Many different types of filters are available to consumers. Determining which type is most appropriate for you—or whether you need a filter at all—depends on what functions you want a filter to provide. No filter eliminates all contaminants, so understanding what filters do and do not do is important.
Read the label to see if it is NSF-certified. If it is, you can search NSF’s database to learn more about what a particular model is certified to protect you against. Labels on water filters also typically state the contaminants that are reduced, which can help to guide your choice. Be sure to read labels carefully yourself and verify the manufacturer’s claims with an independent source, as not all sales representatives will be familiar with your needs.
Keep in mind that most brands include many different types of filters. Sales people might be able to help you make an appropriate selection, but remember that they are sometimes paid to sell a particular brand. You should check claims and read the fine print on filter packaging for yourself and ensure that it will work for your purposes before purchasing.
Don’t assume that if the filter removes one contaminant, it also removes others. Filters that remove chemicals often do not effectively remove germs, and vice versa. Some water treatment devices that remove chemicals, such as reverse osmosis, ion exchange, or distillation systems, might also remove fluoride. Children who drink water with levels of fluoride <0.6 ppm might need a fluoride supplement. Check with your child’s pediatrician or dentist for specific recommendations.
The prices of different filtration systems can vary widely, from simple systems that can cost under $20 to complex systems costing hundreds of dollars and requiring professional installation. In addition to the price of purchasing and installing the system, consider the cost, schedule, and ease of maintenance, such as changing filter cartridges. In order to continue to work properly, all water treatment systems require maintenance.
Some filters are slow, while others can filter large amounts of water quickly. If you only need the filter for personal drinking water, you may not need a fast filter.
Filters commonly found in homes and stores include water filter pitchers, end-of-tap or faucet-mounted filters, faucet-integrated (built-in) filters, on-counter filters, under-sink filters, and whole-house treatment units. No filters or treatment systems are 100% effective in removing all contaminants from water, and you need to know what you want your filter to do before you go shopping (see Step 1). Not all filters of a particular type use the same technology, so you should read the label carefully.
This information is designed as a guide for household water treatment, not a recommendation. Before installing a household water treatment system, contact your local health department’s environmental health group for consultation. Download A Guide to Drinking Water Treatment Technologies for HouseHold Use. [PDF – 1 MB]
Different water filters have different functions. Some can make your water taste better, while others can filter out harmful chemicals or germs. No single filter can keep every type of contaminant out of your drinking water, and not everyone needs a water filter.
The water that comes to your tap actually contains small quantities of many other substances. Some of these are beneficial, such as the appropriate amount of a disinfectant, like chlorine, that helps keep your water safe from germs and fluoride, which helps prevent tooth decay. Other substances that might be in water can be harmful, such as lead and the germ Cryptosporidium. Filters can remove both good and bad substances from your water. Depending on your circumstances, filtering your water might not be a good idea.
There are many different types of filters available, and it can be confusing to decide whether you need one or which kind is best for you. In many areas of the world, the water is not safe to drink, so filtration is one option to protect your health. Here are some steps to consider when determining whether you want to use a water filter, and if so, what type and functions best fit your specific needs and preferences.