Water Filters

A water filter is the part of the system that is changed most often and raises the most questions. Choosing the right one rests on three pieces of information: the size of the housing, the micron rating of the filter and the job of the stage it sits in. When these three do not line up, the filter either will not seat in the housing, or fails to hold back the contamination expected of it, or upsets the balance of the system. With a cartridge filter the choice rests on three things: the type of filter, its micron rating and its position in the stage order. The replacement interval depends on the same three. For membrane selection see our RO Membranes category, and for valves our Control Valves category. Looking for a complete system rather than a replacement cartridge? See our under-sink water purifiers for drinking water, whole house water filtration for a flat, villa or building, and industrial water treatment for production lines.

What the Micron Rating Means

The micron rating states the lower limit of the particles a filter holds back. A 5 micron filter holds back solid particles larger than roughly 5 micrometres. A smaller micron figure is not always better: as the pores narrow, the filter clogs faster, pressure loss grows and the flow rate drops.

In practice the right approach is staged filtration. A stage that holds back coarse particles comes first, then a finer stage. The fine filter is then left to concentrate on its own job and lasts longer. On water heavy with sediment, using 5 micron on its own can clog the filter within a few weeks.

• 50–20 micron: Coarse sediment and sand. Usually handled by washable steel filters.
• 10 micron: Medium-level sediment. An intermediate stage on well water lines.
• 5 micron: The most common standard. The first stage of domestic and commercial systems.
• 1 micron and below: Sensitive applications. Pressure loss is marked, and a pre-stage must always come before it.

Cartridge Size and Housing Fit

Filter cartridges are made in standard sizes. The filter must be the size your housing accepts. The most common mistake is confusing a standard cartridge with a Big Blue (jumbo) cartridge.

Sediment Filters: Spun and String-Wound

Spun (polypropylene) cartridges

Made by compressing melt-blown polypropylene fibres. The structure is denser at the surface and looser inside. It holds back sand, sediment, rust and silt. Economical and widely used.

String-wound (yarn) cartridges

Made by winding yarn onto a porous core. The pore structure, graded from the outside in, lets it hold particles throughout its volume rather than only at the surface. At the same micron rating it offers more dirt-holding capacity than a spun cartridge, and extends the replacement interval on water heavy with sediment.

Big Blue and jumbo sediment cartridges

Washable steel cartridges

It is a stainless steel mesh screen and is not thrown away; it is taken out, cleaned and used again. Placed ahead of consumable cartridges it extends their life — on well water lines it is the investment that pays back most.

Carbon Filters: CTO and GAC

The carbon stage holds back chlorine and the taste and odour compounds that come with it. In reverse osmosis systems it also has a critical protective job: chlorine wears the membrane surface, so the carbon stage must always sit ahead of the membrane.

CTO carbon block

Made by pressing activated carbon powder into a block. Its tight structure lets it work both as a chemical adsorber and as a fine sediment filter. Pressure loss is slightly higher than with GAC.

GAC granular activated carbon

It holds a bed of granular carbon; the water makes contact as it passes through that bed. Pressure loss is low, so it affects the flow rate less. In reverse osmosis systems it is also mostly used as the final stage after the membrane.

In tank-type systems a bulk carbon bed is used instead of cartridges; for detail see our Activated Carbon Filters category.

Mineral, Alkaline and Taste Filters

Because reverse osmosis holds back the greater part of the dissolved salts, the water leaving it can be low in minerals and low in pH. The mineral and alkaline cartridges used in the final stage are fitted to raise those values.

Stage Order: How Filters Are Arranged

The stage order is not arbitrary. Each stage protects the next; when the order is broken, the expensive part is used up early.

Ready-Made Filter Sets

Buying a ready-made set matched to your unit, instead of picking the stages one by one, removes the risk of a size or ordering mistake.

• 3-Piece Filter Pack — 1,960.74 TL
• 3-Piece Filter Set — 2,696.01 TL
• Open-Housing 3-Piece Filter Set — 1,470.55 TL
• 5-Piece Filter Set — 2,941.10 TL
• 5-Piece Water Filter Set — 3,186.20 TL
• Open-Housing 10 inch 5-Piece Filter Set — 2,696.01 TL
• Industrial 20 inch Pre-Filter Set — 2,941.10 TL

How to Tell When a Filter Needs Changing

The calendar is a good starting point but is not enough on its own. How heavily the system is used and the quality of the water shift the intervals noticeably. The three signs below show that you need to act before the calendar says so. Intervals by filter type and the replacement steps are set out in our water filter replacement guide.

• A drop in flow rate: If the water from the tap has visibly slowed, the first suspect is the sediment cartridge. Taking the housing off and looking at the colour of the cartridge is usually enough.
• Taste and odour coming back: If you can taste chlorine, the carbon stage is exhausted. Once a carbon filter is saturated it starts to release what it had held.
• A change in readings: A rising TDS reading at the reverse osmosis outlet points to the membrane, and a falling pH points to the mineral stage.

Filter Housing and Connection Size

The clear or opaque body that carries the cartridge is called the filter housing. The housing needs to be right just as much as the cartridge; the housing size sets the cartridge size, and the connection size sets the flow rate of the line.

The most common inlet–outlet sizes on housings are 1/4″, 1/2″, 3/4″ and 1″. Under-sink units generally use 1/4″ push-fit fittings. On flat and building inlets you see 3/4″ or 1″ threaded connections; for set-ups at that scale see our building inlet water filters category. Reducing the connection size limits the flow rate of the line however good the cartridge is; when a housing is chosen, the connection size must therefore be taken into account alongside the cartridge size.

• 1/4″: Under-sink domestic unit, push-fit fitting.
• 1/2″: Small point-of-use applications, single filter housings.
• 3/4″: The most common size on flat inlets and Big Blue housings.
• 1″: Building inlets and high-flow commercial lines.

Housings that carry membranes are different and are built to withstand pressure.

Which Water Filter for Your Water?

The same unit behaves differently on different waters. Choosing the filter according to the particular problem in your water reduces both the cost and how often faults occur.

Mains water

Sediment is generally low and chlorine is present. A standard set-up is enough: 5 micron sediment, then CTO carbon. Chlorine control is the main job of the carbon stage and directly affects the life of the reverse osmosis membrane.

Well water

The load of suspended solids, iron and manganese is high. Rather than starting straight away with a consumable cartridge, putting a washable steel filter ahead of it brings the cartridge cost down noticeably. Strengthening the coarse stage is more effective than increasing the number of stages. For detail see our Well Water Treatment category.

Limescale-forming (hard) water

Cartridge filters do not remove hardness. A limescale problem is solved by ion exchange, that is by a softening system. The filter stage is used here to protect the softening system: sediment fouls the resin bed and upsets the working of the valve. Water softener installations must not leave the pre-filter out.

Water with a taste and odour problem

The carbon stage comes to the fore. Increasing the cartridge size for enough contact time — using 20 inch or Big Blue instead of 10 inch — makes a marked difference on its own. Because carbon starts to release what it had held once it is saturated, a late replacement makes the problem worse.

How to Extend Filter Life

The way to bring filter costs down is not to buy cheaper cartridges but to make the cartridge work less hard. The four practices below noticeably extend the replacement interval on the same system.

• Add a coarse stage. A washable steel filter is bought once and cleaned many times over. It extends the life of the consumable cartridge behind it.
• Move up a size. Using 20 inch instead of 10 inch, and Big Blue instead of standard, increases the filter surface. The same amount of water is spread over a wider surface, so clogging slows down.
• Keep the stage order. Moving the carbon ahead of the sediment finishes off the carbon cartridge within a few weeks.
• Get into the habit of measuring. Measuring TDS and pH prevents both early and late replacement. Early replacement means needless cost, late replacement means damage to the membrane and the equipment.

This category lists filter products. If you contact us with the brand and model of your unit, we can work out the right cartridge set together.

Filter Replacement Step by Step

On most systems a cartridge change is a 15–20 minute job. When the order is kept and the pressure is released, little is likely to go wrong.

• 1 — Close the main valve. Close the feed valve going to the unit. On systems with a tank, closing the tank valve as well prevents back-flow from the tank while you open the housing.
• 2 — Release the pressure in the line. Leave the filter tap open and wait for the pressure in the system to fall. Trying to open a housing under pressure is dangerous and can crack the housing.
• 3 — Undo the housing. Use the filter spanner. Housings generally turn anticlockwise. Do not forget to put a bowl or a towel underneath; the water inside will spill out.
• 4 — Take out the old cartridge and clean the housing. Rinse the sediment collected on the inner surface of the housing with clean water. Do not use abrasive detergent.
• 5 — Check the O-ring. This is the most common cause of leaks. If the O-ring is cracked, hardened or out of its groove, replace it; if it is sound, seat it properly in its groove and wet it lightly.
• 6 — Fit the new cartridge the right way round. Some cartridges carry a flow-direction arrow. Make sure the cartridge seats fully on the spindle in the centre of the housing.
• 7 — Tighten the housing by hand, then finish with the spanner. Overtightening crushes the O-ring and has the opposite effect.
• 8 — Turn the water on slowly and check for leaks. Open the valve gradually rather than fully in one go; check the connection points by eye.
• 9 — Run the first water off. Run the water for a few minutes, particularly if you have changed a carbon cartridge. The fine carbon dust that comes out at first use is normal and clears as the water runs.
• 10 — Note the date. Writing the replacement date on the housing or in your phone means the next service is not left to guesswork.

When a change is due, the 6-step procedure and the cost items are covered separately in our guide Changing Water Treatment Filters: When, How and Why.

Housing Maintenance and Service Life

A cartridge is a consumable part, whereas a housing is used for years — but not for ever. Clear housings go cloudy and brittle over time through sunlight and pressure cycling. If you see a crack, whitening or deformation around the thread on the body, the housing must be replaced; a body working under pressure that cracks will cause a flood.

Looking at the thread area and the O-ring groove of the housing at every change is a good habit. A build-up of sediment stops the O-ring seating fully and leads to leaks over time. For most housings the manufacturer recommendation is renewal at around 5 years; on clear housings that period is shorter where the installation is in direct sunlight.

Do You Need a Filter or a Water Purifier

These two terms are often confused. A filter separates out the solids suspended in water and the compounds carbon can hold back; sediment, chlorine, taste and odour fall within that scope. A water purifier, on the other hand, generally means a system containing a reverse osmosis membrane, and it also separates out the salts dissolved in the water.

If your problem is cloudiness, sediment, a chlorine taste or an odour, a filter stage is usually enough. If the problem is limescale, the answer is ion exchange, that is a softening system; a cartridge filter does not remove hardness. If you want to bring down the amount of dissolved salts, that is to lower the TDS reading, you need a system with a membrane. The most practical way to tell which of these three problems you have is to measure TDS and hardness; both give a result in a few minutes and let you choose the right investment.

6 Common Mistakes When Changing Filters

• Forgetting the O-ring when tightening the housing. The most common cause of leaks is an O-ring that has not seated or has dried out. Check the O-ring at every change and wet it lightly if needed.
• Putting a new cartridge into service without rinsing it. Carbon cartridges can release fine carbon dust at first use. Running the water for a few minutes lets it clear.
• Changing the stage order. Moving the carbon ahead of the sediment leads to the carbon cartridge clogging within a few weeks.
• Choosing the wrong micron rating. Using 1 micron straight away on water heavy with sediment clogs the filter quickly and drops the flow rate.
• Changing only the cheap stage. When the sediment is changed but the carbon is not, the taste and odour problem carries on, and the filter is wrongly assumed not to be the cause.
• Undoing the housing without closing the main valve. Opening a housing under pressure can cause both a flood and a cracked housing.

Jug, Shower and Fridge Water Filters

Many of the products people search for as a “water filter” are not unit cartridges but small filters used in the kitchen, the bathroom or the fridge. They do not do the same job as cartridge stages; knowing which need each one meets makes the right choice easier.

• Water filter jug: Works by gravity and needs no electricity or installation. Its replaceable cartridge acts on chlorine, taste, odour and sediment. Model: Water Filter Jug.
• Shower filter: Fits on the shower head or hose; it reduces chlorine and fine sediment but does not lower water hardness (limescale). Details: Does a Shower Filter Work? What It Removes and What It Does Not.
• Fridge water filter: Used in fridges with a water and ice unit; the cartridge type and change interval are set by the fridge manufacturer. Details: Refrigerator Water Filter: The Water and Ice Line.
• Limescale filter: Most products sold under this name do not lower hardness; we compare the differences in our article limescale filter.

If the dissolved solids (TDS) and limescale level of drinking water need to come down, these filters are not enough; a reverse osmosis water purifier is needed.

Domestic, Flat Inlet and Industrial Filters Compared

The same filter types are used at different scales and sizes. What decides the choice is the flow rate: how many litres of water will pass the point directly determines which size is needed.

As the scale grows, so do the number and the diameter of the filter housings; cartridges are connected in parallel to meet the flow rate. Industrial water treatment and industrial packaged systems call for a filter selection calculated from the total flow rate of the line and its operating hours.

Water Filter Prices 2026

The prices below are the current values on the product pages and include VAT.

Ready-Made Filter Set Prices

Ready-made sets are the most common purchase for yearly maintenance. The stage contents are taken from the technical details on the product pages; choose by comparing them with your unit's number of stages and housing size.

Cartridge Prices: 10, 20, 30 and 40 Inch

Mineral and alkaline stage: 5-Stage Mineral Filter 441.17 TL, pH Alkaline Filter 1,715.64 TL, pH Alkaline Mineral Set 2,205.83 TL, Pentek GS10-CAL/RO 2,205.83 TL, Taste Filter 490.18 TL. Ready-made sets range from 1,470.55 TL to 3,186.20 TL.

What Makes Buying Filters from Water Point Different

• This group is a consumable; because their life depends on water quality and use, they are outside warranty cover.
• CE certified products — we work with products that fall within certification scope.
• ETBİS-registered e-commerce — we are registered in the Ministry of Trade Electronic Commerce Information System.
• Invoiced sales — a legal invoice is issued with every order.
• Standard sizes held in stock — we hold stock of 10, 20, 30 and 40 inch standard and Big Blue cartridges.
• Free site survey available — if you are not sure which stage needs changing, we identify it first. see the details
• Türkiye-wide service network for industrial work — for domestic units we serve İstanbul and the surrounding provinces (such as Kocaeli and Tekirdağ).

Address: Mehterçeşme Mah. 1919 Sk. No: 54/B Esenyurt / İstanbul.

Cannot find the spare part you are looking for?

Send us the brand and model of your unit and we will work out the right filter, membrane, valve or resin together. The site survey is free if the unit is purchased from us; if only a site survey and measurement are requested, a site survey fee of 2,000 TL applies.