How To Buy A Reverse Osmosis System

You would think buying a drinking water filter would have been an easy task where you went to the store, pointed at one on the shelf, then took it home and set it up.  Then you realize there are more filter types than the number of your fingers!  In this article, I’m going to show you how to buy a reverse osmosis system.

Whole House Filtration Or Only For Drinking & Cooking Water?

The first item you need to consider is if you want a point-of-entry whole house water filter that will filter all the water in your house or a point-of-use filter that will only filter the water at a specific location such as the kitchen sink.

If you want a whole house filter, you will need to set a spending limit.  A carbon whole house filter will cost around $700-800 while a whole house RO (Reverse Osmosis) will start around $2000 for a small system.

Obviously whole house filters are going to be more expensive than a point-of-use filter.  You can purchase a quality under sink (undercounter) RO unit for $200.  For most people who want reverse osmosis, this is the only feasible option.

How To Remove Fluoride In Drinking WaterItems To Consider With Whole House Reverse Osmosis

  • Electricity Required
    • This might not be a dealbreaker if you are already on a well and need electricity for the pump that delivers the water throughout your house.
    • Most carbon filters do not require electricity.
  • Space for 300+ gallon atmospheric storage tank required
    • You will need to set aside room in your basement, utility room, or garage for the atmospheric storage tank that holds the filtered water.  So you might need to carve out some extra space next to your water heater or water softener.
    • Additional space is also required for the actual filters and the variable speed pump that delivers the filtered water through the house.
  • Probably need to hire a plumber to install a whole house unit.
  • Consider a post-membrane filter.
    • Most whole house units will come with an Ultraviolet Light filter that will get rid of any bacteria or viruses that might have still remained or developed in the water after passing through the RO membrane or while in the storage tank.
    •  You might also want a pH alkaline filter that automatically introduces healthy minerals back into the filtered water.  One negative of RO is that healthy minerals are removed alongside unhealthy minerals as they are all Total Dissolved Solids.

Ideal Candidates For Whole House Reverse Osmosis

  • Households who drink well water with high amounts of bacteria or TDS (Total Dissolved Solids), including high amounts of sodium, nitrates, radioactive metals, or fluoride.
  • People on “city water” that want the purest quality of water available that also would want nitrates, radioactive metals, or fluoride removed from all their water.
    • Carbon whole house filters are great at removing chlorine, chloramines (using catalyzed carbon), volatile organic compounds, disinfection by-products, and metals BUT ineffective at removing fluoride.
  • Folks who have water sensitivities.  Reverse Osmosis offers the most peace of mind at the most cost-effective price.
  • Business owners who might run a coffee shop or restaurant that wants pure water.  Commercial-grade RO systems are available for businesses and households.

Undersink Reverse Osmosis

How To Buy A Reverse Osmosis Filter

Cutaway of the 5 stage APEC filter system

Onto the most affordable option, thus most popular choice, for reverse osmosis.  You can call it an undersink or undercounter filter.  For this article, we will call it an undersink unit.

There are several companies that make undersink units.  Like the standard SUV produced today, most of the units are very similar in appearance and there are small design differences in each brand.

When it comes to the undersink reverse osmosis, I recommend a system produced by either APECor iSpring as they produce units that are NSF certified and produced in the USA.  Their materials are better quality than other brands and are sold at a reasonable price.  Both brands have good user reviews and the systems are reliable and not prone to leaks.

Although this is just personal advice, most water filter sites will also recommend to avoid the typical reverse osmosis units sold in regular big box stores.  Most of them are mass-produced overseas and use inferior material.  This means after a couple years of use, you run the risk of having cracked seals that create water leaks or spend money for replacement parts or the entire system.  No brand is perfect (even the two I recommended) but as the old saying goes, “You get what you pay for.”

How To Remove Fluoride In Drinking WaterItems To Consider With Under Sink Reverse Osmosis:

  • No Electricity Required! *For most systems
  • Purchase a 5 stage system at the minimum.  Having two carbon pre-membrane filters will provide cleaner water and can also extend the lifespan of the reverse osmosis membrane.
  • Consider a 6th stage filter.
    • An additional post filter can be one that automatically puts healthy minerals back into the water.  It can be called an “alkaline filter” or “remineralization filter” depending on the brand.
  • Try to get a system with “quick-connect” fittings
    • These fittings make installation and filter replacement easier & quicker!
  • Space is required underneath the sink for the storage tank and filters.
    • Storage tank measurement dimensions are typically 11″ wide x 11″ deep x 15″ tall.  There can be minor variations depending on brand name and tank size.
    • Filters can be mounted on the cabinet wall and require approximately 16″ wide x 5.25″ deep x 17.5″ tall.
      • People also mount filters in adjacent room or on counter top.  You might need use additional tubing to connect the system.  Will also need to test water pressure to ensure it is above 40 PSI or will need to purchase a permeate pump.
  • Ideal water pressure is 60 psi, however most systems can effectively filter with PSI between 40-85.
    • PSI below 40 PSI will require either a non-electric or electric permeate pump.
  • If your water supply is disinfected with chloramines, you will need to use catalyzed carbon instead of the regular carbon block to effectively remove the chlorine and ammonia.
    • To upgrade the carbon filters, you may need to contact the manufacturer directly.  This is the case with APEC.
  • Most undersink systems do not require a plumber to install.
    • Most undersink systems advertise DIY install.  There are also Youtube videos available to help with installation.  You will need to read the directions carefully and it helps to have some experience as installation does require a time commitment of at least an hour or two.
    • If you are installing parts of your system in a location other than the underneath your sink, you may want to call a plumber to assist.

Ideal Candidates For Under Sink Reverse Osmosis:

  • People that want reverse osmosis on a budget
  • People who only want RO for specific purposes such as drinking, cooking, or fish aquariums.
  • People that have a carbon whole house filter but want reverse osmosis for cooking and drinking water.

How Many Gallons Per Day Do I Use?

Reverse osmosis units are rated by the number of gallons they can filter each day.  Reverse osmosis relies on water pressure and it is a slow pressure.  So a higher rating means that the system can filter a gallon of water quicker than a lower rated system.

Under Sink Units

Under sink units come in two common ratings: 45 gallons per day or 90 gallons per day (GPD).  You are probably thinking that is a lot of water and we do not consume that much. True.    The standard atmospheric storage tank will only hold 3 or 4 gallons of filtered water at one time.  When you get to the bottom of the tank, the water flow will reduce to a trickle.

A 45 GPD system can filter 1.5 gallons per hour and a 90 GPD system can filter approximately 3 gallons per hour.  A 45 gallon system is recommended for households of 6 or less people.  If you have more than 6 people or a high demand for filtered water, a 90 GPD system will be the better choice.  Remember that each brand might offer different filtering capacities, iSpring produces a 75 GPD system for example.

Whole House Units

The same principle applies for whole house units.  You are generally going to want your system to be rated for double the amount of water you use on a daily basis.

A entry-level whole house filter will be rated for approximately 400 to 500 gallons per day.  This is ideal if you use no more than 200 gallons per day.

Where To Buy Reverse Osmosis Filters

There are two different places to purchase reverse osmosis filters.  Directly from the manufacturer or Amazon.  Some units can only be purchases directly from the manufacturer, plus you might receive an increased level of customer support and product warranty if purchased from the manufacturer.

Whole House Filters

Raindance Water Systems

There aren’t that many manufacturers of whole house reverse osmosis filters.  I personally think they have the best whole house products available & great customer service.  Their products are made in the USA, which is a huge plus in quality & also for providing domestic jobs.

Raindance also sells under sink reverse osmosis units & a plethora of other filtration products for residential and commercial use.

Under Sink Reverse Osmosis

There are two names that provide quality filtration systems at an affordable price.

    1. APEC

APEC has been making water residential and commercial filters for over 17 years.  The systems are custom built and tested prior to shipment.  Their under sink units come in two different ratings: 50 gallons per day & 90 gallons per day.

There customer service has always been quick to respond when I have had a question.

2. iSpring

The iSpring RCC7 system is very similar to appearance to the APEC system but offers higher filtration capabilities at a slightly lower price.  iSpring’s 5-stage system is rated at 75 GPD and currently sells for $188.  APEC filters 50 GPD at $199.

There is conflicting information on the internet regarding the country of origin for iSprings products.  I contacted their customer service, who said the sediment pre-filters are made in Taiwan, but the carbon filters and RO membranes are made in the USA.  The systems are also built and assembled in the USA.

If your water pressure is below 45 psi, you will need to order an appropriate booster pump.

One nifty feature I like, is their fitlers have clear housing so you have an easier time of seeing when that particular filter is due for replacement.

One downside to the iSpring when compared to APEC is that the carbon filters will need replaced every 6 months, as opposed to APEC’s recommended replacement interval of 12 months, however the replacement filters for both companies are very similar in price (APEC is still a little more expensive).  A year supply of the sediment and carbon filters currently costs $38.99.

iSpring sells their products through Amazon:

The filter above is their entry-level 5-stage system will filter 75 gallons per day.

Pictured below is iSpring’s 6-stage filter that includes an “alkaline” post-filter that will put healthy nutrients back into the water for you.

Final Step: Enjoying Pure Water

Finally the last step is to enjoy this great tasting water from whichever filter you choose.  With reverse osmosis you have peace of mind that your water has up to 98% of most contaminants removed from it.

Please enjoy a glass of good tasting water for me!

What reverse osmosis filter are you considering?  Have you used reverse osmosis in the past?




  1. I used to sell water filters in the 80’s through a MLM company. These are very good affordable systems and you’ve provided a great review. Thanks for this.

    • Thanks. Water filter technology has come a long way in a few short decades. Ideally, we wanted a whole house reverse osmosis but simply cannot afford it. So we are doing an undersink RO for drinking & cooking, then installing filtered shower heads to address our bathing. We will be on chlorinated water with our new house, so we are trying to limit our exposure as much as possible.

Leave a Reply

Your email address will not be published. Required fields are marked *