By Debra Tan 13 December, 2011
To filter or not to filter and which filter? The two key questions on water for the home. Mona Ip tackles these
I’ve just signed a one-year maintenance contract for the “CMB” Reverse Osmosis water filtration system at my new place. I trust my friend whose apartment I’m renting, as she is a switched-on gal who must have researched her options before purchasing the system (I think?). As a super water guzzler, I believe it certainly beats buying water by the bottle1.
A few days later, I attend a morning meeting where I come across a Canadian water filtration technology that is “inspired by nature” and doesn’t remove all the healthy minerals – unlike reverse osmosis, which essentially purifies water. Swayed by this argument and the curvy, egg-shaped unit, I wonder whether I will get enough minerals from my water at home. As I attempt to rationalize my choice of the reverse osmosis system, I realize that I have no idea what I am trying to filter out of the water or into my body, nor do I know anything about the state of my water quality2…
Get informed – “Hong Kong enjoys one of the safest water supplies in the world”
In fact, Hong Kong’s Water Supplies Department (WSD) has a comprehensive and effective freshwater treatment and monitoring programme. Through stringent sampling at treatment works, distribution networks and customer’s taps, WSD assures us that Hong Kong’s water conforms to the World Health Organization’s Guidelines for Drinking-Water Quality 3.
Since the water is also affected by plumbing conditions of individual buildings, WSD does not guarantee quality at the tap. Certainly, the condition and maintenance or lack thereof of your building’s internal pipes, water pumps and water tank will impact your tap water – for instance, the usual culprit for discoloured water is rusty piping. Nonetheless, most Hong Kong buildings are well maintained and it’s very rare that anyone gets sick from drinking water. Experts concur that Hong Kong’s tap water is pretty good overall.
To filter or not to filter
So if our tap water is safe and healthy to drink, why do we bother with boiling and/or filtering4? Interestingly, WSD actually recommends against the installation of any domestic water filters, as domestic water filters can become an ideal breeding ground for bacterial growth if not properly maintained5.
According to Blake Ireland, the Managing Director of a local water filtration company Life Solutions www.lifesolutions.com.hk, filtration for Hong Kongers is really a personal choice. He offers two key reasons why we choose to filter:
1) Perception – many people perceive that Hong Kong’s tap water is not very good quality, particularly the elder generation as they were coloured by problems with water quality in the past and are accustomed to boiling water before drinking.
2) Taste – WSD maintains residual chlorine in our water to ensure that it is not contaminated during distribution and delivery. Even though such small amounts of chlorine are not harmful to human health, the water can end up with a nasty smell and taste, which contributes to our perception of poor water quality.
Ireland claims that the Chinese tradition of boiling drinking water is a waste of time and energy. “To kill all bacteria, you need to boil at 160° for 2 hours continuously, in a vacuum” says Ireland. Moreover, the bacteria present in Hong Kong tap water are not generally harmful to human health. That being said, boiling water is effective at removing chlorine so water “tastes better and is assumed to be better quality”.
Home filtration options
So what options should I have explored before I went ahead to sign the contract for my filtration system? The Consumer Council in Hong Kong tells us that in choosing a water filter, you should try to understand the filter’s removal capability and the contaminants that you want to remove. Target your specific problem and take into account the price and availability of replacement cartridges or filters6.
Here is a summary of three popular options for home water filtration:
|Micro-filtration||Uses carbon and/or ceramic filters to take away large sediment and generally absorbs chlorine, pesticides and organic pollutants. May improve taste through softening water and eliminating odours and discoloration. Some carbon/ceramic filters are treated with silver to help incapacitate bacteria and prevent mould and algae growth in the body of the filter. Carafe (e.g. Brita) and faucet-mounted micro-filtration are popular options due to relatively low costs and easy installation.|
|Ultra violet radiation||Uses high frequency light to irradiate water and kill organic matter such as bacteria, viruses, moulds, algae, yeast, etc. Although UV treatment is not actually a filter, it can be applied together with micro-filtration in order to remove other contaminants. Often applied for whole house systems and in the food and beverage industry.|
|Membrane technology/ reverse osmosis||Removes the widest range of contaminants including dissolved solids and heavy metals, and is the only filtration type certified to remove arsenic7.Depending on source quality, reverse osmosis process creates additional and significant wastewater. Requires professional installation and plumbing modifications.|
The quick and dirty – maintain your filter!
Like WSD, Ireland stresses that all filtration systems need monitoring – if your filter is full or clogged, there is not only potential for bacteria build-up, but contaminants stuck in the filter can backwash into your drinking water. In other words, the “filtered” water you drink could be poorer quality than drinking from the tap if your water filter is not properly maintained. Unfortunately, it is usually impossible for consumers to judge the quality of water themselves and therefore you simply rely on scheduled filter changes, guesswork or regular testing from your filtration company.
What about China?
Aside from areas located directly at spring sources, most places in China don’t enjoy reliable, high quality drinking water. There are alarming problems with both rural and urban domestic water quality, which has deteriorated due to industrialization, animal husbandry, domestic sewage discharge, agricultural chemicals and soil erosion. Due to a lack of controls, regulatory enforcement and widespread treatment facilities, China’s water problems will not be resolved in the short-term8.
The majority of Chinese households have limited means to treat water aside from the traditional boiling method. Although a few minutes boiling will kill some bacteria, it does nothing to remove dangerous chemicals, industrial pollutants and heavy metals. As Ireland says, “nature’s best filter is the human body. However, heavy metals cannot be filtered out, they stay in your system.”
It’s probably unrealistic for all Chinese homes to adopt reverse osmosis systems, so hopefully standards to treat and monitor domestic water will improve with increased public awareness and pressure. It’s too bad, but I resolve to rely on bottled water when in China AND to really appreciate my tasty water at home. I just need to remember to maintain my filtration system regularly and work harder to conserve water to compensate for the wastage created by reverse osmosis (shorter showers?)9. More ideas on water-saving next time…
1See https://www.chinawaterrisk.org/opinions/just-what-is-bottled-water/ if you are curious about what’s really inside bottled water
2Indeed, minerals are good for human health, but whether you need to get them from your mineral water is highly debatable, especially since the amount of minerals dissolved in water is very small and tends to be difficult to absorb. The quantity of minerals that you obtain from the food you eat is far greater than from the water you drink!
3 See https://www.wsd.gov.hk/en/water_resources/water_quality/index.html for details on WSD monitoring data or https://www.who.int/water_sanitation_health/dwq/guidelines/en/ for full WHO guidelines
4 I was impressed by my reverse osmosis system’s ability to remove heavy metals – but the quantity and kinds of heavy metals in Hong Kong tap water are actually not significant to negatively impact human health.
7 See https://www.lifesolutions.com.hk/FAQ/FAQ5.php for a comparison chart of reverse osmosis filtration compared to other types
8 See https://www.chinawaterrisk.org/big-picture/access-to-clean-water/ and https://www.chinawaterrisk.org/resources/research-reports/water-pollution/ for more information
9 To process Hong Kong tap water, a reverse osmosis system produces roughly the same amount of wastewater as the purified water it produces for your consumption. But if I shorten my shower by one minute, then I can save 10 litres of water – probably a lot more than what I both drink and waste through my R.O. system!!
Read more from Debra Tan →