Road Test: Water Filters
It’s said that London’s water passes through 13 people before being flushed into the sea. For many of us in the UK, the water does certainly taste ‘used’. But taste isn’t the only problem. Tapwater also contains pollutants such as fluoride (natural and artificial), lead (from old pipework), Giardia (an intestinal parasite), nitrates, pesticides, hormones and drug residues. Yet, most health authorities firmly deny that there are health problems linked to drinking it.
While tapwater may not house the nastiest bacteria or viruses, it does contain the toxic chemicals used to kill such bugs. The best-known one – which consumers can taste (and even smell) – is chlorine. Chlorine combined with organic matter or certain naturally occurring chemicals in water forms trihalomethanes and other harmful disinfection byproducts (DBPs). Our drinking water accounts for a major part of our total exposure to DBPs, followed by air and food (Foundation for Water Research Report No FR0290, March 1992).
But, amazingly, given its link to poor health, the amount of chlorine in water is not regulated in the UK. A 2000 World Health Organization report recommended no more than 0.5 ppm (parts per million), above which levels the United Nations agrees is “unacceptable” to taste (UNHCR Manual, August 2002). Thames Water, the largest water and sewerage company in the UK, reports that their chlorine levels are 0.33-0.51 ppm
In the lab and in animals, DBPs show cancer- and mutation-causing effects, and epidemiological surveys confirm that DBPs may be a menace in people, too.
While killing bacteria, chlorination also kills cells in the body. The US Environmental Protection Agency (EPA) says that chronic exposure to chlorine and its byproducts can cause liver, kidney, heart and nerve damage, and even cancer (J Natl Cancer Inst, 1993; 85: 817-22).
Indeed, the risk of bladder cancer is doubled by DBPs, and US scientists estimate that up to 17 per cent of such cases are due to DBPs in tapwater. An Iowa study found that those living in areas with high levels of DBPs in the water had nearly twice the colon-cancer rate of low DBP areas (Am J Public Health, 1997; 87: 1168-76).
DBPs are also a hazard in pregnancy. A review of more than 80,000 births during 1985-1988 found that women who regularly ingested water with high levels of DBPs were more likely to have babies with low birth weights and abnormalities (Am J Epidemiol, 1995; 141: 850-62). Miscarriages are twice as likely in areas with high DBPs (over 75 parts per billion) (Epidemiology, 1998; 9: 134-40) – yet, the UK maximum allowable DBPs are 100 ppb. A study by Imperial College London showed that DBPs in British tapwater can significantly increase the risk of stillbirths or low-weight babies (J Expo Anal Environ Epidemiol, 2004; doi:10.1038/sj.jea.7500380).
Male fertility, too, is at risk, as sperm can be severely damaged by DBPs (Reprod Toxicol, 1995; 9: 571-8).
More worrying still, we don’t just ingest DBPs from drinking water. Taking a bath or shower also exposes the body to high levels. A 10-minute shower can leave more DBPs in the blood than drinking a litre of tapwater (J Expo Anal Environ Epidemiol, 2000; 10: 321-6). This is because heat vaporises the chemicals, allowing them easier access to the lungs and bloodstream.
Crystal clear?
Turbidity or cloudiness indicates particles of clay, silt and decaying plants, even parasites, which may all be magnets for disease-causing microorganisms. Being chemically bound to the particles, they escape chlorination. According to Dr Joel Schwartz, of Harvard School of Public Health, “10 per cent of gastrointestinal illnesses in children and the elderly may be due to turbidity in ordinary tapwater “.
The gut parasite Cryptosporidium enters the water supply mostly via the run-off from farms, and is impossible to eradicate by chlorination. It can cause anything from flu-like symptoms to death, depending on your state of health. In 1993, an outbreak in the US hospitalised more than 4000 people and killed 50 – mainly infants and the elderly. In the UK, the parasite in tapwater causes hundreds of cases of diarrhoeal disease each year.
Intensive farming is largely responsible for the nitrates and pesticides in our water. Regulatory authorities require water companies to remove them, but not entirely, so there is always a measurable amount left in drinking water. The permitted residue levels are believed to be safe, but how can anyone really know? As with most public health matters, we are all guinea pigs.
The products
Tapwater isn’t clean and bottled waters aren’t necessarily better (see PROOF! vol 7 no 12). So, if you’re after pure water, you may have to use a water filter.
There are several types of water filter, with different filtration characteristics and pricetags. The simplest is the tabletop jug filter, using a carbon-based cartridge to filter the water. Other countertop units use gravity or distillation. You can also buy units that fit directly onto the tap, and use a carbon, ceramic or microporous membrane to filter out impurities.
Reverse osmosis uses a potentially bulky piece of plumbed-in technology. Tapwater runs through a 5-micron prefilter, then a semipermeable membrane to separate out smaller contaminants; half the water is used to flush those away, and the rest is stored as drinking water. This is wasteful and removes beneficial minerals along with the nasty stuff. It is also mildly acidic, which may have long-term adverse health consequences.
We’ve taken a representative sample of the hundreds of water filters on the market, plus a handful of other water treatment methods, and rated them according to function, simplicity and cost.
GS2 Gravity Water Purifier
Distributor: Fresh Water Filter Co Ltd
Price: lb95.00
Rating: *****
Large but portable, this countertop filter system produces 9 L of water with two six-stage filter cartridges, using a 0.5-micron membrane – serious filter power that removes all heavy metals, pesticides, chlorine, DBPs, Cryptosporidium, phenols and solvents – but retains beneficial trace minerals and fluoride (but there ‘s an extra filter for removing fluoride). It takes an hour to filter 1 L of water.
Pozzani IX 600
Manufacturer: Pozzani Pure Water plc
Price: lb70.00
Rating: ****
Pozzani is a British company that’s been making water filters for over 70 years. This is one of the cheapest plumbed-in systems on the market, and a relatively simple DIY job to fit. The filtration system is a single cartridge, using a membrane, an activated carbon plus ion-exchange resin and a carbon block. It gets rid of up to 95 per cent of most heavy metals (lead, aluminium, iron, copper and cadmium), 90 per cent of organic material (such as pesticides and DBPs) and almost all chlorine.
Its advantage over countertop systems (and reverse osmosis) is that it produces a constant flow of water (about 3 L/min). But, to get a fast waterflow, the membrane has relatively large holes (5-micron diameter), which may not remove all Cryptosporidium. (If this poses a problem, Pozzani ‘s IX 250 does a more thorough job.)
DomSource
Distributor: h20 Living
Price: lb59.95
Rating: ***
This Japanese device fits directly onto the cold tap, and has three settings: filtered, unfiltered (for washing-up) and shower. It uses an activated-carbon filter and a membrane with extremely fine (less than 0.1 micron) holes, and claims to remove all bacteria, turbidity and Cryptosporidium – but no dissolved minerals, good or bad. That means your kettle will still go fuzzy and your water will retain fluoride and nitrates. Each cartridge lasts for 2000 L, or about four months (see table, page 3).
ACVRO35 4-Stage Reverse Osmosis
Distributor: H2Onics
Price: lb219.95
Rating: ***
This claims to remove “up to 98 per cent contaminants”, by which they mean the usual culprits. This includes fluoride, but it takes out all trace elements, too. A DIY under-the-sink installation, like all reverse osmosis (RO) kits, it needs more space than other filter systems, requiring a separate storage tank. With a 9-L capacity, it ‘s the best value RO kit in our survey.
KRO Plus Deluxe GX
Manufacturer: Kinetico UK Ltd
Price: lb639.20
Rating: ***
Costly for what appears to be a standard RO kit, it has a final filter that “provides an extra polish” after the storage stage; the filter also shuts down automatically when it needs to be renewed. The standard-sized (11.3 L) storage tank may be too big for most homes, but there ‘s a space-saver (3.8 L) option. Kinetico claims that using mains pressure ensures a quicker, more consistent, flow rate than other RO units.
Brita Atlantis
Distributor: Brita UK
Price: lb17.49
Rating: **
The simplest and most well-known filter system, this is a water jug with a filter on top. The filter comprises activated carbon particles that absorb chemicals, plus a resin that binds to the ions in minerals such as calcium. The Atlantis can eliminate limescale but, theoretically, other minerals in the water will be lost, too.
Apart from limiting the amount of water you can get at any one time (2.2 L, although Brita does make a 5.5-L model, the Optimax), the downside is that jugs don ‘t get rid of all the nasties in tapwater: it removes only 85 per cent of chlorine and not all pesticides, and no fluoride or nitrates. You also need to change the filter at least once a month to maintain its efficiency. The Atlantis has an in-built timer to remind you to do this.
Purwa Water Distiller
Manufacturer: Fresh Water Filter Co
Price: lb235.00
Rating: **
If you’re after 100-per-cent guaranteed contaminant-free water, this is the one for you. This product, which has a tank capacity of 4 L, offers nothing but distilled water, made in the time-honoured way of condensing steam and passing it through a final carbon filter to improve the taste.
You simply pour your tapwater into the device, which boils it and turns the steam into water. The result is no pesticides, no DBPs, no nitrates, no bacteria, no viruses, no minerals, no oxygen – nothing but chemically pure H20 and, some would say, no taste.
If you’re prepared to put up with that, you probably won’t mind having to wait the hour and a half to get just 1 L of water out of it.
It may appeal to very sick people with compromised immune systems but, even then, it may have negative health consequences as the water is slightly acidic.
Living Water Vortex Jug
Distributor: Sulis Health
Price: lb59.50
Rating: *
A must-have bit of kit for fans of Viktor Shauberger, the 19th-century Austrian water guru. He believed that water gets its quality and vitality from constant movement, such as in mountain streams. This 2-L jug is based on a Schauberger invention, in which water is spun into vortices by a simple propeller. While it ‘s pretty to look at, it’s unlikely to do much more than oxygenate the water, and even Sulis acknowledges its limitations. “Although the Living Water Vortex Jug does a lot to purify tap water,” they say, “we do recommend the use of a filter that will remove heavy metals and pernicious chemicals. ”
Vivatap
Distributor: Brunel Healthcare
Price: lb2.99 for 18 sachets
Rating: *
Although not exactly a water filter, this product claims to “improve the taste and quality of drinking water”. It’s as easy to use as a tea bag, which it resembles. You simply drop a sachet into a jug of water, wait a few minutes and, hey presto!, it “instantly removes all chlorine”. That’s a major claim to make, and usually achieved only by the most powerful filters.
Vitatap also claims to “adjust” acidity (with coral algae), and “reduce bacteria” (using chitosan). These two extra ingredients “may” also add minerals and reduce mercury. One sachet will treat 2 L of water.
Available from Boots, this is a product with too many question marks to rank alongside genuine water filters, although it probably will reduce the taste of chlorine and so may be worth a try. But if getting rid of the chlorine taste is all you ‘re after, just standing a jug of tapwater in the fridge overnight should also remove the offending flavour.
- This article first appeared in the October 2004 edition of Proof!.
