What Is A Micron Rating? And Why Is It Important?

The micron rating of your water filtration system has a significant impact on how effective the system is. For this reason, it is vital to understand micron ratings before selecting water filtration for your home. In this article we’ll go over what a micron rating is, the difference between nominal and absolute ratings, and what each micron rating filter will remove from the water in your home. We’ll also look at other home filtration options, and touch on which filtration options are best for Aussie homes.

What Is A Micron Rating?

To understand micron ratings, we first need to understand microns. The term micron actually refers to a micrometre (μm) which is a unit of measurement that is equal to one millionth of a metre, or one thousandth of a millimetre. Particles as small as 40 microns can be seen with the naked eye – human hair, for example, is approximately 50 microns wide – while anything smaller than this requires the assistance of a microscope.

When referring to the micron rating of a water filter, the manufacturer is declaring what size particle the system can remove from your water. This means that contaminants that are smaller than the rating shown will pass through your filter without being eliminated, which can range from being no big deal, through to a significant health concern depending on what the contaminant is.

Does That Mean Smaller Is Always Better?

The answer to this question depends on your specific circumstances. While it is certainly true that a water filter system with a smaller micron rating will result in purer water, you need to consider the trade offs that come with your preferred level of purity.

Put simply, this is because as you go smaller in filtration capacity, you also slow down the speed that water can enter your home (and/or exit your tap) at. You’ll also generally find that water filtration systems that have smaller micron ratings are more expensive than their larger counterparts, which means you may not actually be getting the best value for money if you simply focus on the smallest micron rating possible.

You will also run the risk of clogging your filter and facing reduced efficiency if you select a water filtration system with a micron rating that is too small for the particles present in your water supply.
 

What’s The Difference Between A Nominal Rating And An Absolute Rating?

Before we get into what each micron rating filters out, we need to look at the difference between a nominal rating, and an absolute rating. While the distinction may not seem like a big deal, it’s actually rather important to understand if you want to make the best water filtration choice for your home.

Nominal Micron Rating

A nominal micron rating refers to an approximate value. While the micron size is accurate, not all particles of that size will be collected by the water filter. Generally this means that the filter will remove anywhere from 60% of the present contaminants at the specified size, however this is often impacted by factors such as water flow and filtration system type.

Absolute Micron Rating

An absolute micron rating means that your home water filtration system will remove at least 98% of particles at the specified size. Filters that have an absolute micron rating have undergone more stringent testing and can guarantee that they will remove a much larger percentage of contaminants.

What Does Each Micron Rating Remove From Water?

Now we’ve gone over what a micron rating is and what they different varieties are, it’s time to look at what particles and contaminants can be filtered out at each size. Filtration of all sizes will not be required under all circumstances, so it is important to consider your water source and filtration needs alongside the micron ratings of any home filtration systems you’re considering purchasing.

50 Microns

Water filtration systems that have micron ratings of 50 or higher are only suitable for removing larger particles. These systems will only remove visible debris and should be employed for the pre-filtration of visibly dirty water.

10 To 50 Microns

Home water filters that remove particles ranging from 10 to 50 microns will remove coarse debris and sediment that is invisible to the naked eye. They are generally also used for pre-filtration and are not suitable for high level filtration as a standalone solution.

5 Microns

Filters with a micron rating of 5 are capable of removing much finer contaminants. This includes silt, rust particles, mould spores and some bacteria. Although suitable for use as a standalone filtration solution, it should be noted that filters with a 5 micron rating cannot remove all bacteria or cysts making them unsuitable for end stage filtration in applications where these are of concern.

1 Micron

A home water filtration system that removes contaminants as small as 1 micron will be effective against very fine particles. It will serve well as a general filter for your home, and is the largest size at which parasitic cysts like Cryptosporidium and Giardia (commonly found in tank water) can be reliably removed.

Less Than 1 Micron

Home filtration systems with micron ratings smaller than 1 tend to focus on bacteria elimination and reverse osmosis. They require pre-filtration to perform effectively and avoid clogging, but are generally considered the gold standard. While these types of systems will provide the purest water, they can involve compromising on water pressure and are often significantly more expensive than other options, so it is important to consider whether the trade off is worth it for your situation.

Are There Other Types Of Home Water Filtration?

While most types of home water filtration will feature a micron rating, it is worth noting that UV filtration is also available. This type of filtration uses light to sterilise your water, and therefore does not have a micron rating as it is not a physical filtration method.

It is important to note that UV home water filters must be paired with a physical filtration system that removes particles larger than 5 microns in order to be effective.

Which Water Filtration System Is Best For Aussie Homes?

A water filtration system rated around 1 micron tends to be the most beneficial option for many Aussie homes. This is because a filter of this size removes the majority of contaminants, without compromising water pressure within the home. Having said that, this is a guide only and does not take individual circumstances into account.

For personalised support or to have a water filtration system designed specifically for your home, please reach out to your local Irrigear independent expert.