This post describes the different options with home water filters. There are advantages and disadvantages to the various residential water filter options. The two basic categories are whole house filters and “point of use” filters. Even though the water coming into your home is tested constantly for safety by your municipality, sometimes the taste is not as pleasant as some people would like. This can be especially true in the city of Minneapolis during the summer months. The reason is that Minneapolis draws it’s water from the river and the relative flow rate and dissolved materials percentage increases in the dry summer months when the flow rate is relatively low. Some people want to use water that is cleaner than that provided by the municipality. Surrounding suburbs; Edina (wells, high iron content), St. Louis Park, etc. have a entirely different set of circumstances and water content issues and as such I would recommend you; do your own research, talk to the municipality, engage more than one water quality company/expert and sift all of the above for what you believe is the best solution for you.

There are different options:

A whole-house water filter

The drawbacks

I do not usually recommend these because they are relatively expensive to install and especially to maintain. There are some people who have sensitive skin or other valid health concerns where a whole house filter is necessary. One of the negative aspects of a whole house units filter that many times the piping of the house requires filtering of water used for non-drinking purposes such as; toilets, showers and watering the lawn. The filters need to be changed often and they are expensive. Almost without exception, when I have visited a home where there is a whole house filter it is no longer in use.

Reverse osmosis (“RO”) filters

These filters create water purity close to distilled water by using pressure to pass the water through a membrane, which separates impurities from the water. Unfortunately there are several disadvantages to this process:

  • There are beneficial minerals and other dissolved materials in the water supply (i.e. flouride, calcium, iron, etc.). Eliminating these minerals from your body by drinking water this pure can actually CREATE medical problems. The medical problems appear to occur only with excessive consumption, but this does provide food for thought. (See Wikipedia Distilled water.
  • The cost in terms of equipment, installation, and space are significantly greater than for a canister type filter.
  • These are very inefficient in terms of water use. Approximately 8-18 gallons of water (!!) are sent down the drain for every gallon produced (Wikipedia). This is largely an emotional or environmental consideration rather than economic as our cost of water is so incredibly inexpensive.
  • It can be expensive to connect these systems in a way that meets plumbing code. I have seen many installed by (?) that were not done to code because it was cheaper. One problem I’ve seen is the way the discharge water line was directly connected to the waste piping under the kitchen sink (not to code, aka illegal). A second problem category is the way the water supply is taken from the existing piping and connected to the new R.O. system. Not to code makes the install quicker and cheaper and can be done by non-licensed person as the shortcuts they use don’t modify the existing piping. Minor issue: These shortcuts do present greater probability of leaks due to the design of the fittings used. As such A plumber would likely need to make corrections to these types of installations when subsequent  work (a new faucet, replace shutoffs, replace dishwasher, etc.) is required at the kitchen sink.
  • On-going maintenance is critical. R.O. water is created by the water passing through a “membrane”. The effectiveness is dependent on membrane integrity. To protect the membrane there are pre-filters that need to be changed regularly or the membrane can rupture. The hardest thing for most people is to remember to do routine maintenance. If the membrane ruptures, you’ll probably never know that you are just drinking filtered water, not RO water.

Point-of-use filters

There are two main types:

(1) Filters that attach to the faucet outlet in place of the aerator


  • Least expensive in cost and installation (many times the homeowner can do this with few or no tools).
  • If you are concerned about water from your shower, an inexpensive filter can be installed right at the shower head (many times you can do this with few or no tools).


  • May not filter water from a kitchen faucet as well as an under the counter filter.
  • Cannot be installed on many newer kitchen faucets (e.g. those with a pull out spray head)
  • Lower useful life before needing to replace or maintain.
  • The filters you attach to the spout have limited capacity in terms of total gallons and materials contaminants removed. To get the best of both of these you need an extra faucet installed at the sink that dispenses only treated water. The reason is that a canister type filter has a limited flow rate that would be unacceptable for washing dishes, etc.

(2) Filter and housing mount under the sink with a separate faucet at the kitchen sink

This is generally referred to as a filter for “taste and odor”. It is comprised of activated carbon ( I recommend a 0.5 micron filter.


100% water efficiency. “An R.O. unit delivering 5 gallons of treated water per day may discharge 40 to 90 gallons of waste water per day” (Wikipedia: Reverse Osmosis).

  • It filters only the water you want for (e.g. cooking and drinking)
  • It filters out a healthy amount (ba-dump-bump) of  the harmful stuff (biological, chemical) and leaves in the good stuff (minerals, fluoride, iron, etc.)
  • It is less expensive to install and maintain than RO because of lower use, less complexity.
  • These filters take up fare less space under the counter than RO filters. Hangs on the cabinet side wall, takes up about 5 inches X 5 inches of “floor” space.
  • The cartridge can last 12 months (capacity 1000 gallons).
  • You can change the cartridge yourself.
  • Cartridges are very inexpensive and can be ordered on-line.
  • This has an unlimited amount of water at any given moment. Such as cooking food in water, making beverages, all at the same moment. A refillable pitchers (which will produce similar quality of water) maybe a gallon (?) and takes up space on your counter or in the fridge. And you have to refill it every time.
  • Here’s a before and after conversion. The faucet pictured is the same model as I’ve had in my home for about 20 years and still working fine.


  • This requires a separate hole in your sink for a dedicated faucet just for filtered water. This is required because the flow rate to achieve good filtration is much lower than that required for your primary faucet. If you have an existing sink/counter top (you are not considering remodeling) usually all the holes are occupied. To make a hole available for the filtered water faucet usually involves the replacement of your existing kitchen faucet.
  • A detailed reading of water quality will reveal that there are many organic and inorganic materials that are dissolved in the water supply in trace amounts.  This type of filter will not remove them. These are a such a low level that current testing and scientific studies are unable to show a direct link to adverse health effects. The vast majority of people are unconcerned about this. Most relevantly, in my opinion, eliminating these at the municipal level would be so inordinately expensive that it cannot be justified. I believe that is why existing health guidelines and regulations are what they are. If you are very concerned about this level of detail, that is beyond the scope of my expertise.