Is Mains Water Filtration really necessary?

Is Mains Water Filtration really necessary?

In an ideal world mains water would reach the end user pure and free from particulates. It is in the best interest of UK water suppliers to do everything they can to facilitate this expectation but a number of factors, including the quality, age and condition of pipework, corrosion and external influences makes it virtually impossible to deliver particle free water 100% of the time. So what can we do to ensure the water that is used within a building is completely clean, even if it did not arrive in that condition?

There is a broad spectrum of need for water filtration in buildings. Indeed, practically any water system can benefit from some form of filtration, be it to remove substances that are brought in externally, or substances that have found their way into the water system from within the building. When considering the water treatment system design, building designers often detail the requirements of softening, ultraviolet treatment and specific mineral removal, and overlook basic filtration.

The most basic level of water treatment in any building is particulate filtration; a particulate filter protects the building from stray sediment or debris that is present in natural water supplies. Unlike other parts of Europe, it is not currently mandatory in the UK to install filtration systems in new constructions, but there are significant long term benefits for the building and the end user by doing so.

The following photograph was taken in a cold water storage tank at a nursing home, after just six months in operation. The tank itself is a near-white colour, and brown particulate has settled at the base. The area where the base of the tank is visible is due to the turbulence of water flow in and out of the tank.


In this instance, the tank has become a useful ‘settling zone’ for the particulate, since the water is stored here temporarily before continuing to the rest of the building. If these particulates are not trapped on entry and allowed to continue into a building, the consequences can often be severe:

  • The impact of particles on equipment can be expensive and cause issues from more frequent maintenance and replacement.
  • Throughout the pipework of an internal water system particles can cause erosion/corrosion particularly in vulnerable areas like bends.
  •  Depending on where the particulate settles it can easily become a perfect environment for bacteria which can have severe detrimental effects on the health and well-being of building inhabitants. Less serious, but costly in fiscal and operational terms is the subsequent requirement for more frequent and intense cleaning procedures.
  • Adverse effects on water metering equipment, causing inaccurate measurements.
  • Particulate larger than 50µm can cause an effect known as ‘shadowing’ inside UV treatment equipment, allowing bacteria to pass through untreated because the particles have blocked the UV rays.
  • A build-up of particles can reduce the flow of water in the system and eventually cause complete blockages, necessitating significant maintenance.

If the water and water storage issues in this nursing home are not rectified, the effect on the residents’ health could prove to be dire, as they are likely to be particularly vulnerable to any contaminants.

In many industry sectors, including clinical and healthcare, catering and hospitality, and manufacture, clean and purified water is crucial for statutory compliance. Basic filtration is unlikely to meet those compliance requirements and procedures like reverse osmosis will ensure the water is free of all impurities. For generic builds and designs, filtering mains water may not be a necessity but it is certainly going to improve the sustainability of a building and demonstrate the ecological responsibility of the building services.