Merriwa Water Supply
Update 3 December
Upper Hunter Shire Council is pleased to announce that recent radionuclide testing confirms that Merriwa's water remains safe to drink. The testing, conducted by Australia’s Nuclear Science and Technology Organisation (ANSTO), shows that the water has a radioactivity dose ranging between <0.2 and <0.34 mSv/year. This range is well below the Australian national reference level of 1 mSv/year.
The results were received late last week and have since been reviewed and verified by Council, NSW Health, and Department of Climate Change, Energy, the Environment, and Water (DCCEEW) Following a meeting with key stakeholders yesterday, Council is pleased to share this update to the community.
The Australian Drinking Water Guidelines (ADWG) screening value has been set to prioritise public health. These results confirm that the Merriwa drinking water supply is below the screening value . Upper Hunter Shire will continue to collaborate with the relevant agencies to ensure the safety of the community's drinking water.
Council will continue to monitor the drinking water in line with ADWG and NSW Health recommendations to verify the safety and quality of the water supply.
Update - 18 October at 09:03am
Upper Hunter Shire Council is still awaiting final results from detailed radionuclide testing by ANSTO, which has been delayed due to additional analysis required to verify initial findings. ANSTO advises that recent tests indicate lower levels of radioactivity than initially detected. The final report is expected in November. NSW Health confirms the water remains safe to drink, and Council continues using bores with the lowest radioactivity as a precaution. Further updates will be provided as soon as they are available.
Recent periodic testing, conducted in accordance with the Australian Drinking Water Guidelines (ADWG), has indicated radiation levels above ADWG screening values. NSW Health advises that continuing to use the water is unlikely to pose a health risk.
Upper Hunter Shire Council is undertaking further investigations in accordance with the ADWG and NSW Health advice. As a precaution, Council has moved to using the groundwater bores with the lowest radioactivity while the investigation is taking place.
Radioactive materials are naturally present in the environment, and everyone is exposed to low levels of radiation. Certain minerals that emit radiation can be found in drinking water, usually contributing only a small fraction to overall natural radiation exposure. Bore water is more likely to contain naturally occurring radiation, as it comes into contact with underground materials that emit radiation. Upper Hunter Shire Council is committed to ensuring the safety and quality of your drinking water, and is working with NSW Health and the Department of Climate Change, Energy, the Environment and Water on this issue. Further investigation is underway to assure the ongoing safety of the Merriwa drinking water supply.
The community will be informed of all developments as further information becomes available.
Frequently Asked Questions
NSW Health has advised that results above screening values do not mean the drinking water is unsafe. UHSC will keep the community updated with any new information. The Australian Drinking Water Guidelines use a reference level of 1mSV per year. As a comparison, the normal level of background radiation that most people are exposed to is approximately 2mSv per year and some medical investigations such as CT scans may deliver a dose as high as 10mSv. However, efforts should be made to reduce exposure where feasible if the annual radiation dose in drinking water is found to exceed 1mSv . As a precaution, Upper Hunter Shire Council is switching to using the two bores with the lowest radiation levels.
A radionuclide is an unstable form of an atom that changes to form a more stable atom, emitting particles called radiation. In Merriwa’s case, it involves Alpha and Beta particles, which are from naturally occurring sources.
Radioactive materials occur naturally in the environment and everyone is exposed to low levels of radiation. Some minerals that emit radiation can be present in drinking water and typically contribute a small amount to overall exposure to naturally occurring radiation. The radiation comes from the underground rock material that is in contact with the water.
NSW Health has advised that results above screening values do not mean the drinking water is unsafe. Further testing will provide more detailed information. NSW Health advises that the level of radiation is unlikely to pose a health risk NSW Health have assessed the maximum possible dose based on the current screen level results to be approximately 2mSv/year (milliSievert is a unit of radiation dose). The dose of radiation will be accurately calculated when the radionuclides in the water have been measured. Standard medical diagnostic equipment such as CT scans can deliver a dose as high as 10mSv.
Detailed radionuclide testing by the Australian Nuclear Science and Technology Organisation (ANSTO) is required, which will take approximately 10 weeks.
These results will allow the dose of radiation from drinking the water to be calculated. Knowing the dose will allow Upper Hunter Shire Council to plan its next steps, in consultation with key stakeholders (including NSW Health, DCCEEW). The community will be informed about these updates.
As a precaution, Council has switched to using the groundwater bores with the lowest radioactivity while investigations continue.
The radiation detected could originate from various materials found within the water source, and each different material gives a different dose of radiation. The activity of each radioactive material (radionuclide) in the water needs to be separately measured to gain a comprehensive understanding. This process is very time consuming.
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We are committed to ensuring your safety and keeping you informed. Updates will be provided on this page as more information becomes available.
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