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Do you know what’s in your drinking water? Don’t buy into the myth that bottled water is safer than tap water.  The US enjoys some of the cleanest and clearest water in the world. Yet, there are times when you might want to consider a home drinking water filter system. 

Just because the water is safe doesn’t mean you’ll like the taste. Home  water filtration also makes sense if you have hard water or well water, notice rust on your plumbing fixtures, or think you have scale buildup in your pipes. 

Some home water filter systems work only at the point of use. That is, you may have a filter in the kitchen for drinking water. It won’t affect the water you use anywhere else. Other filter systems work at the point of entry. That is, they serve as whole house water filters. Most people probably don’t need whole house filtration systems

Different kinds of filters work on different kinds of impurities. It’s not like you can just go out and buy a water filtration system. You need to know what impurities you want to filter. Minerals? Germs? No one filtration technology works on everything. 

Some thoughts on water quality

Water faucet. drinking water filter system
Photo by Steve Johnson from Pexels

If you are on a public water system, it provides a water quality report every year. It lists all the contaminants and regulated toxins utility tests found in the water over the previous year. 

The report tells you where your drinking water comes from. It could be a river, a lake (natural or manmade), an underground aquifer, or some combination. The report also summarizes the source water assessment the state provides and EPA standards for drinking water contaminants. These standards come from the Safe Drinking Water Act of 1974.

A chart that lists levels of all detected contaminants takes up most of the report’s space. Hopefully, it shows that all the levels of contaminants are below the EPA’s maximum allowable limit. If not, it will identify possible health effects. In case of a violation, you should have already heard about it when it occurred.

Do not drink water that does not meet EPA standards. 

Thanks to the Safe Drinking Water Act, the US leads most of the world in clean drinking water. More than 90% of all water utilities meet EPA standards. 

But you may still want to filter your drinking water. Why? 

  • Your local system might not consistently be in the 90%.
  • You might prefer the taste of filtered water.
  • You might have health concerns about specific substances that perhaps most people wouldn’t have.
  • Your house might have very old plumbing that still has lead pipes or pipes with lead solder. 

The first step in choosing a drinking water filter system is to decide what you want to filter out. Any filter will work well at filtering out some specific contaminants but not others. Here are the choices:

Point of use drinking water filter systems

Particulate matter filters

Particulate matter, or mechanical drinking water filters only filter out large particles. They usually act as a prefilter along with some other technology.

Adsorption filters

water filtering pitcher

Photo by Patrick Haney via Flickr

Adsorption means that certain particles stick to filter material. These drinking water filters work very well at removing chlorine, chlorine byproducts, and volatile organic compounds. They also successfully improve taste. 

When most people think of drinking water filters, they probably have activated charcoal filters in mind. They are the least expensive and most common filters on the market. They do not, however, remove minerals or inorganic compounds.

Handy and convenient water filtering pitchers are the most common drinking water filter system. You simply put water in the top compartment and let it go through the filter. It does take some time to work, however. 

You’ll need to replace these filters every few months. Some brands of pitchers, at least, provide stickers to help you keep track of when you need a new filter. 

You can also get end of faucet filters, countertop filters, and under-sink filters with replaceable activated carbon filters. The countertop filters allow you to run filtered or unfiltered water through the same faucet by turning a diverter valve on or off. If your refrigerator provides drinking water, it has an activated charcoal adsorption filter.

Activated alumina filters more effectively take out fluoride, arsenic, and selenium. Most water systems add fluorine to prevent dental cavities, but sometimes naturally occurring mineral waters have fluorine levels above the legal maximum. In those cases, the water utility will have already used activated alumina to bring it down. I personally don’t understand why anyone would want to filter out fluorine unless they distrust the recommendations of organized dentistry. 

Another adsorption drinking water filter uses ceramics. Unlike activated carbon filters, they last for years. Instead of replacing them periodically, owners must clean them. But also unlike activated charcoal, they can break. They are primarily recommended for reducing germs in the water, although they have little effect on viruses. 

Reverse osmosis

reverse osmosis home drinking water filter system
Reverse osmosis home system. Wikimedia Commons

Reverse osmosis forces water through a membrane. Anything larger than a water molecule cannot pass through the membrane. It removes every kind of contaminant except germs. In fact, it is the technology used to desalinate ocean water. 

If you get your water from a water system, it should already be sufficiently germ-free. If you need a system to kill germs, use ultraviolet light. That said, reverse osmosis is a very good home drinking water filter system. The water is always ready and components don’t need to be replaced as frequently as activated charcoal filters.

The reverse osmosis process is expensive and inefficient but very thorough. It puts water through at least three filtration cycles. It starts with a particulate matter prefilter to remove the largest particles. Then, in some order, the water passes through a carbon filter and the reverse osmosis membrane. 

Water exits the reverse osmosis system in two different streams. Filtered fresh water, called permeate, goes into a storage tank. Water with all the rejected materials, called brine, goes down the drain. The system produces three or four gallons of brine for every gallon of permeate. 

With all these different filtration processes, reverse osmosis systems work very slowly. If you wanted to get a glass of water at the rate the system works, it would take five minutes. Therefore, the permeate goes into a storage tank. When the tank is full, the system shuts off. At times when a lot of people want to drink water, they can empty the tank, and it takes a long time to refill it.

Reverse osmosis is not suitable as a whole-house treatment. Since it’s a point-of-use system, reverse osmosis only produces brine at faucet(s) with the filters. So it doesn’t quadruple your water usage. It will increase it noticeably, however. 

Most commonly, the machinery sits under the kitchen sink. You can also hook one up to your refrigerator to provide filtered water and clearer ice. If you want, you can put systems in bathroom sinks, too.

Distillation

Distillation systems boil water. Technically, then, they are not drinking water filter systems. 

When the steam cools, it becomes liquid water again. The process leaves minerals behind and kills germs. Heating the water requires more energy than other water treatment methods. 

Basically, distillation leaves behind anything not capable of becoming a gas at the boiling temperature of water. That includes, of course, all the minerals that give water a pleasant taste. It does not include volatile organic compounds, which become gases at lower temperatures. Distillers therefore require a separate process to remove them.

Point of entry whole house water filtration systems

Water softeners

If your area has hard water, many homes will have a water softener that treats water at the point where it enters the house. In other words, it is a whole-house water filter, or part of one. It treats not only drinking water, but all the water used for bathing, laundry, cleaning, and whatever you do with outdoor spigots.

Water softeners use a process called ion exchange to take out hard metal ions and add sodium or potassium ions in their place. Hard water leaves mineral deposits behind in pipes and on surfaces. Soft water does not. 

Owners of water softeners must periodically fill it with salt pellets. That can cause problems for people who must restrict their intake of sodium. It can also harm houseplants. Using a potassium salt instead of sodium salt can be a better choice in these cases. 

Ultraviolet treatment

ultraviolet light LEDs. drinking water filter systems
Ultraviolet LEDs. Wikimedia Commons

Ultraviolet light water purification isn’t technically a filtration method. Used on already filtered water, it kills germs and viruses. It disinfects without chemicals and without changing the taste of the water. 

If you have an ultraviolet system and some kind of natural disaster requires your water system to issue a boil water advisory, you don’t need to heed it. The system has already killed all the germs in the water before it gets to your faucets. 

On the other hand, if you use well water, you must disinfect the water before you can use it. Your only choices are ultraviolet light and chemicals. 

In either case, maintenance of an ultraviolet purification system is simple: replace the bulb once a year and the quartz sleeve every two years. Clean the sleeve occasionally. Keep an extra one handy, though. They’re fragile. 

If used with a water softener, the water goes through the softener before it gets to the UV system. Operation of the UV light bulb requires electricity, so it won’t work in a power outage. And it will heat the water that sits in the tank. 

You can also get a handheld UV water purifier if you enjoy camping or traveling to parts of the world with inadequate water treatment. 

Sources:

Common types of water filters and how they work / Healthy Kitchen 101. September 16, 2020
Guide to safe tap water and water filters / Food & Water Watch
Which is the right type of water filter for you? / Donna Boyle Schwartz, Bob Vila.com. 

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