• Water Consultant

Water Filtration System

When It comes to designing water filtrations systems in NZ, there’s a lot that comes into play, but first we need to define what is the meaning is of a Water Filtration System.

Quite often the term Water Filtration System is confused with everything from the likes of a carbon filter– which can be a filter but its primary function is that of a purifier. A purifier will generally remove taste and odor from the water supply.

Ultra Violet Filters is another term I’ve heard on many occasions. Ultra violet is used for disinfecting the water, but filtration is placed in front of UV 99.9% of the time to physically remove the dirt so the light can transmit through the water without any bugs hiding behind the dirt.

A filtration system is different to a purifier or steriliser. A filtration system physically removes solids from the water supply such as sand, some clay, iron in certain forms, leaves and dirt etc.

In heavily contaminated water supplies, a water filtration system usually starts of very coarse (could be a grill or grate) and as it works down to strainers that have elements that are measured in mesh sizing or millimetres or it could go to media filters that have a very high dirt loading and they have the added advantage of being able to reverse the flow of water to clean themselves which is a term called back washing. From there it could go to filter cartridges or elements which have pore sizes that measure down to microns. Most water filtration applications have filters that go down to 50, 20 and lower down to one micron. To give you an idea of what one micron is, it is 1000th of a millimetre. From here the measurements are measured in nominal or absolute sizing. Using finer filtration depends on the application and up to here it’s called particle filtration, but it’s not uncommon to use Nano-filtration or Reverse Osmosis when it’s called for.