When it comes to filtering tank water there are quite a number of options available, however they fall into two main categories; Point of Entry and Point of Use water filtration. Point of entry involves installing larger filters on the entry to the house thereby filtering all the water flowing into the house or through the house to external taps.
These filters need to filter tens of thousands of litres and are therefore larger with a higher capacity. They also tend to be coarser and not filter as fine (approximately 10-20 micron) to try and limit pressure reduction throughout the house. The Point of Entry Systems are generally not designed to treat the water to the same quality as Point of Use Systems although it is now more common to install ultra-violet (UV) systems along with the standard filtration to kill viruses, bacteria and other living microscopic organisms.
Point of Use Water Filters are designed to filter the water at one location where it is being used such as the kitchen sink. Water Filters and in some cases an Ultra Violet System are installed under the sink with a separate tap on the sink to dispense the water.
The filters are usually lower capacity and filter down to 0.3 to 1.0 microns. Bacterial cysts such as cryptosporidium and Guardia are generally removed along with heavy metals, chemicals, tastes, odour and sediment. These Point of Use systems are therefore smaller in size, lower in cost, easier to install and produce higher quality water. Once you have decided on the type of system you require, the next step is to decide the water quality you wish to have.