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6 Common Mistakes People Make When Shopping for a Whole House Reverse Osmosis System

by Mark Timmons May 18, 2020 2 Comments

It may be somewhat surprising to some that whole house reverse osmosis systems are even a “thing” but the reality is many consumers are now aware of the magnitude of water problems and realize that reverse osmosis removes the largest spectrum of contaminants of any water treatment technology. We have been at the forefront of this technology for many years and likely sell more whole house reverse osmosis systems than anyone.

In our years of experience, we have learned many things the hard way. To borrow a saying: “We know a thing or two, because we have seen a thing or two.” We have built and installed thousands of whole house reverse osmosis systems, and over the years, we made a lot of mistakes… which we learned the hard way. We still see consumers making the same mistakes we did ten or twenty years ago, so we thought we would share our experience to save you from making mistakes that you may not know about. In the long run, doing it the right way will save

Top 6 Most Common Mistakes

#1 - Failing to Use a True Commercial-Grade Pump

Look, for those of you who don't know me, you need to understand that I have no problem calling out people or companies who are doing things or saying things that have little basis in fact. I believe in calling things the way I see them and explaining why. A whole house reverse osmosis should include a true commercial-grade booster pump, and frankly, most of the “alleged” commercial RO systems you see on the Web or anywhere DO NOT have a commercial-grade pump. “But this is a residential whole house reverse osmosis system - why do I need a commercial-grade pump?”

That's a valid question, but the short answer is that in many respects, a whole house reverse osmosis system works just like a commercial system. After all, it supplies all of the water you use in your home. When it quits working, you have no water! We learned a long time ago that you had better use a true commercial-grade pump, or you may replace it a couple of times a year.

There are three (3) basic types of pumps used for reverse osmosis systems. Only one is a true heavy-duty commercial-grade pump, and that is a Multi-Stage Centrifugal pump. However, we frequently see companies use diaphragm pumps and rotary vane pumps on systems that they “say” are commercial grade. Rotary vane pumps are certainly preferable to a diaphragm pump, but it really is not commercial grade. Comparing a rotary vane pump to a multi-stage centrifugal pump is like comparing a Smart Car to a 1-ton pickup truck. There is simply nothing to compare. If your whole house reverse osmosis system does not include a multi-stage centrifugal pump, you are likely doomed to replace the pump quite frequently. My advice is to do it right the first time.

A True Heavy Duty Pump For Commercial Grade Applications

Diaphram Pump

Light duty pump for intermittent applications. Commonly used for under-sink RO applications.

Rotary Van Pump

Standard pump for residential RO applications where continuous operation is not needed.

Multi -Stage Centrifugal Pump

Heavy duty commercial grade pump engineered for continuous operation over a long period of time.

#2 - Failing to Use Proper Pretreatment

A whole house reverse osmosis system does a fantastic job of removing just about anything in the water, but a reverse osmosis system is not engineered to remove the following contaminants from the water:

  • Hardness is composed of calcium and magnesium which causes scale on the membrane surface, greatly effecting producing and water quality. It is advisable that a whole house RO system either have a water softener or and anti-scalant system ahead of it. We generally recommend the anti-scalant system because a 32 ounce bottle of Hyper-Guard Plus 7000 weighs a lot less than a bag of salt and one bottle of Hyper-Guard Plus 7000 will usually treat more water than 20 bags of salt. Unless you think lifting salt bags is an Olympic Sport, we recommend sticking with the anti-scalant. By the water, the anti-scalant is NSF and FDA approved but is rejected by the RO membranes so it is not in the water supply. A bottle of the Hyper-Guard Plus 7000 is mixed with RO water, and, in many cases, it lasts 3-6 months.
  • Iron or “rust,” as it is often called, literally plugs the membranes and does it with a quickness. The Hyper-Guard Plus is effective at removing low levels of iron, but I always recommend removing it with an iron filter of some sort. It is much more sustainable and economical in the long run. What method you use for removing iron depends upon the levels, the type, and whether it is bacterial.
  • Manganese is as troublesome as iron in many cases. And one of the most effective ways to remove it is with a water softener. Again, it depends upon the level and what other competing contaminants there may be in that particular water supply.
  • Chlorine is detrimental to any thin-film membrane and should always be removed ahead of it. Cartridges are not recommended because they have a very limited life. It is always a best practice to use a tank of carbon and if anything, oversizing it.
  • Chloramine is formed by adding ammonia to chlorine and is even more difficult to remove than chlorine. It requires a special type of carbon, called catalytic carbon, to effectively remove it. Our BodyGuard Plus system has a blend of both types of carbon to effectively remove both chlorine and chloramine.
  • Turbidity is caused by visible solids in the water and needs to be removed through a backwashing sediment filter, step-down filtration, or a spin-down filter. In some rare instances, you may have to use all three.
  • Hydrogen Sulfide or rotten-egg odor can pass right through a RO membrane and also foul the membrane in the process. In my opinion, hydrogen peroxide is the best method to remove practically any level of H2S.
  • Bacteria is something that needs to be eliminated BEFORE the reverse osmosis system. No RO system should be installed on water that is not microbiologically safe unless the bacteria has been neutralized first by whatever method is deemed effective, such as ultraviolet disinfection or chlorination.

The worst whole house reverse osmosis system will operate much longer with proper pretreatment, and a great whole house RO system will operate for 20+ years with proper pretreatment. If anything, oversize the system to increase contact time as “prolonged contact” is paramount to proper pretreatment. This is an area where many consumers mistakenly try and cut corners.

#3 - Failing to Size the RO System Properly

OK, now I am getting really fired up! Reverse osmosis systems are rated at peak capacity and are tested at 60 psi and a 77 degrees F water temperature. The problem is that in most areas, the water temperature is in the 50s. Look, I did not invent the way they test RO systems, I am just reporting to you how they do it. All RO systems are rated with those standards.

The fact of the matter is that if you have a 500 gallon per day (gpd) RO system and your water temperature is 52 degrees, you really have a 250 gpd RO system. Here's why: for every degree below 77 degrees, you lose approximately 2% efficiency. Do the math: 77 - 52 = 25 x 2% = 50%. In the real world, you will get about 250 gallons out of the machine you thought would deliver 500 gallons… and that is if it runs 24 hours a day!

Energy-wise and longevity wise, running a reverse osmosis system 24 hours a day is a recipe for disaster. I like to see a RO system run 6-8 hours a day - AT THE MOST! If it runs less, it simply increases the life of the system and cuts down on energy. That is why our whole house RO systems start at 2,000 gallons per day. Remember, in the real world, that 2,000 gpd system may be 1,000 gpd and if you need, let's say 300 gallons a day, it will have to run about 8 hours to produce that.

If I were sizing a whole house RO system for a family that needed 300 gallons per day, I would use a 4,000 gpd system because it would only have to run about 4 hours a day and it would last just about forever. Centrifugal pumps last a long, long time when size properly and a properly sized system will work effortlessly and continuously for a long, long time. Our systems have double the warranty of most other systems and know you know part of the reason why.

#4 - Failing to Consider the Doorway Opening for the Tank

It sounds simple, but anyone can see that a 35” tank will not fit through a 32” door opening. No way, no how! Measure twice and be certain the tank will fit into your home. While we are talking about tanks, let me give you my opinion. Some companies undersize the RO and oversize the tank. I would rather oversize the RO and downside the tank. Why take up more space than you need to?

We typically use a 140-gallon atmospheric tank for a whole house RO system. It fits through any door and if you need additional storage, you can manifold 2 or 3 together. However, I prefer to just upsize the RO so that it makes water faster, and then a bigger tank is not needed. Here's how many gpm each RO makes at peak flow:

  • 2,000 gpd - 1.38 gpm
  • 4,000 gpd - 2.77 gpm
  • 6,000 gpd - 4.16 gpm
  • 8,000 gpd - 5.55 gpm
  • 12,000 gpd - 8.33 gpm
  • 16,000 gpd - 11.1 gpm

So, you start out with 140 gallons in the morning and if you have a 4,000 gpd RO, you can produce about 206 gallons of water the first hour. However, if you had a 8,000 gpd RO you could produce 473 gallons the first hour. So, it depends upon what your demand might be.

#5 - Failing to Consider How Much Water is Wasted

It used to be that reverse osmosis systems wasted up to 6 gallons for every gallon they make. Over the years, as membrane technology and efficiency has improved, we are now at a point where we can produce 4 gallons of water for every gallon wasted. Most of our whole-house RO systems are 75 to 80% efficient. Some competitors say they are 50% efficient, and even if they were, that means that they will be dramatically less efficient than ours.

This is a big deal! If you are no city water, you must pay for that water, so the cheaper system that is 50% efficient ay actually cost you more in your water bill. Consider the cost, instead of price. That brings me to #6.

#6 - Buying a System Based Upon Price Only

Of course, you don't want to overpay for anything, but price is relative. Frequently, you get what you pay for. For instance, we use stainless steel needle valves, stainless steel fittings and stainless-steel reinforced Schedule 80 PVC fittings. We also use stainless steel membrane housings and American made electronics, pumps and solenoids. These all cost a lot more… but the quality is vastly superior. Many of the systems on the market are Made in China or Taiwan… not made in the USA. Most of the material in our whole house commercial RO systems are sourced in the USA, but it's impossible for every little item to be USA Made. We strive every day to rely less on foreign suppliers and are very close to being 100% American Made.

I can confidently say that you can find lower-priced Whole House RO systems than ours, but I don't think you can find any that come close to our cost! A lower priced system will likely COST a lot more over the life of the system.

There you have it my friends. Choose wisely!

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June 10, 2020 Sam


I finally installing a Defender Model 224-DFWHRO in my home and I’m working with a professional plumbing company on installation. I created a diagram for the system and was hoping you could do a quick review. My goal is to do it right the first time. Is there anyway to contact you?

June 15, 2020 Mark Timmons

Just reach out to Technical Support and they will direct you.

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