UV water filters are best at destroying bacteria, viruses and other microorganisms in water. Unlike other types of filters that remove contaminants by trapping them in their filter media, UV water filters use UV lights to inactivate or neutralise bacteria, rendering them unable to infect again or even to reproduce. But this is not the actual reason why you need a pre-filter with an UV water filter. Pre-filters are not an optional addition to your UV purifier system, but rather a compulsory one, the reasons of which will be clarifed in this article.

uv water filter system, pre-filter

The factors determining the efficiency of UV water filters

To achieve the best results, water to be treated with UV lights has to be exposed to a certain dose of UV light (the minimum dose recommended by NSF is 40 mJ/cm2) for a certain period, and water has to be pre-filtered. The requirement of proper dosage and time exposure is necessary to be able to get rid of bacteria that react differently to different intensities of UV light and only get destroyed if they are exposed to the right levels of UV light. Cryptosporidium and Giardia are the two typical bacteria that need higher intensity and longer exposure times than other bacteria. Pre-filters are needed to remove elements from water that may block UV light from reaching bacteria and produce its effects. These hindering elements could be dirt, sediments, debris, absorbing compounds that can shield bacteria from UV lights or even absorb these lights. Once these particulates are removed from water, UV filters can achieve their full effectiveness.

Types of UV pre-filtration systems

Ultraviolet pre-filtration systems usually contain one of the following types of filter cartridges: polypropylene melt blown cartridges that have a high-dirt holding capacity, are non-leaching, and are resistant to chemicals; pleated sediment filters that offer good flow rates, are excellent at removing sediment and are cleanable and reusable; wound polypropylene sediment filters that are good at removing rust, silt, sand, and scale particles, and produce minimal pressure loss.

Usually, these filter cartridges have a 5-micron rating, but lower micron rating sediment filters are also available. The importance of sediment pre-filters cannot be overstated. Even though some UV water purifiers don’t come readily equipped with these pre-filtration systems, respectable UV filter brands will mention the need for such filters in their product descriptions. More complex UV purifiers like the Pentek 3.8 LPM UVS-110-2 UV Whole House Water Filter System already include the required sediment reduction filter.

Need a pre-filtration system for your UV purifier? Check out the following pre-filter systems on WaterFilterShop.co.uk: