Drinking water testing and Understanding the test results of your Drinking Water Test Kit

From our experts at SimplexHealth

Most countries have standards or guidelines regarding the maximum contaminant levels in drinking water. Globally, there is an overall agreement on the science behind the setting of these standards. Mostly, they are guided by worldwide research and the standards set by the World Health Organisation. The UK government has also published a set of water quality standards for key contaminants, which are guided by the European Union together with national standards.

It is recommended to record your water testing results and compare them to local guidelines.

  • If water comes from a private water supply, then it is important to test it regularly.
  • Should your drinking water test outside the desired values, then it is recommended to contact your local water supplier as soon as possible; or review your filtering system if you use water from a private source.
  • If a problem exists, then it is always a good idea to ask a neighbour, to see if they have the same problem to see if it is specific to your house.
  • Damaged pipes, internal storage tanks or piping systems can also be causes for problems and it is useful to check whether the problem arises from the mains-fed cold tap (normally the kitchen tap) or via the storage system (check the bathroom tap).
  • For lead testing or if lead is found in drinking water, then more information can be found in our short guide.
  • For more information about common contaminants/ elements in water and their potential effects, please also click here.

UK maximum contaminant levels or guideline standards for some key contaminants (to be measured at consumers’ taps):

Contaminant Concentration or Value Maximum
Aluminium 200µg/l (= 0.2mg/l or 0.2ppm)
Ammonium* 0.5 mg/l
Arsenic 10µg/l  (= 0.01mg/l or 0.01ppm)
Boron 1mg/l
Coliform bacteria (E.coli) 0 (none)
Cadmium 5.0µg/l (= 0.005mg/l or 0.005ppm)
Chromium 50µg/l (= 0.05mg/l or 0.05ppm)
Chloride* 250mg/l
Copper 2.0 mg/l
Cyanide 50 μg/l (= 0.05mg/l or 0.05ppm)
Fluoride 1.5 mg/l (= 1.5ppm)
Iron 200µg/l (= 0.2mg/l or 0.2ppm)
Lead 10µg/l (= 0.01mg/l or 0.01ppm)
Manganese 50µg/l (= 0.05mg/l or 0.05ppm)
Mercury 1.0µg/l (= 0.001 mg/l or 0.001ppm)
Nickel 20µg/l (= 0.02mg/l)
Nitrate NO3 50mg/l
Nitrite NO2 0.50mg/l
pH (Hydrogen Ion) between 6.5 and 9.5
Selenium 10µg/l (= 0.01mg/l or 0.01ppm)
Sulfate 250mg/l

*guide value rather than standard.

Conversions: mg/l = Milligrammes per litre, ppm = parts per million, µg/l = Microgrammes per litre

Some of the information above may vary, please check with local guidelines. More information about UK maximum contamination levels for other parameters, can be found on this website: https://www.dwi.gov.uk/consumers/learn-more-about-your-water/   (Drinking Water Standards Leaflet), this is part of the website from the British Drinking Water Inspectorate (DWI/ DEFRA).

What about non-regulatory parameters?

Most governments only regulate the maximum levels for the contaminants which are being seen as harmful. Other contaminants, which may be present in water, might be a nuisance but not harmful. Please always check with your local water supplier or plumber if an unusual concentration of specific contaminant has been found – often the cause can easily be removed.

Below is some information of how to understand the test results for non-regulatory parameters:

Alkalinity is a measure of the capacity of water to neutralise acids. Alkalinity is normally caused by presence of bicarbonate salts of calcium and magnesium, and very occasionally sodium bicarbonate may contribute. Alkalinity & pH of water are very closely linked. Testing both, the pH & alkalinity of water is important, as a very low or very high pH can be an indicator for problems with water quality. This is especially the case for water in swimming pools & spas, aquariums and private water supplies. Alkalinity in water can protect against sudden changes of the pH level. Spas should have Alkalinity of 80 – 160mg/l (ppm). If the alkalinity is below 80mg/l (ppm), then the pH can suddenly change. If a pH is too low, then water can be corrosive for metal parts, ie. lead from lead pipes can leach into water or metal parts may be damaged. If the pH is too high, then a desinfectant can not work properly. If the alkalinity is too high, then it can be very difficult to adapt or change the pH of water. Should it be necessary to change the pH as well as alkalinity of water, then it is recommended to adapt the alkalinity first.

Free and Total Chlorine:
Chlorine plays an important part in ensuring that water stays clean whilst it is being delivered to the home (sanitising effect). There is no legal limit or guide value on the levels of chlorine, the levels however should be kept as low as possible whilst ensuring the quality of the water. Should you notice a smell or taste of chlorine occasionally, then this could also be due to maintenance work. Homes which are nearer to the water treatment facility may notice the presence of chlorine more.
If you find the smell unpleasant you could fill water in a jug, then put it in the fridge to cool down before consuming it as cold water loses the smell of chlorine. Always remember to throw away any unused water after 24 hours and clean the jug regularly.

Hardness is due to calcium and magnesium salts dissolved in the water. The classification of when water is considered soft or hard varies depending on the author. The water hardness classification according to the US Geological Survey is as follows:
Soft water 0-60 mg/l, moderately hard: 61-120 mg/l, hard 121-180mg/l, very hard: >181mg/l (ppm)

Effects on your home:

  • Hardness greater than 80PPM: Detergents with softening agents are not completely effective in cleaning
  • Hardness greater than 120PPM: Some scaling will occur in pipes and appliances
  • Hardness greater than 250PPM: Dishwasher impossible to use without producing film on dishes

Potential solution: Could easily be removed using a water softener or certain anti-scaling products can help to prevent a build up of limescale in white goods.

For more information about common contaminants/ elements in water and their potential effects, please also click here.

What is in your water – Free Guide to Water Testing

Our experts at SimplexHealth have compiled a comprehensive guide to the most frequently asked questions, including:

  • What are the most commonly found elements in our drinking water?
  • Unusual colours, smell and taste of your water and how to identify the potential source
  • When and why test drinking water from the tap or a private water source
  • Understanding the results of your Home Water Testing kit
  • Lead in drinking water and what immediate steps can be taken to reduce lead exposure
  • Quick Product Finder
  • Top Tips on how to keep the water in your home safe
  • How to get the best drinking water with a water filter

Download the FREE Water Guide Here

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 purchase 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).