How a Water Filtration System WorksPitcher Filters and Tap-Based Filters A Brita-style filter that attaches to your faucet, or a pitcher filter uses fewer materials upfront, but requires replacement cartridges. Brita now recycles cartridges, whereas many companies such as Pur still don't.
You can bypass the issue of recycling cartridges altogether by refilling your own. Most of these use activated carbon, which is carbon that has a slight electro-positive charge added to it so that it's even more attractive to chemicals and impurities. As water filters through the carbon, the negative ions of the contaminants are drawn to the surface of the carbon granules, and stick with the carbon instead of the water, giving your purified water out the other side of the filter.
Whole-House Filtration Systems
A whole-house water filtration system requires more materials upfront, but doesn't require the same level of materials replacement. Over the long run, the two tend to even out. A whole house filtration system purifies water throughout the house, from kitchen and bathroom faucets to toilets and laundry pipes. So anywhere water is used in the house, it is treated.
There are a few types of filtration systems used for whole-house. The most common are carbon filtration and reverse osmosis. The two types remove different containments, so your choice depends on what you find in reading your municipal water quality report. Reverse osmosis uses a membrane to filter water, leaving contaiminents on one side of the membrane, and letting cleansed water through to the other side. Both typically require filter changes, though some systems have a self-cleaning filter that eliminates that need.
Cost and Types of Tap- or Pitcher Water Filtration SystemsThere are two main types of sink filters - pitchers and tap-based. With a pitcher filter, you pour water into the top half of the unit, the water drips through a carbon filter, the contaminants stick to the carbon and the clean water drips down to the bottom half of the unit. You can then pour right from the pitcher. A tap based filter screws on to your faucet. You can adjust it to an on or off position. When adjusted to an on position, water from the faucet runs through a carbon filter before coming out the other side into your glass.
A pitcher filter like Brita runs about $25 with three filter, and refills are about $30 for a 5-pack. An on-tap filter and refill filters run about the same price. The filters will last about a month. So an average annual cost is about $85 for the first year, and $71 for successive years, provided your pitcher or tap filter system stay in tact for awhile. You can cut that cost by refilling your filters yourself.
More expensive up front at $40, but of a very high quality, is the ZeroWater pitcher filter. It is certified to meet the highest standards for removal of lead, iron, zinc, and mercury, and was tested and shown to remove antibiotics, hormones and perchlorate. The company recycles its filters, and is working on a redesign of the filter so that it can be taken apart and refilled easily.
Measuring the environmental cost is a more difficult job, since the numbers aren't readily available to compare. However, there are some tools. Appropedia provides a carbon footprint worksheet to determine your carbon footprint when you use either Brita or Multi-Pure. You can use this tool for these two filters, and for other types, take the factors laid out in the sheet - such as your distance from the manufacturing facilities, your distance to the recycling facilities for the filters, how often you plan to recycle the filters and so on - and apply them to the other filters. It takes a whole lot of research an calculation, but if you're really curious, could help you determine if there is a significant carbon footprint difference between the filters you're considering.
Cost and Types of Whole-House Water Filtration SystemsA whole-house filtration system varies significantly depending on the type and size of the system. It depends on if you get under-the-sink systems, that purify the water going just to that outlet, or a system that purifies the water going into the entire house. While costs vary greatly, an average price for whole-house is between $1,500 and $3,000 if you purchase the system outright. Under-the-sink filtration systems can be quite a bit lower in cost - averaging between $300 and $500 - and it doesn't waste resources filtering toilet water or laundry water, which you may not need it to do anyway.
The filters usually last quite a bit longer than pitcher filters, as long as six months, or some don't need replacing at all, cutting down the cost significantly. Also, some systems like those that use reverse osmosis can be wasteful of water. You can get a listing of Gold Star Rated products by the Water Quality Association to help you make a decision.
Conclusion: Choosing the Best Water Filter for YouIf the water in your area is already decently clean and you don't have an issue with the taste, then you can reasonably skip the filter altogether for the lightest footprint.
If you're concerned about the taste and a few possible contaminents that your water quality report says may be in the system, it's better to keep the smaller environmental footprint of using just a pitcher- or faucet- water filter for your drinking water needs, since washing, bathing and laundering with already good quality would be a waste of water filtration equipment. When a Brita or Pur cartridge can last anywhere from 1-3 months, the use of this method for drinking and cooking purposes works perfectly well.
If you're in an area where water quality is on the poorer side and you need cleaner water for use around the house, then it is worth investing in a whole-house filtration system since, in the long run, it will be more efficient and lower impact than a big pile of Brita filter cartridges.
Ultimately, a return to the tap is necessary, and thankfully in many instances you'll find that a water filter isn't really needed. But if it's better taste you're after, or have a real need to clean up your water supply, you have a solid selection of choices in front of you.
More on Water Filtration and Going Back to the Tap
Back To The Tap: Three Ways To Get Fancy Water, And Skip The Plastic Bottle
What's in the Water? Ask the National Tap Water Quality Database
Graham Asks: Can I drink the Water in New York City?
Great Chefs Prefer Tap Water