
(Update by author: The current NSF/ANSI standard apparently does certify the system itself to be structurally sound and does not add anything harmful into the water.)

On a final note, an uncertified filter does not necessarily means that it performs poorly. Remember, certification costs money and that cost will certainly be reflected in the price of the filter.

By the way, may I know which is the Doulton gravity filter you are referring to as they had quite a few models ?

The model that I have is the stainless steel gravity filter, STS-S-ATC ( which uses the ATC Super Sterasyl filter element ( It is the smallest model available here (I have seen a smaller one sold overseas though) so if you have a big family, it may not be enough. Also note that the ATC Super Sterasyl filter element is designed to remove microbes, particulates, metals, organics, chlorine etc. It is very versatile but that comes at a price (monetary and otherwise). Besides the higher price, its filtration capacity is reduced compared to the other filter elements from Doulton. If you are chiefly concerned about chlorine, you can consider getting the STS-SS10 ( instead.

I personally advocate getting a gravity filter because of its beauty in operating without electricity and water pressure. However, it can be a pain to keep scooping water into the filter and pouring out the filtrate from the lower chamber. If you find this too painful, you can consider getting a counter-top (model: HCP-Single) or under-sink (model: HIP-Single) housing incorporating the Supercarb filter element (or candle as they call it) ( (Their webpage shows the above models fixed with their Ultracarb filter element which is higher end. I suppose if you ask for the Supercarb, the price should be lower.)

Thanks & Regards.

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