At US Water Systems, we constantly deal with people daily, including homeowners and business people looking for a commercial reverse osmosis system or a whole house reverse osmosis system. The truth is that a whole-house Reverse Osmosis (RO) System is a commercial-grade system. They are the same because a whole house RO system has to be commercial-grade for it to last.

I recently talked to a gentleman who worked for a company that needed reverse osmosis water and deionization (DI) polishing. Deionization delivers water that is exceptionally high in purity, and generally, many businesses need water quality which is what is called Type 2 DI water. That means that it is a minimum of 1.0 meg ohm.

Many companies make deionized water through what are called DI exchange tanks. However, this is not very economical because starting with tap water and turning it into DI water can cost more than $0.50 per gallon. However, if you utilize reverse osmosis ahead of DI, the cost can drop to $0.02 to $0.05 per gallon. It is smarter to have a reverse osmosis system ahead of deionization. RO is the primary demineralization method and DI is the “polishing.”

In the case I am talking about, the gentleman was evidently in charge of procuring a Reverse Osmosis System followed by a DI system to deliver the high-purity water. He believed he needed 300 to 400 gallons of high-purity water a day. At $0.50 a gallon, Portable Exchange DI tanks were out of the question, so he was seeking a reverse osmosis system ahead of the DI cartridges. He looked at our Raptor Laboratory Water System, which makes up to 118 liters of water per hour or 31 gallons and he seemingly found it efficient. However, he didn’t know what he didn’t know.

U.S Water's Raptor Reverse Osmosis System

While the Raptor reverse osmosis system is rated to produce up to 750 gallons of water a day, realistically, you would not want to use it regularly. I’ll explain why. The Raptor RO/DI System is pictured (the tank is not pictured as multiple sizes are available). In this case, the gentleman above believed that a 120-gallon bladder tank was the best bet and that he could add a second tank so that they would have about 240 gallons of DI water available.

The problem is that a 120-gallon bladder tank will not hold 120 gallons of water because it has an air bladder. A 120-gallon pressure tank has a drawdown volume of only 36 gallons, the amount of usable water it can hold. Bladder-type pressure tanks are only about one-third full of water, with the remaining space filled with air. A pressure tank properly filled with air, will sound hollow when you knock on it. So, in reality, a 120-gallon tank will hold about 36 gallons of water.

Another issue is that the back pressure from the bladder will impact the DI water quality, driving the cost per gallon much higher. A reverse osmosis system will produce dramatically better water quality when you have an atmospheric tank. An atmospheric tank has no bladder, which means no back pressure on the membranes, so a pump is required to pressurize the water. It also generally has an electronic float which shuts off the RO system when the tank is full.

Another issue is that all reverse osmosis systems are rated at a certain gallon per day capacity (GPD) at 77 degrees F. For every degree below 77 degrees F, you lose approximately 2 percent capacity. If you are in a cold climate you can impact your production by up to 50%. In other words, a 750 GPD RO system might be 375 GPD, but understand that it will have to run 24/7 to do that! Of course, if an RO system runs that much, you better keep three or four pumps on hand and learn how to replace them, because you may have to replace them every few weeks.

Types of RO System Pumps 

There are three types of pumps used in RO systems. Our Raptor and Maverick are considered “light commercial systems” because they use a Diaphragm Pump. The membranes will make up to 750 GPD, but if you need more than 100 GPD constantly, you would not want to use a Diaphragm Pump. To the left is a picture of a Maverick with a Diaphragm Pump. Please be aware that these “light Commercial” RO systems should not be used continuously for heavy duty. I have a 750 GPD Maverick in my house that feeds a couple of sinks, icemakers, and a humidifier. That’s where a Maverick or Raptor shines. The longer a motor runs each day, the shorter the life!

Several variables determine how much water a reverse osmosis system produces daily, including TDS, line pressure, water temperature, and whether a bladder or atmospheric tank is used. If you plan on using a few hundred gallons of water daily, consider using the Liberty or the Defender System. The Liberty comes in several sizes from 500 GPD to 2,000 GPD. It also uses a stainless steel “Rotary Vane” pump superior to a Diaphragm Pump. 

However, while a rotary vane pump is superior to a diaphragm pump, it is not considered a heavy-duty system that will work “day in and day out.” That’s why we do not recommend using a rotary vane pump for whole-house applications or anything but “moderate duty” commercial applications. It is not made to stand up to the rigors of heavy daily operations.

As a rule of thumb, you may use a Raptor or Maverick if you use a few dozen gallons of water a day and occasionally use a hundred or so gallons a day, if you need a hundred gallons of water a day or occasionally more, then you should consider getting a real commercial grade reverse osmosis system with a stainless steel multistage centrifugal pump. Properly applied, these pumps can last 20 years or more.

The Defender Reverse Osmosis System uses a stainless steel multistage centrifugal pump and while we make a 2000 GPD, a system with multiple membranes will produce the highest quality water. Depending upon how much water you need daily, you would need a 4000, 6000, 8000, 12000, or 1600 GPD system. A multi-membrane system will produce less TDS water than a single-membrane system, reducing DI costs. A Defender Reverse Osmosis System might look like this one with the RO Model (4000 GPD pictured) with Anti-Scalant and Granular Activated Carbon Pre-Treatment, and the storage tank and Ultraviolet disinfection.

DI System Configurations

We offer several configurations for the DI part of the system, using DI cartridges (typically 4.5” x 20” diameter with 222 double O-ring positive seals. We also provide, quality lights, recirculating options, and Digital Monitors and Controllers for Resistivity measurement.  

The defender RO is built with one goal in mind: “This system needs to be of the highest quality in the industry, built better than it needs to be so that it will work better and last longer than any other system.” With stainless steel centrifugal pumps, stainless steel reinforced Schedule 80 threaded fittings, powder-coated (American Steel) frames, Asco Solenoids, stainless steel membrane housings, high-tech controllers, stainless steel gauges, and UV, the Defender is by far, the best commercial RO in the business. Some customers have told us that we “made it too good.” Actually, you will appreciate the quality forever!

Let us design a RO/DI system for you and if you need hundreds or thousands of gallons a day, we also have that covered with Electrodeionization Technology or EDI. EDI uses no chemicals, generates no hazardous waste, and makes ultrapure water continuously. This makes it extremely economical to have deionized water for the lowest possible cost. However, that is a blog for another day.