Water filters: do you need one?

Tap water is one of our most important basic necessities. And generally, most Australians don’t have to worry about getting sick from the water they’re supplied with. The Australian Drinking Water Guidelines specify that water “should contain no harmful concentrations of chemicals or pathogenic micro-organisms, and ideally it should be aesthetically pleasing in regard to appearance, taste and odour.”

Water authorities use settling, coagulation, filtering and disinfecting to ensure the safety of our drinking water, using sufficient disinfectant to stop the re-growth of microorganisms as the water travels through the pipe system to your home.

The downside of ensuring safe drinking water is the lingering taste and smell of disinfectant. If you fill up a jug with tap water and leave it to sit for a couple of hours, the disinfectant smell and taste will gradually dissipate, but many people opt for a water filtering system.

When you turn on your tap, you should see clear, un-cloudy water. If not, or it tastes strange, then there are ways to find out why.

The bottled water industry

Australians spend around $385 million a year on bottled water, and more negative light has been shone on the product lately with regard to its life cycle. It takes so much energy to obtain the water from the source and produce the bottles that the water is transported in, plus its transport energy, refrigeration energy and recycling that adds to that energy footprint — though only 35% actually gets recycled. Most bottles end up in the landfill.

Recently councils in some areas have made the decision to discourage the use of bottled water. As the negative aspects of bottled water accrue, the convenience of buying bottled water is becoming less important than taking a few minutes to prepare your own re-usable bottle from the tap or filtered source before heading out.

If there’s a health concern, it shouldn’t be up to individual households to fix it. In a water treatment plant there are engineers, chemists and other experts who make water safe to drink. Talk to your neighbours and your water supplier to find a solution that tackles the source — the treatment plant, the distribution pipes or your home’s plumbing.

However, that may not always be possible — for example, if your supplier doesn’t fix the problem, if you get your water from a small supplier without the resources to do so, or if you have your own supply. In these cases, installing a filter may be your only feasible option. Choose the system that’s best suited for your specific problem. And look for a model that’s certified according to a relevant performance standard.

Look for certification

There may be models that claim to meet these performance standards but aren’t certified (certification costs money, which can be an obstacle for smaller businesses). However, how can you be sure? If you’re treating a potential health threat you have to be able to rely on the filter’s performance — and certification is the best available guarantee.

If you’re not happy with the aesthetics of your tap water (its taste, look or smell), looking for a certified product is still a good idea, but may not be as important. In any case, be aware that a filter can make your water’s quality worse if you don’t use it properly.

Tap water can contain many impurities, both natural and artificial. Some are harmless, or only affect what the water looks, tastes or smells like. Others can give you an immediate infection or slowly damage your health over a long period of time.

Some chemicals (such as chlorine and fluoride) are added to your water in the treatment plant. There are ongoing discussions over potential health risks as a result of this. But the benefits of using the chemicals are still thought to outweigh any potential risk.

Microbiological

Supplying water that's free from pathogenic micro-organisms (those that can make you sick) is the most important task for water authorities.

• Bacteria: Most pathogenic bacteria found in water come from contamination by human or animal faeces. Disinfection (for example with chlorine) usually kills all bacteria. Another potential threat are bacteria growing in the water mains. That's why water suppliers try to ensure there's a residue of chlorine to protect the water on its way from the treatment plant to your home.
• Protozoa: This group includes cryptosporidium and giardia. These can cause severe illness, and their cysts can often resist disinfection.
• Viruses: Some viruses that can be found in water are potentially harmful. While disinfecting the water usually kills most viruses, some may survive and make you sick. However, it's not known how big a problem this is in Australia, as the source of a viral infection (whether it's water, food or contact with another infected person) is difficult to trace.

Chemical

• Pesticides and herbicides can leach into waterways in rural areas. Some are potentially carcinogenic and last in the environment for a long time. While low concentrations of these chemicals have sometimes been found, our drinking water is usually free of them when tested. However, not all water authorities check for them regularly.
• Nitrate/nitrite: The main sources for these chemicals in waterways are sewage and fertiliser run-off. Groundwater supplies in rural areas are most likely to have high nitrate concentrations.
  While nitrate itself is harmless, it can be converted into nitrite, which mainly poses a problem to babies and young children - it can reduce the amount of oxygen the blood can carry. In areas where nitrate is a problem, the water supplier will usually advise people to use bottled or rainwater for children under three months.
• Chlorine and chlorination by-products: Chlorine or chloramine is usually added to kill bugs in the water that passes through the treatment plant, and to protect against recontamination while the water's travelling through the distribution system.
  However, these chemicals can - depending on a number of parameters - react with naturally occurring organic substances in the water to form potentially harmful by-products (mainly so-called trihalomethanes, THM).
  The drinking water guidelines state a maximum concentration for these by-products. They also point out that while their concentration should be minimised, the disinfection of drinking water must not be compromised. The risk posed by by-products is considerably smaller than that posed by the presence of pathogenic micro-organisms.
• Fluoride has been added to drinking water since the 1960s and '70s as it has a proven record of reducing tooth decay.
  However, fluoride protection is now available from more sources - for example, from many toothpastes or from fluoride treatments applied by your dentist. Critics say fluoridated water is unnecessary, as it may lead to dental fluorosis (mottled teeth) in people who get too much, and we don't know the potential health risk of drinking fluoridated water over a lifetime.
• Aluminium: Chemicals containing aluminium are used in a process called flocculation, which removes suspended particles from the water, making it clearer. While most of the aluminium used can be filtered out of the water, small amounts may pass through. Some water authorities have phased out the use of aluminium chemicals in favour of alternatives.

• If your water looks, smells or tastes strange, or if your clothing and plumbing (such as sinks and toilets) become stained by it, use our table, below, as a starting point to narrow down the number of possible causes.
• Ask your neighbours whether they have similar concerns. This may help to find out whether it's a general supply problem, or one caused by your home's plumbing.
• Talk to your water supplier about your concerns. If you've recognised a potential problem, tell them — it may help them assess and solve the problem more quickly. Ask them for the latest analytical results of your water supply, and the corresponding Drinking Water Guidelines recommendations.
  If you still have doubts, get a water sample analysed. Your supplier may do that free of charge, especially if there's a health concern.
  Your water supplier may be able to solve some aesthetic problems fairly easily by flushing the mains, while other problems may require more extensive cleaning or repair of the distribution system in your area, or work on your home's plumbing.
• If you've suffered damage (for example, rust-spotted clothes after a wash) you may be able to negotiate compensation from your supplier.

What's the problem?

Except for micro-organisms and lead, most of these contaminants are an aesthetic rather than a health problem, as long as they don't occur in very high concentrations. 

The basic pros and cons of each type of filtering system are included below, as well as a rough estimate of initial costs. Ongoing costs can be determined by checking the volume or time it claims to filter before requiring replacement.

Be sure to factor in the cost of replacement filter cartridges and always replace as instructed, as spent cartridges can themselves harbour microorganisms. What each cartridge can filter varies even within the different types of dispensers.

Jug filter

Prices: $20 - $75 initial

• Pros: Convenient, small, and easy to use and replace filters.
• Cons: Some are slow, prone to clogging and have short filter lives, meaning higher ongoing costs. 

Tap mounted

Prices: $25 - $75 initial

• Pros: Most convenient at tap filter, small, and easy to use and replace filters. Easily swap between filtered and non-filtered water.
• Cons: Slows the flow of water and cannot be used on all taps.

Counter-top

Prices: $60 - $350 initial

• Pros: Filters large amounts of water without plumbing modification. Less likely to clog than jug- or tap-mounted filters.
• Cons: Clutters countertops and cannot be used on all taps.

Under-sink

Prices: $180 - $600 initial

• Pros: Filters large amounts of water without cluttering up countertop, or attaching to existing tap. Less likely to clog than jug- or tap-mounted filters.
• Cons: Takes up under-sink space and requires plumbing modification. Most expensive option.

Other options

You can also buy shower filters or ones built into fridge ice and water systems. These are generally carbon filters.

There is also a whole-house option, but they’re expensive and generally only justified in quite specific situations (for example, if you have a poor-quality water supply).

Filter mediums

All the filter systems above can have different types or combinations of filter mediums. Your choice depends on what you want to filter out.

• Filtration/Adsorption Filtration involves using a substance, typically carbon, to make contaminants adhere to the many pores (like pumice) within the carbon source, also called adsorption. The source of carbon can be coconut, charcoal, ceramic, etc. This helps remove odour, taste and particles in the water.
• Softeners If you have a hard water source, you will notice a build up in kettles, bathtubs and sinks. These are normally a result of large amounts of minerals in your water. A softener medium will reduce the amount of minerals.
• UV Treatment This uses ultraviolet light to disinfect water, however it only works on relatively clear water, otherwise the light doesn’t penetrate sufficiently.
• Reverse-Osmosis This passes water under high pressure through a thin membrane. Most contaminants are physically blocked and washed away. It uses a lot of energy and water; up to 85% of the water can be wasted in the process. However, it does remove a wide range of contaminants.
• Distillation This is also energy-intensive. It boils the water, collecting the condensing water to remove many contaminants, though not all.

Illustrations by Cynthia Nge

How can you be sure these filters do what they say, without proof? One thing to look for is certification. The NSF International provides a range of certifications for products that involve initial and periodic testing:

• NSF 42 covers aesthetic effects such as chlorine, taste, odour and particles.
• NSF 53 covers health effects such as cysts (giardia, cryptosporidium), a range of organic chemicals (such as THM and pesticides) and heavy metals.

The Australian standard AS/NZS4348 covers a wide range of contaminants, such as taste, odour and microbiological and chemical impurities. There are also standards for water softeners (cation exchangers: NSF 44), reverse-osmosis (NSF 58) and distillation (NSF 62) systems.

Your own supply?

If you’re not connected to town water, but use rain or bore water, it’s important to protect your supply from contamination — particularly with bore water — and inspect it regularly.

For example, an animal carcass close to your bore can be a serious health threat, and herbicides or fertilisers may over time leach into your water supply. A dirty roof, peeling paint or bird droppings can affect the quality of collected rain water. Many water authorities or your local health department have brochures on what to look for, and how to maintain a storage tank.

Have your water supply tested regularly; contact your local or state health department. It may check the water body you’re drawing from as part of its own monitoring program, or it can test your water — in many cases free of charge if you have a health concern. It’ll also be able to advise you on how to rectify a problem. As a last resort you may want to consider buying a suitable water filter.