Blog - UV Sterilisers

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What is a UV Water Steriliser?

Ultraviolet sterilisers use ultraviolet (UV) light to kill 99.9% of bacteria and other potentially harmful micro-organisms that can be present in water. In many cases they are used for untreated water from a private supply such as a well, stream or borehole, the sole water source for about half a million people in the UK.

UV water sterilisers differ from most other types of water filtration system in that they do not improve the taste of the water or remove sediment and therefore will usually need to be paired with another type of water filter system.

What is UV Sterilisation?

Sunlight has long been known to have qualities that help to stop the spread of harmful bacteria. This is because light in the ultraviolet spectrum alters the DNA inside these harmful micro-organisms meaning they cannot reproduce; effectively limiting their ability to spread.

What does an Ultraviolet Steriliser do?

A UV system uses the sterilisation properties of UV light to kill harmful bacteria and other micro-organisms in the water. This is done by channelling the untreated water through a tube with a UV lamp inside to expose any harmful bacteria to the intense light, instantly sterilising it in the process.

There are a number of health risks that arise when drinking from a private water supply, and, in rare cases, some municipal water supplies where infrastructure has deteriorated and facilitated bacterial outbreaks.

Furthermore, more and more people are now using rainwater harvesting to collect drinking water, however this water (even though it’s fallen from the sky!) also needs to be treated as it can contain disease-causing microorganisms.

A UV system, therefore, can give you peace of mind by neutralising a range of bacteria, viruses, protozoa and oocysts (parasites) including:

E. Coli

Pseudomonas

Rotavirus

Legionella

Clostridium perfringens

Coliform bacteria

Please note that most standard UV sterilisers do not kill Giardia lamblia cysts or Cryptosporidium, which can be removed with higher specification UV sterilisers or other water filtration systems.

Different micro-organisms require varying strengths of UV light to neutralise them, with the lamps inside UV sterilisers specifically designed to counteract the widest possible range of illness-causing micro-organism.

Depending on the brand and how much water needs to be sterilised per minute, the UV system can be set up differently, however most of the components remain the same:

UV lamp: The most important element: these high-strength bulbs prevent harmful bacteria from reproducing.

UV Quartz Sleeve: This tube protects the UV lamp from the water, but allows the UV light to pass through.

UV Chamber: This houses both the lamp and quartz sleeve, and controls the amount of water passing through.

Control Box/Power Supply: The controller unit modifies the electrical output of the unit as well as providing a lead to an electrical supply.

What are the advantages of using a UV Steriliser?

The main advantage of using a UV steriliser is that it actively removes 99.9% of micro-organisms from your water without affecting its taste, smell or appearance.

Another positive aspect of using a UV steriliser to treat your water is that it is ‘always on’ and will work 24 hours a day. In addition, these systems are extremely energy efficient, meaning that in most cases they will not cause any dramatic increases in your monthly energy bills.

UV systems are relatively easy to install and maintain, requiring little or no specialist knowledge. You will need to replace the UV lamp and quartz sleeve every six months, although in some conditions such as hard water areas an increased cleaning schedule may be required.

• Kills 99.9% of bacteria and micro-organisms
• Works around the clock
• Small amount of maintenance needed
• Chemical-free
• Instant sterilisation: no water storage required

As with any type of water purification method, there are some disadvantages to UV sterilisers:

UV sterilisers aren’t effective at removing sediment, chemicals or heavy metals. It is highly recommended to include a sediment filter as many private water supplies will also contain unwanted solids which can shelter the micro-organisms from the UV light, leaving them to pass through the filter without treatment.

Andrew’s Water have a number of inline water filters or reverse osmosis systems to remove sediment, we have systems designed for dental and for domestic use.

As mentioned above, please be aware that not all UV filters kill every form of micro-organism, with both Giardia lamblia cysts and Cryptosporidium not removed by many types of UV system.

In addition to this, UV treatment does not actively improve the taste, odour or colour of your water. Please speak to our team if you require an additional level of filtration or have a specific form of micro-organism you are concerned about.

Selecting the right ultraviolet steriliser

Finding the right water filter system depends on a few different factors, which you should always research before buying a model:

• -Water Chemistry

If you are planning to use a UV steriliser on a mains water supply, the water chemistry will be more or less the same so you can ask for the exact details from your local water supplier and then decide whether you require a UV steriliser based on this.

However, in most cases UV sterilisation is for a private water supply. The first thing you will need to do is obtain a water analysis, which can be done through a few different methods:

• -Contacting the environmental arm of your local council OR
• -Employing a specialist contractor (can be found through your local council) OR
• -Taking a sample of the water from your supply and having it analysed by a laboratory

Once you have the results, you will be better placed to decide whether or not your water is safe to drink, and thus determine if you need UV sterilising equipment.

• -Amount of Water Usage

Once you know whether or not you require a UV steriliser, you’ll need to choose a make and model. The main factor in determining which model is best for you is to determine how much water you need measured in litres-per-minute.

The rough guide below provides an outline, but please be aware this can vary greatly depending on the number of occupants:

• -Small/low-usage households (1 kitchen, 1 bathroom) = 2-10 Litre-per-minute sterilisers.
• -Medium-sized/medium-usage households (1 kitchen, 2 bathrooms) = 8–20 Litre-per-minute UV sterilisers.
• -Large household/multi-use property (2 kitchens, 3+ bathrooms) = 20-50 Litre-per-minute UV sterilisers.
• -Commercial/industrial or other large-scale usages = 50+ Litre-per-minute UV sterilisers.

You may also want to consider the ongoing costs of your water filter as part of your decision-making process, with higher wattage UV steriliser bulbs consuming more energy as well as potentially being costlier to replace. Other ongoing costs include the UV Quartz Sleeves that need to be replaced roughly every six months depending on the make and model.

Once you know your specific requirements, please view the selection of UV water filter systems, or contact one of our team today.

Unsure of Which UV Water Filtration System you Require?

Due to the technical requirements involved in choosing a UV steriliser, you may find it difficult to choose without assistance.

If you would like any advice on the best UV steriliser for your specific needs, please contact the Andrew’s Water Team today.