Sediment Filter

Sediment water filters (sediment filter) utilize mechanical filtration which works like a sieve by blocking and trapping sediments and other particles from the water as it passes through the filter medium.

Sediments are very common contaminants in both municipal water and well water.

Depending on their size and form, they can have a variety of negative effects like damaging appliances and plumbing fixtures, shortening/damaging the life of other filters down the line, as well as impacting the clarity, taste, and odor of your water.

This is where sediment filters come in handy.

They provide an effective and easy way to filter out sediments from the drinking water and improve its quality.

Sediment filters are quite reliable and can help reduce most of the problems associated with sediments present in water, plus they are often inexpensive and easy to maintain.

They are also available in different types for different applications.

The most common ones however are string wound, depth, surface, and spin down sediment filters.

Each of them offers its own set of benefits and downsides, so understanding their differences is essential to choosing the right one.

This comprehensive guide is going to cover all the important information about these filters and more.

Therefore, if you are looking to invest in a sediment filter, then this would be really helpful.

Keep reading to learn more.

Sediment in Water

Sediment in water refers to any solids or non-liquid particulate matter that’s present or found in well or municipal water. This includes materials like silt, soil, dirt, clay, and grains of sand or rust from corroded galvanized plumbing or water delivery pipes.

It can also be organic particles/materials of plants and microbes. The size can vary greatly from large rocks to fine silt.

The Problems

Sediments in water cause serious and costly problems or negative effects in your home. Some of these common problems include:

Clog Water System

The sediment debris can build up over time and create clogs through the entire water/plumbing system blocking up valves, fixtures, and pipes thereby resulting in narrower internal pipe diameters and reduced water pressure or water flow.

Particles of grit, iron oxide, and sand can equally clog the fine tubing and screens used in most of the home and commercial appliances such as espresso machines, coffee makers, beverage dispensers, and ice machines.

Damage Appliances and Plumbing Fixtures

All kinds of sediments can cause great damage to plumbing fixtures and home appliances that use or rely on water for operation.

The fine particulate matter, in particular, is abrasive and can prematurely wear out pumps, O-rings, faucet seals, and electric valves used in water appliances such as dishwashers, carpet cleaners, and washing machines.

As a result, the lifespan of these appliances would be significantly reduced making repairs more likely or leading to early failures.

The deposits of accumulated sediments inside these appliances can also greatly reduce their efficiency.

Impact the Quality of Your Water

Depending on the amount present, sediments can alter the taste and odor of your water, giving it an unpleasant earthy flavor or smell.

If you notice this, then it’s a clear sign that the problem is now serious enough to require action.

While fine sediment particles may not be visible to the eye, larger sediments present in the water can discolor it or cause it to look turbid.

A heavy presence of silt or clay can as well affect the clarity of your water making it look murky or muddy.

Can Affect the Performance of Water Treatment Systems

Sediments can prevent filtration systems like ultraviolet purification systems and reverse osmosis from operating efficiently or working correctly.

They can also have a detrimental effect on your water’s quality because viruses and bacteria tend to survive longer in water with high degrees of sediments than in water with little or no sediments.

For these reasons, sediment filters are highly recommended, especially for those that get their water from a private well.

A sediment filter will provide the necessary filtration of your water and protect all your water-using appliances and plumbing systems from damage. It will help enhance their lifetime and efficiency even if there’s no other filtration system installed.

What is a sediment water filter?

A sediment water filter is a specialized filter purposely designed to remove suspended solids and other particulate matter from the source water through a mechanical filtration process.

It basically blocks the sediments (such as rust, sand, silt, and other organic particles) from entering your home water supply or water filtration system.

They are normally rated by micron size – the smaller the micron size, then the greater the particle/sediment retention capability of the particular sediment filter.

How does sediment water filter work?

Most sediment water filters come in the form of a cartridge consisting of the filter medium that’s surrounded by a plastic housing.

The filter medium is usually made of different materials including polypropylene, polyester, ceramic, cellulose, cotton, glass fibre, and wound string.

The sediment filter/cartridge is installed at the point where the main water supply enters into the house, or at the sink.

It’s often installed as a pre-filter to first filter the incoming water supply before allowing it to pass through to other existing filtration systems or before it enters the home appliances and plumbing fixtures.

The filter works through a physical process known as mechanical filtration which involves blocking unwanted particulate matter from entering into a water supply.

The incoming water filled with sediments is forced through a thick bed of filtration media with tiny pores that have a diameter of between 1 and 80 micrometers.

As the water flows through this bed, all the sediments and other particles traveling in the water and are larger than the pores on its surface become trapped.

The media has sufficient porosity to allow clean water to go through to your tap or supply system while the sediments get caught and left behind in the filter.

It basically works like a sieve or dragnet that physically blocks and retains unwanted dirt particles as the water flows through the system, hence the water that goes into your home is free from particulate.

Depending on how the water enters and exits the unit, sediment filters can either be radial or axial flow filters.

Axial Flow Sediment Filter Cartridges

In this kind of sediment filter, the water enters from one end of the cartridge and then exits through the other end.

The filter medium (like granulated activated carbon) is located between the two ends and is loosely packed so as to allow water to pass through without much hindrance.

As the water flows along the axis of the cartridge, the filter medium traps the sediments.

The major drawback with these sediment filters is that the loose configuration of filter media may allow the creation of water channels that can allow certain sediments to bypass filtration.

The biggest advantage is that the water flow is fast (water goes through the filter medium quickly) due to the fact that they are not that quite restrictive.

Radial Flow Sediment Filter Cartridges

In radial flow sediment filter cartridges, instead of the water moving from one end to another as in the axial filter, the water flows in through the filter’s wall.

It moves only from the walls into the inner core of the filter and on to the outlet.

This arrangement forces the water to go through layers of filtration media which usually vary in thickness. They get tighter as the water moves further toward the inner core of the filter hence they are able to progressively trap smaller/finer particles lingering in the water.

Almost all cartridge-style sediment filters use the radial flow pattern and are what you are likely to encounter in the market – a good example is the wound string sediment filters.

Generally, the radial flow sediment filters tend to have a larger filtering surface area (about 15 times larger) than similar-sized axial flow filters because they utilize the entire circumference and length of the filtration media which makes them significantly more efficient at trapping sediments.

Their biggest downside is that the flow rate may be low because water can take more time to go through the tight layers of the filtration medium.

What’s actually removed by a sediment water filter?

The main contaminants removed by a sediment filter are suspended solid particles or visible particulate matter that includes sand, silt, rocks, rust flakes, debris, dirt, and natural organic materials like the remains of plants.

Sediment filters also reduce/remove turbidity from water which is the cloudiness or muddiness in water caused by the heavy presence of suspended solids.

Turbidity can cause the water to turn or appear yellow, orange, or brown.

A sediment filter can as well remove up to 95% of suspended or insoluble iron and manganese.

What they are not able to remove are chemicals, microorganisms (like bacteria), heavy metals, or dissolved solids.

They are mainly a defensive and preservative water filtration method for protecting sensitive water filtration components, plumbing systems, and home appliances.

This is the reason why sediment filters are usually installed (as pre-filters) coupled with other water purifying processes or filtration methods such as reverse osmosis and/or ultraviolet (UV) purification system(s).

Particle Size Ratings Of Sediment Filters (Micron)

Sediment filters’ capacity to remove particles is usually rated in microns (short for micrometer) which basically refers to the size of particles that the filter is capable of trapping or removing from the water.

Each micron is equal to one-millionth of a meter in size.

The micron rating for a particular sediment filter, therefore, means that all the particles larger than that specified micron rating will be trapped by the filter.

For instance, a 5-micron sediment filter rating means the filter will remove particulates that are larger than 5 microns or as small as 5 microns in size.

A 10-micron filter will capture everything that’s 10 microns and larger while a 50-micron filter would trap particles that are 50 microns or larger.

To put this in perspective, particles that are less than 35 microns are invisible to the naked eye – you can only view them under a microscope.

Another good example is human hair which is around 75 to 80 microns in size.

Typical sediment filters are normally rated at 20 microns, 10 microns, and 5 – 1 microns, or even sub-micron.

The smaller the micron rating, the smaller the size of particle the filter is able to remove.

However, keep in mind that although the smallest micron rating (sub-micron) is the most effective, it isn’t always the best choice because it’s the slowest.

Basically, the micron size of the sediment filter you select will depend on the kind of sediment you seek to remove from your water source or what purpose the filter will be serving.

For instance, if it’s a pre-filter for a UV system, then you will need a sediment filter with a minimum rating of 5 microns so as to clear out very fine particles.

A residential RO system can as well operate efficiently with a 5-micron sediment filter.

On the other hand, if you just want to clear out some particles in your water that may be clogging your appliances like washing machines or plumbing fixtures like the bathroom faucets, then a coarser 20-micron sediment filter would be fine.

For a whole-house sediment filter system, you may want to experiment with various micron ratings to find the desired results.

A great solution can be going with a dual gradient filtration system like a 50 to 5 micron with the very coarse 50-micron filter on the outside and the much finer 5-micron filter on the inside.

Nominal vs. Absolute Micron Ratings Of Sediment Filters

The micron size of sediment water filters can be further classified as either nominal or absolute.

Nominal Micron Rating

Nominal, according to WQA (Water Quality Association), means that the sediment filter is capable of filtering out at least 85% of all particles in the water-based on the specified size it is rated for.

For instance, a sediment filter that’s rated at 5-micron nominal should be able to remove 85% of particles in the water that are 5 microns or larger in size.

Absolute Micron Rating

Absolute micron rating, theoretically, means that the sediment filter offers a 3-log rejection, or can reject up to 99.9% of particles of the specified size which is virtually all the sediments or particles of the given size.

For instance, if a filter has an absolute 5-micron rating, then it should be able to clear out 99.9% of particles that are 5 microns or larger in size. Absolute ratings are normally used for purposes where efficiency matters a lot or for the tightest filters.

The majority of sediment filters though have a nominal micron rating. For most purposes, usually filters with a nominal 5-micron rating will be sufficient or effective enough.

However, when very high-quality water is needed or where a more thorough filtration is necessary like filtering out bacteria, cysts, or a parasite such as Giardia, then an absolute-rated filter would be the best option.

Sediment filters come in various types based on their configurations or filtration mechanism.

The four common types are string wound, depth, surface, and spin down filters.

Each has its own benefits and shortcomings, and understanding the differences between them is a vital step towards selecting the right one. Below are brief discussions of these 4 types of sediment filters.

String Wound Sediment Filters

String wound sediment filters are a form of melt-blown filters that consist of tightly wound cotton, polypropylene, or polyester string wrapped around a perforated core/axle to create a graded density/layers of filter material that’s capable of trapping particulate matter. They are able to capture particles ranging from 100 microns to a mere 5 microns.

Material and How it’s Made

String wound sediment filters are made of cotton, polypropylene, or polyester string which is wrapped all-around a perforated core/axle usually in a diamond pattern.

The way the string is wound is not uniform – closest to the core/axle, the string is wrapped very tightly together and as it continues to be wound further and further away, the winding becomes loose and spacious, compared to the winding closer to the core.

What this does basically is to create a density gradient or layers of filtration where the innermost layer of wound string is tighter while the topmost layer is fairly open.

As such, the tops trap only large particles and as the water moves further in, all the way towards the core of the filter, the increasingly tighter winding string stops increasingly smaller particles.

Performance

Due to the multiple layers of filtration with different micron sizes ranging from a larger rating (topmost layer) to a smaller rating (innermost layer) string wound sediment filters are considered relatively effective at removing sediment of different sizes.

They can provide in-depth filtration because as the water travels through the different layers down to the core, finer and finer particles are removed.

However, once string wound filters are overloaded with sediments, the strings tend to start loosening and shifting which can allow debris to slip back into the water.

Besides that, the string wound filters that use cotton as the primary material usually have the possibility of microorganisms building up inside the cartridge.

Therefore, you would want to look for a filter that uses synthetic fibers as the wound string because they are unconducive to the growth of bacteria and other microorganisms.

Application

Because they are able to capture large-sized particles on the surface and finer particles progressively as the water moves to the inner surface closer to the center core, wound string filters are much suitable for situations where the water has sediment with varying particle sizes.

They are, particularly, more efficient to deal with well water.

Lifespan

The depth of string wound filters allows them to capture a large number of different-sized particles before requiring replacement. They can fairly last long depending on the degree of sediments in your water.

The average lifespan is normally 6 to 8 months.

Pros

  • More efficient at filtering different-sized sediments
  • They provide in-depth filtration and can hold more debris without losing pressure
  • They don’t get easily clogged by larger sediment particles
  • They can last fairly long if the sediment level in the water is not high

Cons

  • Can allow debris to slip back into the water once the strings are overloaded
  • There are chances of bacterial growth in cotton string wound filters

Depth Sediment Filters

Depth sediment filters are cylindrical-shaped filters that much like string wound filters, utilize depth gradient to filter out sediment from the water. They have different layers that progressively block particles of various sizes down to less than 10 microns.

They are one of the most widely used sediment filters and can be of either wound string type or melt-blown.

 Material and How it’s Made

Depth filters are made of different materials with the most common ones being ceramic, cellulose, acrylic fiber, glass fiber, and polymers like polypropylene and polyester.

These filters are made by heating a polymer like polypropylene to its melting point and then blowing high-velocity gas through it forming intricately layered fibers of desired thickness.

These fibers are then collected and winded into one continuous fiber that’s highly porous.

The fiber has many small pores and is wound around a base thereby creating multiple filter layers that give it the ability to capture particles of varying sizes.

This process is often controlled by a PLC system which allows for changes in both the tightness of winding and thickness of the fiber as well as the thickness of the whole cartridge.

The polymers by themselves tend to be pretty firm hence they don’t usually require a core like string wound cartridges. Nonetheless, a core can be included in order to reinforce its structural integrity.

Based on the polymer used, depth sediment filters (melt-blown) are very resistant to chemicals. Moreover, unlike traditional wound string cartridges, the pore size is absolute since its’ pre-set in the PLC system, plus it’s unalterable.

As a result of this efficient design, melt-blown depth filters offer a great surface area to filter water, and the pressure drop usually experienced when water flows through a filtration system is significantly smaller compared to other methods.

Performance

The filtration performance of depth filters is quite impressive as they provide a filtering surface that comprises the entire circumference and length of the cartridge which allows it to capture sediments more efficiently.

Their main advantage though is their graded density structure (or rather their depth gradient) where the filter media becomes gradually tight as it nears the core of the filter.

The incoming water is forced through the different layers of the filter which become less and less porous as the water moves from the outer surface all the way into the center.

For instance, a particular depth filter might be designed such that it has a 50-micron outer layer, 25-micron 3rd layer, 10-micron 2nd layer, and a 5-micron inner core or even a final 1-micron layer.

So, filtration takes place through the entire depth of the filter as the water passes through these layers eliminating different-sized particles along the way.

The outer layers trap the larger particles like sand and dirt since they are more porous (have a high micron level) while the inner layers catch smaller and smaller particulate matter as the pores become increasingly smaller down to the center core.

This graded density design allows depth filters to capture not just more sediment but also particles of various sizes hence making them highly efficient – they are able to filter out finer particulate in their inner core.

There are even depth filters made of ceramic thatuniformly sized offer extremely tight depth – they often have absolute ratings with pores that are tight enough to trap microorganisms.

By design though, depth filters, especially ones made of polypropylene wear out faster. Once they get clogged with sediments, rinsing them out won’t restore any performance whatsoever.  They are meant to be disposable – the top layer may appear easy to clean after a rinse but it’s quite impossible to remove the finer particles that are trapped further within the filter.

Application

Depth filters are amongst the most common types of filters and because of their gradation, they are the best for filtering water that contains a variety of sediment contaminants that are of different micron sizes.

They are equally suitable for filtering out very fine particulates – the thickness of their media together with their construction complexity allows them to capture even the tiniest of sediment particles.

This makes them a great option as well for use with any other filtering system, especially RO and UV filter systems as they can offer great protection against damage and improve their efficiency.

Lifespan

While they are very effective at trapping a variety of particle sizes, depth filters tend to have a shorter lifespan in comparison to the other types of sediment filters.

They usually require changing every 3 to 6 months, but again this would actually depend on the amount of water that passes through the filter as well as the quality of the water itself (how clear it is or how much sediment it holds).

If your water supply is muddy or unclear you may need to change the filter more frequently.

Pros

  • Highly effective at filtering various different sized particles
  • They are ideal for filtering out very fine particles from the water
  • They don’t affect the flow rate of water that much

Cons

  • They tend to wear out faster than the rest
  • They require replacement – you can’t clean and reuse them
  • Flow rate can be slow if the inner layers of the filter are tighter

Surface Filters

Surface filters are also referred to as pleated sediment filters and are basically accordion-shaped filters that consist of a thin sheet of filter media folded into pleats which trap particles and other sediments on their surface.

They offer an extensive filtering area enclosed by pleats which allows them to hold large amounts of sediment.

Material and How it’s Made

Surface filters are made using thin sheets of cotton, polypropylene, polyester or any other filter media which are then folded into pleats forming an accordion-shaped pleated structure.

These pleats and their accordion shape create a broad surface area that holds the particles and sediment present in water as it passes through them.

Only the surface/pleated ridges of the filter trap the particles.

Performance

As stated above, the pleated arrangement of surface filters gives them much greater surface area compared to other types of sediment filters. The surface area of a filter is an important factor because the larger the area it provides the more holding capacity it has.

Surface filters utilize their broad surface area to trap large amounts of sediment within just the ridges of their peats. They can actually capture more sediment than depth filters.

To compare, depth filters usually have a large dirt holding capacity and are more effective at filtering out various particles of different sizes.

Surface filters, on the other hand, compensate for the lack of depth with a much larger filtering surface area, therefore, providing more capacity to trap much more particles and they are particularly effective at filtering out uniformly sized particles (particulates of the same micron size).

Another advantage is that as the pleats trap the dirt, a layer is created on the filter’s surface which further boosts the filter’s efficiency.

The trapped dirt becomes part of the filter’s mechanical filtration process hence allowing it to work optimally, especially at filtering out larger particulates.

Depending on the model, however, surface filters can capture particles that are as small as 0.10 microns.

They also provide less resistance to water flow hence there’s less pressure drop compared to depth filters. The extensive surface area allows them to trap a large number of particles without actually reducing the water flow rate.

That said though, the pressure will eventually be affected by the amount of sediments that build upon the filter over time.

Application

These types of filters are best for when you are filtering sediments that are all of the same sizes. Their broad surface area allows them to be manufactured in a way that can effectively filter particles of uniform micron size.

They are recommended too for filtering water that contains mostly large particles. The lack of depth means that they may not be that efficient at filtering out fine particles.

They can be used as pre-filters and as standalone filters also, based on the specific problem you’re trying to solve.

Lifespan

Most surface filters tend to often last longer than the rest, primarily because of the fact that filtration occurs on the surface which is quite large itself. They can work effectively for up to a year or more if the amount of sediments present in your water supply isn’t that high.

Once the entire surface of the filter is completely dirtied, then it’s replaced with another one.

Generally speaking though, these filters are frequently designed to be somewhat recyclable or rather reusable. They can be washed when they are clogged and rinsed to get rid of the trapped sediment and allow them to continue to filter with ease and be used again and again.

In some cases, they can also be unclogged by simply shaking or using some other means that will dislodge the trapped sediment.

Pros

  • Offer broader filtering surface area than the rest
  • Highly effective at trapping uniformly-sized particles
  • They don’t have a big influence on the water flow rate
  • They can last longer and some are washable and reusable

Cons

  • They are not quite efficient at filtering out very fine particles
  • A build-up of debris on the filter’s surface can reduce water flow over time

Spin Down Sediment Filters

Spin Down sediment filters are types of sediment filters that utilize a filter screen and centrifugal force to remove sediment matter from the water. They are a less common type of sediment filter and they are particularly designed to capture large particulates such as sand and rust chunks.

Material and How it’s Made

These types of filters are a little different from the typical cartridge-style sediment filters with regard to the design. They utilize a filter screen that’s made of polyester as the main filter medium.

The screen forms the center core of the filter and it’s housed in a clear exterior such that you can see how the sediments build up inside.

The sediment-filled water enters the top of the filter where it’s diverted into the clear chamber around the filter screen (which covers almost the entire housing).

The water is diverted into the clear chamber in a manner that circulates it through the filter housing and the filter screen. It’s swirled rapidly inside the chamber in a centrifugal motion upon which the sediments are pushed outside of the clear chamber.

The filter screens come in different mesh sizes (not measured in microns) with the mesh number representing the amount of hole per square inch in the screen or how small the particle is that it can block.

Examples are 120 mesh, 60 mesh, or 30 mesh.

The larger the number, the tighter the holes of the screen, and the finer the particles it will stop. For instance, a 250 mesh screen is able to capture smaller particles but it can clog easily compared to a 100 mesh screen.

Each spin down unit is also equipped with a flush valve that you open periodically to quickly and easily purge the collected sediment without taking the filter screen out of the housing or detaching the filter from the waterline.

Performance

As we mentioned before, all spin down filters utilize the principle of centrifugal force to circulate water through the clear chamber and push the heavy dirt and debris outside of the housing.

The filter screen prevents the sediments from passing through it hence they drop out of the water and settle down at the bottom of the clear chamber where they are collected to exit with the use of the flush valve.

This process is what enables the spin down filters to do the heavy lifting, allowing them to effectively clear out large chunks of differently-sized particles ranging from 100 to 15 microns.

Unlike the finer micron sediment filters, they are able to efficiently trap and remove large particles such as coarse sand, rust, shell, debris, grit, and pipe scale.

The size of the particles that can be removed will depend on the mesh number of the filter screen.

The common mesh size with micron equivalent is 100 mesh (around 150 microns) which is suitable for medium-duty filtration of sediments like grit, sand, pipe scale, etc.

Both coarser and finer filter screens are also available like 400 mesh which is able to remove particles that are 37 microns in size.

When it comes to operating pressure, most types of spin down filters are able to support water pressure of up to 150 PSI.

So, depending on the pipe size, they can support a maximum flow rate of up to about 90 GPM (gallons per minute) which means they are able to filter very dirty water at high flow rates than most of the other types of sediment filters.

They are usually offered in three different pipe sizes – 2 inches, 1.5 inches and 1 inch.

The 2-inch models can support flow rates of up to 90 GPM, the 1.5-inch model up to 50 GPM while the 1-inch can handle up to 20 GPM.

Application

These filters are ideal for well water because they are particularly effective at dealing with large particles.  You can install two of them with different mesh sizes so as to handle a large number of different-sized sediments.

For example, you can set up a 100-micron model at your main water entry and then a 20-micron model before the house to ensure overall filtration efficiency.

They can as well be used even in very clean city water to protect against sediment intrusion especially from unexpected breaks in piping.

They are ideal choices for whole house sediment treatment for medium to large particles such as sand and grit.

They can also be very effective as pre-filters for multi-level filtration systems or other finer filters like reverse osmosis and UV systems which can get clogged quickly by heavy sediments in the water.

Other areas they can be useful include in the agricultural sector, especially in drip irrigation, poultry growers water devices, and sand sensitive valves. They can equally work really well in both industrial and commercial environments.

Lifespan

Although the filter screens of most spin down filters are replaceable, they normally have a very long service life. They can be cleaned and reused, plus they don’t get clogged too fast like the cartridge-style sediment filters.

Once you open the flush valve, the full line pressure of the water purges the filter of all the collected and trapped sediments and rinses the filter screen thereby renewing it. You don’t need to take the screen out of the housing or remove the entire unit from the waterline.

The filter screen may require flushing every day or once a month, or even longer based on the amount of collected sediment as well as how much water is used.

You won’t have problems knowing when to flush out the filter either since most of these units feature a clear cover that allows you to view the screen and know when purging is needed.

The only notable downside is that the flush valve is likely to get ruined if you purge the unit very often.

Pros

  • Designed to efficiently deal with medium to large-sized particles
  • The filter screen is flushable and reusable
  • They provide high water flow rate than the rest
  • Have a small size that takes up little space
  • Screen sizes can be changed if required
  • Can be used in multiple areas

Cons

  • Allows small and finer particles to pass through
  • The flush valve can get ruined over time

Conclusion

A sediment filter is indeed essential not only in water treatment but also in preventing undesired particles from clogging and ruining your home’s plumbing system and appliances.

They come in various types for different applications as you’ve seen above.

The filter that you need will depend on where you live, your specific situation, and your needs like the flow rate requirements and exact particle sizes.

In general, the best sediment filter would be one that’s able to adequately clean up the water to the specified particle size with the least possible restriction in flow.

It should also have a reasonable lifespan.

Hopefully, this guide with all the information presented above can help you get a much better idea of what to consider or look out for when you are selecting your sediment filter.