Water supply testing  Merthyr Tydfil County Borough Council :
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Water supply testing 

This page provides information on private water supplies. 


What is a private water supply?


A private water supply is any water supply which is not provided by a statutory water undertaker or a licenced water company such as Dwr Cymru. A private water supply is NOT a mains supply.


A private water supply could serve a single property or it could be a large supply with a large network of pipes supplying water to many properties. A small supply will include any private water supply that provides less than 10m3/day (or serve less than 50 persons) to two or more dwellings.  Larger supplies will provide more that 10m3/day, or serve 50 or more people. Any private water supply that provides water to a commercial activity or public premises will also be classed as a large supply.


Private water supplies will typically originate from one of the following sources:


• Wells
• Boreholes
• Streams
• Springs
• Rivers
• Lakes or pond


Private Water Supplies (Wales) Regulations 2010 – What you need to know.


This legislation requires this authority to identify and maintain records of all private water supplies within Merthyr Tydfil. If you are unsure whether you are registered with this authority please complete the private water supply registration form attached to this page.


The Regulations place a duty on Local Authorities in Wales to sample and risk assess all private water supplies with the exception of private water supplies serving a single dwelling. The frequency of sampling and risk assessment is specified in the Regulations.


Merthyr Tydfil County Borough Council may make the following maximum charges for undertaking sampling and analysis, risk assessment and investigation:

With regard to single dwellings, risk assessments and sampling will only be undertaken be undertaken upon request and will also be subject to the same maximum charges.



Risk assessment (each assessment)


(note – charge not made for the first 5 years)




Sampling each visit *


(note – analysis fees are extra)




Investigation (each investigation)




Granting an Authorisation (each authorisation)




Analysing a sample –


taken under regulation 10:


taken during check monitoring:


taken during audit monitoring:










The Regulations set out procedures we must follow if we consider a Private Water Supply is unwholesome. This includes requirements to:

• Investigate the cause
• Inform the Private Water Supply user/s if the supply constitutes a potential danger to human health
• Give the user/s advice to allow them to minimise any such potential danger
• We will need to liaise with the Health Protection Agency to seek advice on whether there is potential to human health


Protecting your private water supply


All private water supplies can pose a threat to health unless they are properly protected, treated and maintained. Supplies can be microbiologically, chemically or physically contaminated and this may not be evident by the smell, taste or colour of the water.


Microbiological contamination is caused by certain micro-organisms such as e.coli, campylobacter and cryptosporidium. These micro-organisms can cause illnesses which are particularly harmful to vulnerable people such as the elderly, sick or young. This type of contamination is usually caused by animal faeces or discharges from cess pits and septic tanks.


Everyone who drinks contaminated water is at risk of infection. However there is generally a higher risk to those who do not drink the water regularly and are not used to it, such as visitors and guests. You should inform guests in your premises that you are on a private water supply so that they are able to make an informed decision regarding drinking the water.


Chemical contamination is caused by either use of pesticides, insecticides and fertilisers on nearby land or by naturally occurring high levels of chemicals in underlying rock strata.


Physical contamination may be caused for example by animal carcases in the collection tank or in the water supply.


To ensure your water supply is adequately protected from contamination there are some simple steps that you can undertake:
• Erect fencing around head works or inspection chambers so as to prevent access by farm animals
• Ensure water collection chambers and/or storage tanks are fitted with water tight, vermin proof covers and all associated brick work is in sound repair and condition
• Inspection chambers should be built above ground level to prevent the ingress of surface water and should be kept clear of overgrowth
• Regular cleaning, inspection and maintenance of your water supply is important to detect any defects and potential sources of contamination
• Ensure your water supply is not located near any discharge points from cess pits or septic tanks

It is advisable to boil your water prior to drinking if you suspect that your water supply has been contaminated.


Advice on water quality can be found on the Drinking Water Inspectorate website via the link attached to this page.

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