Whatever happened to good old city tap water?
Home water filters can help remove contaminants or unwanted chemicals from your tap water, but before you invest in one, make sure you understand what they do, and whether you really need one. If you read the marketing materials from some of the manufacturers – or from other websites purporting to provide unbiased information on in-house filtration systems (but making a hefty commission from any you might buy from them) – you would think our water supply is beyond redemption and that the cancer and heart disease epidemics that have plagued us for decades are all caused by how we treat (or fail to treat) our water!
It’s true that if your water is from a municipal supply, it likely contains chlorine, which can react with organic chemicals also present in the water, to form carcinogenic compounds such as haloacetic acids and trihalomethanes. However, the chlorine in water supplies is extremely low – 3 parts per million or lower – and municipal water suppliers constantly monitor their output to ensure the concentrations of these compounds are well below danger levels. The chlorine can give tap water an unpleasant taste, but you can easily address this by filling a pitcher with water and leaving it out for a few hours – or in the refrigerator – by which time most of the chlorine will have evaporated.
Your tap water may also contain other contaminants, such as lead (from old lead pipes in your municipal water supply or your own pipes), mercury (a byproduct of coal burning, as well as of waterlogged wood, for those whose water supply comes from a northern lake or a flooded reservoir), and the pandora’s box of manufactured chemicals that we rely on for many of our day to day comforts. Then again, it’s not clear whether any of this will make you ill; it may be that worrying about what’s in your water supply is more harmful to your health than just drinking the damn stuff. I’ve drunk tap water straight for most of my fifty years and I feel just fine so far!
Types of water filter systems
Let’s start with an overview of the three main types of home water filters, before we go into depth on each.
Drinking water filters are the home water filters that get the most attention. Considering all the contaminants I listed above, it shouldn’t surprise us that people want to avoid ingesting all that stuff, and if you insist on not drinking straight form a regular tap, then filtering your drinking water is the way to go – it’s certainly more affordable and environmentally friendly than buying bottled water, for example!
Shower water filters attach directly to the plumbing for your shower, and their main purpose is to remove chlorine from your shower water. Some also claim to reduce the hardness of shower water, although the evidence for these claims is at times sketchy. There are two main benefits of removing chlorine from your shower water: it’s not good for your lungs to breathe chlorine gas, which you do a lot of in the shower; and some people report reduced incidences of skin and hair health issues when showering with chlorine-free water.
Whole house water filters connect to your water at the house intake, and filter out chlorine and other chemicals, and potentially purify the water too (removing pathogens). These home water filters have a lower cost per gallon than home water filters designed just for drinking water. Then again you’ll be filtering a lot more water.
Drinking water filters
If I were to invest in any home water filters I would start by looking at drinking water filters – there is a wide range of choices at low entry price points, and, health benefits aside, the chlorine taste of municipal tap water can get pretty strong sometimes. There are four main types of drinking water filters:
Pitchers typically cost $15 to $40 and consist of a polyacrylic or other clear plastic pitcher, an upper reservoir into which you pour unfiltered water, and a filter medium through which the tap water passes through into the main section of the pitcher below. Pitcher home water filters typically have an activated charcoal filter system, which is good at removing chlorine and lead and some other contaminants. One of the main drawbacks of pitchers is that the filters are relatively short-lived and need to be replaced every month or so, adding to your expense and to the environmental burden at landfills.
Countertop containers are similar to pitcher-based filters, but stay in one place and hold two to five times more water. You fill them from above and they usually have a spigot at the front from which you can dispense filtered water. Typical prices for countertop containers are in the $30 to $150 range, and the same types of filter media are typically used (so some of the same cost issues apply.
Faucet attachment water filters attach directly to a faucet (typically that in your kitchen). Their price range is similar to that for countertop container filters ($30-150). Their advantage over pitchers and countertop containers is that you can have filtered water whenever you need it without having to store large quantities of it. Their main drawbacks are (A) that they are plumbed in (typically by screwing onto the end of your faucet where the aerator would go), and so you can damage the faucet or experience leaks at the seal when the filter is in use, and (B) they don’t usually look very attractive.
Under-sink home water filters are a more expensive but more aesthetically pleasing choice, because all you see above the counter is a small spigot. They range in price from $60 to $600, and can consist of a single, double, or triple filtration system or a reverse osmosis system. I would not recommend reverse osmosis home water filters unless you have particularly troublesome water to start with, or are particularly sensitive to chemical contaminants (for instance if you have an immune system disorder) because these systems are quite wasteful, because of the physics of the process: in a home reverse osmosis system, between 50% and 80% of the water used to produce your drinking water is discarded. If you’re only filtering enough water for drinking, the waste is not a major factor, since other areas of your home (shower/bath, toilet, laundry) will use a lot more water than the little being wasted here. But if you plan to use it for all cooking as well (for example, boiling your pasta or potatoes in filtered water) you’ll be producing a fair bit of waste water. The two other issues with reverse osmosis systems are energy use and propensity to spring leaks. Reverse osmosis works by pushing water against a membrane that only allows water molecules and other very small molecules through it; this high pressure typically requires a pump, so there is some energy cost to it; and the high pressure increases the likelihood of leaks in the system. (Friends of mine who have a reverse osmosis under-sink filter system keep a washbasin underneath it at all times because it has sprung so many leaks!)
Shower water filters
There’s a great deal of panic-mongering on websites that would like to sell you home water filters for every possible water use. While it’s true that some chlorine disinfection by-products (CBPs) are known or suspected carcinogens, the levels of these chemicals in most municipal water supplies are kept far below the level that pose any significant health risk.
When you shower, most of these CBPs do not enter your body because they are in dissolved solid form or liquid form and simply wash off along with the water. But you do need to worry about the chlorine itself, which evaporates from the water as it comes out of the showerhead. Breathing this chlorine in fact poses a greater risk to your health than drinking chlorinated water.
But is the risk that great? Consider the overall likelihood of developing cancer in the US, which is approximately two people out of every 1,000 people (1.931/1000 is the exact figure). According to the US Centers for Disease Control, the added risk of developing cancer due to inhalation of chlorine based compounds while showering is only 0.24 cancers per 1,000,000 people per year, which is equal to 0.00024 cancers per 1,000 people. Thus your risk rises from 1.931 / 1,000, to 1.93124.
Most shower water filters remove some, but not all, of the chlorine. A typical reduction rate is 70-80%, so we might assume this reduces your cancer risk from 0.24 per 1,000,000 people, to 0.05 per 1,000,000. Again, these numbers are so tiny it is just not worth worrying about them. Your health will benefit far more from ensuring you have a regular exercise regime, a healthy diet, and a worry-free life!
Shower water filters come as specialized hand-held showerheads (where the filter is built into the showerhead) or as cartridges you insert between the hose or wall pipe and the showerhead. Typical costs are $10-30 per filter and a filter typically lasts about 6 months. People who use these filters report a reduced odor of chlorine, and in some cases a reduction in skin and hair health problems, in particular a reduction in acne or psoriasis, itching, and hair brittleness. However, you can probably do your body a lot more good by simply not showering every single day – or at least avoiding using soap every day – than by removing the chlorine from your shower water. Our skin naturally produces oils to protect us from drying out. When we keep scrubbing at our skin and shampooing our hair on a daily basis, we remove those oils, and our skin dries out as a result. So it may not be the chlorine that is causing skin and hair problems for some – it may be their obsession with showering!
Magnetic shower filters are another type of home water filters that claim to remove scale and de-ionize or soften water, but in my opinion this is pseudoscience and hype, you are paying for something that will do absolutely nothign for you. It might seem at first that it works – because you want to believe the $100 showerhead filter you just bought is worth what you paid – but if you do an objective assessment of what’s changed, I doubt you’ll find much. See Magnetic water treatment pseudoscience for an overview of the physics of magnetic water treatment and why there’s no real evidence it works.
Whole house water filters
Whole house filters range in price from $500 to $2000 and have capacities of 75,000 to 750,000 gallons. They typically consist of a triple filter system: The first filter is a sediment filter that removes larger solids (5-10 microns and larger) from the water, the second filter removes smaller solids and chemically traps much of the chlorine and other chemicals, while the third filter is an activated charcoal filter that removes the last of the chlorine and other organic chemicals. Some whole home water filters are large single-column systems that still remove a large range of contaminants (but are designed for homes already on a municipal water supply).
Whole home water filters can be expensive to operate when you consider how much water you use in a month, compared to how much of that water really needs to be filtered. For example, up to 30% of household water consumption comes from toilet use. There is really no benefit to filtering the water going down your toilet. And as I’ve suggested above, while there is some risk associated with inhaling chlorine while showering or bathing, the increased risk is very slight, so I ascribe little benefit to filtering water for bathing. It’s doubtful that filtering chlorine from your water will have much impact on your laundry either – unless your municipal supply is over-chlorinating the water. Your dishwasher also doesn’t much care about the chlorine in your water. So in essence, you are filtering 100% of your household water in order to minimize the health impacts of perhaps 5-10% of the water in total.
Remember – what goes down must go up
It’s important to remember that our water supply needs filtering mainly because of what we humans have done to our groundwater and surface water ways over the last hundred or so years. All the chemicals we use in farming, in manufacturing, in our own households, eventually work their way downstream – washed off the fields, drained out of settling ponds, washed down the kitchen sink, flushed down the toilet. If we all did more to cut back on the bad stuff that gets into our water supply in the first place, we wouldn’t have to worry so much about the quality of the water coming out of our taps, and home water filters would be of no value for most of us.
That’s the main reason I am not a big fan of home water filters. It takes substantial additional energy to manufacture the filters, housings, containers, and other paraphernalia required to make a home water filter work. Many of the materials these products are made of involve the production of harmful byproducts (for example in plastics production). Some types of home water filters actually waste far more water than they filter (namely, reverse osmosis systems). And the media typically wind up in the trash. I don’t deny that there are places where there’s a real need. The water at my parents’ cottage, for example, is undrinkable if not filtered. I don’t deny that there are people who truly need filtered water, such as a friend of mine who has had major health problems for two decades and needs to cut back on every possible potential source of toxins in her life. But for most of us, clean, chlorinated tap water is a pretty good option.