How do I check if my water filter / purifier is working?

Often, customers ask us: how they can make sure that their water filter or water improvement system is working, and how to know when to renew filters or other parts. Or maybe you just want to know how efficient your water filter actually is in removing impurities.

Regular checking of the performance of your water improvement system is important:

  • to ensure it has been installed correctly and
  • that the cartridge/filter is performing. The amount of water consumption as well as the hardness of your water, influence how often a cartridge needs changing.
Top Tip: There are many different types of water filters on the market, ranging from simple water jugs, like Brita filters, to more complex systems like Reverse Osmosis machines or Ionisers. If you have not purchased a water filter yet, then we would recommend to test your water first in order to identify any contaminants or impurities in your water. This way you can make an informed decision about which ones you would like removing. Depending on the area where you live, the levels of impurities (like hardness, chlorine, metals ie. iron, copper, lead) in water can vary. A simple water test like the 13-in-One test kit, Total Dissolved Solids test and the Total Metal test can identify the current levels of contaminants in your water.  Once the water has been tested, it is easier to decide what impurities you would like to remove or reduce with your new filter. That way, you get the right water purifier that suits your water quality and needs. For a quick overview of the different types of filters available click here.

There are 3 simple steps to check the performance of your filter:

  • Step 1 – Identify what your water filter does (or should do)
  • Step 2 – Select the right water testing kit
  • Step 3 – Test your water

Step 1 – Identify what your water filter does (or should do):

First of all, check what impurities your water filter is designed to remove. This information is usually available on the packaging or in the product description. If you can not find this, then contact the manufacturer  to clarify. The most common impurities, which are reduced/removed by water filters include: chlorine, taste impairing substances* (usually hardness and chlorine), fine solids, heavy metals, pH, alkalinity, lead, iron and other metals.

–> If you can not find this information, then a simple multi-parameter test, like the 13-in-One water test kit is a good test to start with. Our 13-in-One allows you to test 2 water samples for 12 different key elements in tap water (nitrate, nitrite, hydrogen sulfide, total hardness, total alkalinity, total chlorine, free chlorine, chloride, copper, sulfate, iron, pH); and one sample for bacteria. It is best to test the water before and after it has been filtered and then compare the difference. The 13-in-One includes a table where the results of both water samples can be noted down and then easily compared to each other.

*Top Tip:  It is not always easy to understand which elements a filter has been designed to remove, as some manufacturers’ descriptions may not be clear.

Here are some tips:

  • Reduction of taste impairing substances: – this often refers to hardness, ie temporary hardness. Temporary hardness caused by calcium and magnesium hydrogen carbonate mostly affects the taste of drinks & food prepared with hot water. Hard water also causes limescale and scale deposits in appliances.
  • Another element, which impairs taste as well as odour is chlorine:– this can be present as free or combined chlorine, therefore it is recommended to choose a total chlorine test.
  • Reduction of heavy metals: – there are a wide range of metals which can be in water. This can be due to pipework (ie copper or lead pipes) or natural causes. Because of the wide variety of metals in water, it can be expensive to test every single one. Our total heavy metals test is an inexpensive way to check the overall total amount of metals in water.
  • Fine solids: – this can refer to small solids present in water, including minerals, salts or metals. A test for Total Dissolved Solids can measure the total amount of solids before and after the filtration process.

Step 2 – Select the right water testing kit:

Once you know the list of elements a filter should remove, you just need to select the appropriate water test, which will detect the levels of these elements.

  • To test for multiple elements, we offer a range of multi-packs, which can test the levels of between 5 and 13 different elements in water. Here is the link to our comparison chart.
  • To test for a specific test, we also offer a wide range of single parameter test kits, most of them containing 25 or 50 test strips. Click here or on the link for ‘Water Test Kits’ above.
Water Improvement System Main Purpose Suggestions for Water Testing Kit*
Water Softener Removes ‘hardening’ minerals like magnesium and calcium from water, which are often replaced with sodium ions (usually by increasing the salt content of water). Hardness test kits to test the hardness of water. As a result of the softening process, levels of salt (as sodium chloride) can increase, which can be harmful in drinking water. Carry out a Chloride test to be safe.
Water Ioniser Ionising may also remove contaminants from water, the main purpose however is to raise the pH as part of an alkaline diet. Some also claim to remove chlorine, chloramines, lead, bacteria, rust, arsenic and traces of pharmaceuticals. pH & Alkalinity, Total Chlorine test, Lead test, Arsenic test.
Reverse Osmosis (RO) for households RO systems usually use one or more filters to filter organic compounds, like salt and natural minerals, and often also bacteria and disease-causing pathogens. Most systems use different steps or filters to remove various dissolved and/or suspended species from water. Total Dissolved Solids to measure the total amount of mobile charged ions, including minerals, salts or metals dissolved in water. A pH & Alkalinity test and/or Total Metals test may also be used.
Biosandfilter A filtering method designed to re-model natural water filter methods using different layers of sand and other sediments. Multi-parameter kit like 13-in-One to test for coliform bacteria, nitrate, nitrite, hydrogen sulfide, total hardness, total alkalinity, total chlorine, free chlorine, chloride, copper, sulfate, iron & pH. A Total Dissolved Solids test and/or Total Metals test may also be used.
Gravity Water Filter Designed to mimick the natural flow of water through rocks and hence potentially remove bacteria, nitrates, chlorine, sulphates, heavy metals etc. Multi-parameter kit like 13-in-One to test for coliform bacteria, nitrate, nitrite, hydrogen sulfide, total hardness, total alkalinity, total chlorine, free chlorine, chloride, copper, sulfate, iron & pH. A Total Dissolved Solids test and/or Total Metals test may also be used.
Water Filter Jugs Mostly removing impurities from tap water, including calcium carbonate. Hardness test kits or Total Dissolved Solids.

(*This list is for recommendation purposes only and may not be complete. Each water improvement/filtration system may vary. Please check with the manufacturer for detailed advice on how to check the performance.)

Please note, that the water testing kits are screening tests only, they cannot be used to declare water as safe for drinking.

Here are some other tests for water filters / purifiers, which you might find useful:

  • Total Chlorine – check the total amount of chlorine, residue from sanitising the water
  • Copper – from copper pipes may leach into water
  • Total amount of Heavy Metals in water – various metals may occur naturally in water or enter the water through plumbing (ie copper or lead pipes)
  • Iron – another heavy metal which may be naturally present in water
  • Lead – from lead pipes or naturally present in water
  • pH – we offer a wide range of pH water tests

Step 3 – Test your water:

Simply follow the instructions on your water test kit and make a note of the results. We recommend testing the water before and after the filtration process so that the difference can easily be compared. If certain elements are in low quantity in the water before filtration, then there may not be a big difference compared to the post-filtration test.

Further Free Resources:

Got a question about water testing? Try our complete list of Free Water Testing Resources. Here are the most frequently read guides:

If you can’t find what you are looking for then please contact us, as we can source many other test kits. Discounts for bulk purchases available, please contact us to find out more.


Disclaimer: Only opinions based upon our own personal experience or information detailed in academic journals or other publications is cited. This has been done exclusively for anyone who is interested in this subject but is not intended to replace proper analysis. We cannot accept responsibility and liability of any kind which may result from the application of this information. We always recommend to consult an expert to discuss any test results or get a full recommendation on the specific subject and specific to your situation by an expert.

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There are strict standards for the quality of drinking water within Europe mainly laid down in the EU Drinking Water Directive (98/83/EC). These are based on advice from the World Health Organisation (WHO).