Benalla Kilferra Raw Water Basin (Victoria) – Gross Alpha Activity
2020/21: Benalla Gross Alpha Activity 0.62 (Bq/L), Gross Beta Activity 0.44 (Bg/L)
A single result for gross alpha activity at the Kilfeera Raw Water basin in Benalla was reported
above the ADWG (2011) screening level. This result appears anomalous as historical
monitoring in the Benalla catchment has shown no previous concerns. Additional testing is
underway to investigate this result.
Radionuclides (Other beta- and gamma-emitting)
GUIDELINE
No specific guideline values are set for beta- or gamma-emitting radionuclides.
Specific beta- or gamma-emitting radionuclides should be identified and determined only
if gross beta radioactivity (after subtracting the contribution of potassium-40) exceeds 0.5 Bq/L (27.6 Bq of beta activity per gram of stable potassium).
GENERAL DESCRIPTION
Several radionuclides that are classified as beta-particle or gamma-ray emitters may occasionally be present in drinking water. The significant long-lived nuclides in this group are the naturally occurring isotopes potassium-40, lead-210 and radium-228, and artificial radionuclides caesium-137 and strontium-90. Tritium, another nuclide in this group, is present in the environment both from natural sources and as a result of nuclear fall-out and nuclear power generation.
Levels of strontium-90 and caesium-137 in the Australian environment have decreased substantially since atmospheric testing of nuclear weapons ceased, and these radionuclides are not detectable in drinking water. In the absence of a nuclear power industry in Australia, these nuclides are likely to be present in significant concentrations in drinking water only as a result of transient contamination following an event such as a nuclear accident.
Potassium‑40 occurs naturally in a fixed ratio to stable potassium. Potassium is an essential element for humans, and is absorbed mainly from ingested food. Potassium-40 does not accumulate in the body but is maintained at a constant level independent of intake. The average concentration of potassium in an adult male is about 2 g/kg of bodyweight, which gives an activity mass concentration of potassium-40 of 60 Bq per kg of bodyweight. The corresponding value for females is slightly less.
Lead-210, like radium-226, is a decay product of the uranium-238 series. Food is the most important route by which lead-210 enters the human body, and the annual intake depends on diet: highest concentrations are found in fish and other aquatic species. Generally, lead-210 concentrations in drinking water are considerably less than concentrations of either radium-226 or radium-228.
TYPICAL VALUES IN AUSTRALIAN DRINKING WATER
Concentrations of potassium-40 in Australian drinking water supplies vary widely, from below 0.05 Bq/L in surface water sources to more that 1 Bq/L in some supplies drawn from groundwater.
There are only limited data on concentrations of other beta- or gamma-emitting radionuclides such as lead-210, strontium-90 and caesium-137 in Australian drinking water supplies. Lead-210 concentrations are probably below 0.05 Bq/L and concentrations of artificial radionuclides are negligible.
2018 Benalla (Vic) – Lead
10/7/18 – Benalla (Vic) – Lead 0.025mg/L (max)
“The Benalla locality failed to meet the ADWG standard for lead in 2018-19…. A lead detection (0.025 mg/L) occurred as part of routine monitoring in the reticulation at Benalla on 10 July 2018. Results were received by the Corporation on18 July 2018. Test results from one other sites in the Benalla water sampling locality collected on the same day returned a result below the detection level of 0.001 mg/L.The sample site had recently been added to North East Water’s monitoring program in a new housing estate. A Section 18 was submitted to DHHS on the 18 July 2019 when the Corporation was notified of the exceedance. An Operator attended the side and visually inspected the sample site noting that the property had recently been constructed. The external laboratory resampled from this site and three other sites within the Benalla reticulation on 24 July 2018. All retest results for lead were received on 27 July 2018 and were all below the lead detection level of 0.001 mg/L.All other results for the reporting period in Benalla water sampling locality were below detection level.” North East Water Drinking Water Quality Report 2018/19
Lead Australian Drinking Water Guideline 0.01mg/L
“… Lead can be present in drinking water as a result of dissolution from natural sources, or from household plumbing systems containing lead. These may include lead in pipes, or in solder used to seal joints. The amount of lead dissolved will depend on a number of factors including pH, water hardness and the standing time of the water.
Lead is the most common of the heavy metals and is mined widely throughout the world. It is used in the production of lead acid batteries, solder, alloys, cable sheathing, paint pigments, rust inhibitors, ammunition, glazes and plastic stabilisers. The organo-lead compounds tetramethyl and tetraethyl lead are used extensively as anti-knock and lubricating compounds in gasoline…ADWG 2011
Benalla – Victoria – Manganese
2007/08: Benalla (Victoria) – Manganese 0.11mg/L (highest level)
Manganese: ADWG Guidelines 0.5mg/L. ADWG Aesthetic Guideline 0.1mg/L
Manganese is found in the natural environment. Manganese in drinking water above 0.1mg/L can give water an unpleasant taste and stain plumbling fixtures and laundry.
Benalla – Victoria – Iron
2007/08: Benalla (Victoria) – Iron 0.4mg/L
2012/13: Benalla Iron 0.37mg/L
Based on aesthetic considerations (precipitation of iron from solution and taste),
the concentration of iron in drinking water should not exceed 0.3 mg/L.
No health-based guideline value has been set for iron.
Iron has a taste threshold of about 0.3 mg/L in water, and becomes objectionable above 3 mg/L. High iron concentrations give water an undesirable rust-brown appearance and can cause staining of laundry and plumbing fittings, fouling of ion-exchange softeners, and blockages in irrigation systems. Growths of iron bacteria, which concentrate iron, may cause taste and odour problems and lead to pipe restrictions, blockages and corrosion. ADWG 2011
Benalla (Victoria) – Colour
2009/10: Benalla Colour 25HU
Based on aesthetic considerations, true colour in drinking water should not exceed 15 HU.
“… Colour is generally related to organic content, and while colour derived from natural sources such as humic and fulvic acids is not a health consideration, chlorination of such water can produce a variety of chlorinated organic compounds as by-products (see Section 6.3.2 on disinfection by-products). If the colour is high at the time of disinfection, then the water should be checked for disinfection by-products. It should be noted, however, that low colour at the time of disinfection does not necessarily mean that the concentration of disinfection by-products will be low…