Ultra Violet vs RO Systems

UV Systems vs RO Systems Wahl Water Canada
*All comparisons are general and each system has detailed manufacturer operating and performance specifications.
*While uncommon, single tap applications are sometimes used for UV Systems. Whole house RO Systems are a possibility.


Comments & Perceptions
General Statements on Both Systems
  • There is a common misconception that UV Systems treat more than bacteria and provide "whole house protection" for water in a home.
  • RO Systems sometimes have the perception of removing "beneficial" items in water. 
  • UV Systems are often recommended as a solution for adverse water results in a Real Estate Transaction
  • RO Systems require time to remove contaminants. UV Systems provide immediate disinfection of the water.
  • UV Systems require Hydro to operate. RO Systems require water pressure and sometimes use a pump which requires Hydro.
  • UV Systems physically remove nothing from water. RO Systems use Filtration and a Membrane to reduce contaminants in water.


Ultra Violet (UV) - Bacterial Disinfection
Point of Entry (POE) 
Systems disinfect water using UV Rays to ensure that there are no bacterial contaminants which cause illness active in the water. This process physically removes nothing from the water and works by inactivating the bacteria. It is suited for treating an entire home or just one tap in some cases. They are installed where the water enters a home typically after a water meter or pressure tank for rural applications. Proper maintenance requires annual lamp changes, quartz sleeve cleaning and a plumbing disinfection.

A UV System is installed for bacteria (E-Coli & Coliform) and are sold commonly as Drinking Water Systems by hardware stores, water treatment dealers and plumbing companies. Most UV Systems are installed to treat an entire home and systems should be sized for the flow rate of water in a home. It is important that the water entering the system contain no hardness, iron, sulfur or tannin. Critical to the proper operation is the ability for the UV Ray to "see" the water and this means that the protective quartz sleeve surrounding the UV lamp must remain clean at all times.

Reverse Osmosis (RO) - Contaminant Reduction
Point of Use (POU)
Systems use a series of filters and a membrane to reduce contaminants such as chlorine, sodium, dissolved solids, lead, pcb's, herbicides, pesticides and chemicals. This process takes time to produce the water and is typically suited to a single drinking water faucet at the kitchen sink or refrigerator. They are installed under a kitchen sink or directly below the sink in a basement. Proper maintenance requires filter changes on 3, 6 or 12 months intervals and membrane changes every 2-3 years. Proper disinfection of the system should be completed with every maintenance interval. 

Reverse Osmosis systems would be used to remove sodium, chemicals and dissolved solids and are commonly sold as Drinking Water by hardware stores, water treatment dealers and plumbing companies. Systems require minimum operating pressures to work effectively and should not be operated on water that is micro biologically unsafe.

Conclusions About the 2 Systems
Summing up the Content
Each system serves a very different purpose and are often used together to provide safe water in a home or cottage. If you have an excessively high bacterial count in your water, a RO System is not the solution. Conversely if you have herbicides or pesticides in the water, a UV System is not the solution. Your water source is the first step in deciding which system to use and if it applies to the type of water in your home or cottage.