There are many different types of commercial water filtration systems used for water purity, each with their own advantages, disadvantages, and manufacturing route. Picking the right filter for your needs will depend upon a number of factors including throughput, types of material, rigidity of materials, safety, flow design, and their ability to deal with stress and strain. 

Commercial water filters have to follow certain design features since their two over-riding concerns are demand or throughput, and the ultimate cleanliness of the resulting water.  This means that the path between the input and output needs to be as short as is practical, while allowing maximum access to the filtration element.  To achieve this, the flow paths need to be carefully designed to maximise water flow and cleaning while still being a sealed package.  Water filter design has to consider certain must have elements, including;

Materials.  Any system being used to transport water for human consumption or human related systems have to pass stringent tests set by organisations who control products and material safety.  In the EU that can include the EHCA and national Government health agencies, while the Food and Drug Administration (FDA) oversees safety in the United States.  Almost every country worldwide has an official body that ensures that anything used for human consumption is of acceptable materials that will not cause harm.  Water pipes used to be manufactured from both lead and copper but these have been found to taint supplies and have been replaced by polymeric materials.  And water filters also have to abide by that legislation to, ensuring that they pose no threat to the people using them.  Polymeric materials are long-chain structures, which are generally robust, but may contain unpolymerized particles which can flow out with the water.  Legislation ensures that these cannot cause harm in biological systems like people.

Flow design.  While any water filter has to be constructed from materials designated as safe, they must also perform efficiently and maximise the flow of water going through them. This aspect has two fundamental functions; to allow the greatest flow of water while ensuring maximum filtration.  The filter designer needs to be able to balance these two elements, requiring a sound knowledge of flow characteristics such as venture effect, laminar flow, and the role of viscosity in order to create effective and safe filters.

Structural strength and stability.  The actual constituents and trace elements in water can vary greatly depending upon the area of origin and its source.  If impure water is being filtered. It can be assumed to contained elements and compounds which may affect the actual structure of the construction materials which could lead to premature failure.  The filter designer needs to ensure that materials will continue to perform exceptionally under all conditions.  This is also the case with accumulated impurities in the actual filter, which must remain in place until it is changed or cleaned out, without having any detrimental effects on the filter itself.

Because of the conditions facing a filter in its normal lifetime, materials and the design of the filter have to be sufficiently robust to be able to remain in place and operating as expected for what could be long periods of time.  This means that manufacturers have to be confident in their products, and ensure this through programs of continuous testing for both performance and longevity.  Filter manufacturers invest much time and money in making sure that their products are both fit for use, and will continue to perform as required.