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By: Tyler Gatewood on June 9th, 2020

Microfiltration vs Reverse Osmosis: What Water Purification System Should I Use?

If you are shopping around trying to figure out the best way for you and your family or your office to have reliably clean drinking water, you are more than likely going to have a few basic questions: 

  • What are the different types of water purification systems available? 
  • What is the difference between Microfiltration and Reverse Osmosis? 
  • Which one is better? 
  • What is the difference in cost? 
  • Which system is best for my home or office?

At Exell, we want to provide you with the most accurate and current information available when it comes to decisions that affect those close to you. 

To that end, this article will examine the two types of water filtration systems we offer – microfiltration and reverse osmosis (RO) – examine how each system works, how effective each system is in removing contaminants, what requirements each system demands for installation, and other information you may want to consider when evaluating which system is right for you.

What’s Wrong with Tap Water?

When you turn on the faucet at your house, the water that flows out has arrived by a couple of basic means. If you live in a rural environment, you are likely receiving your water from a deep well that reaches through the soil into the groundwater. This water has seeped from the surface through soil, sand, and rock and reached a saturated zone called the water table. 

This water collects in spaces underground called aquifers, and can be pumped out of the earth and delivered into your home through a well system. The water is filtered by the soil and sand it seeps through on its way to collecting into aquifers. 

If you live in a more urban environment, you are likely on a municipal water system that gets water from wells and reservoirs, treats the water through chemical and physical processes, and is then delivered through the city’s infrastructure and your home’s plumbing system. 

Both systems leave you vulnerable to various types of contamination ranging from bacteria and pathogens to chemical hazards such as chlorine and lead contamination.

Whether driven by microfiltration or RO, adding a purification system to your home or office will result in consistently cleaner and healthier drinking water.

But what exactly do those terms mean?

Microfiltration and Reverse Osmosis Defined

Microfiltration works through a very straightforward process. Water passes through a filter with microscopic, pore-sized holes in it. Those holes allow the water to pass through but exclude particles and partially dissolved solids suspended in the water. Whether these solids are organic or inorganic in nature, if the contaminants are larger than the holes in the filter, microfiltration systems will exclude them from the water that passes through the filter.

Osmosis is different in that it is a process of diffusion whereby molecules pass through a membrane from an area of lower concentration to an area of higher concentration.

Think about taking a raisin in a dish of water and letting it remain there for several hours or a day. Naturally, the raisin would absorb water and swell. This is osmosis: movement from an area of low concentration (the water) across the membrane (the skin of the raisin) to an area of higher concentration (the raisin).  

Reverse osmosis, it would follow, is the process of osmosis but in the opposite direction.

In reverse osmosis, the diffusion happens across a membrane from an area of high concentration to an area of low concentration. In this case, water with a higher concentration of contaminants and other dissolved solids diffuses across a semipermeable membrane to an area with less contaminants and dissolved solids. 

Whereas osmosis is a natural process where the movement is spurred on by physics, RO systems introduce external force to push the diffusion across the membrane.

Microfiltration vs. Reverse Osmosis Which Results in the Purest Water?

Strictly speaking, microfiltration is a process by which water passes through a microporous membrane using pressure or leveraging only the force of gravity as a means of removing contaminants, such as dissolved solids or microorganisms. 

Since the process relies on a variety of filters, the end result of microfiltration can vary more widely than the product of reverse osmosis. Microfiltration can only filter out the contaminants that are larger than the holes in the filter.

Reverse osmosis, on the other hand, will result in nearly pure water since it relies on a physical process of diffusion that is not possible for the contaminants to achieve.

Lead particles will pass through a hole if the hole is large enough. Lead particles cannot become molecules in order to pass through a membrane because lead is not capable of osmosis.

It follows that RO systems will result in the purest water as a final product.

Case closed, right? Well, there are a few other considerations.

Requirements for Microfiltration Systems vs. RO Systems

While both systems require a water source with some degree of pressure, RO systems require a constant level of pressure typically above 50psi in order to operate. 

RO systems purify at a much slower pace than microfiltration systems. So slowly, in fact, that they often need to collect water into a storage tank that sends water to a dedicated faucet. 

Reverse osmosis systems require connection to a drain line as well, since they separate tap water into two streams – one of which is a wastewater stream and must be flushed out of the house through the connection to the drainage system.

Microfiltration units, on the other hand, do not create wastewater and therefore do not require access to drainage. This difference between the two systems highlights another disadvantage of RO systems – they require a higher amount of water than microfiltration systems. 

This means RO systems are less environmentally friendly than microfiltration units, and they will result in a higher water bill than microfiltration systems.

Which System Is Healthier?

While there is some uninformed chatter suggesting that water produced through reverse osmosis is unhealthy, this is a misunderstanding. 

The water that results from reverse osmosis is nearly contaminant free. However, some of those “contaminants” removed are minerals such as calcium and magnesium that are requirements for human health. 

Microfiltration systems can result in water that has more contaminants present, but those contaminants include some of the minerals that humans need to be healthy.

What About Cost?

When it comes to cost, reverse osmosis systems tend to be more complex overall. The units cost more than microfiltration systems and therefore tend to run about ten dollars more a month to rent. As mentioned above, they also create more waste through the course of operation and can result in higher water bills.

That being said, “cost” is not always the same as “price.”

While both microfiltration and reverse osmosis systems result in far cleaner water than tap water, there are some contaminants that reverse osmosis systems will remove for certain that can cause great harm to you and your family. 

Both systems will remove pharmaceuticals, protozoa and lead contamination, for example, but only reverse osmosis will remove certain carcinogens like nitrates, chlorine, and arsenic.

And the Winner Is…

Like most questions in life, the answer as to which system is better is…subjective. It depends on the variables that are the most important to you. Hopefully, this article will help you in your efforts to answer the question of which system is right for you.

Ultimately, whether you choose microfiltration or reverse osmosis, you should rest easy in the fact that your family members or coworkers will have drinking water that tastes better and is far cleaner than what they might get if they fill up straight from the tap.

The environmental impact of either system is substantially less than keeping scores of individual bottles of water supplied. And less, even, than the resources required by the delivery of 5-gallon bottles.

If you want help from an expert in deciding which system would best suit your needs, a member of our service team would be happy to survey your property, test your current water supply and discuss the range of options available.