Drinking water quality

Our water is thoroughly tested to ensure it meets the standards set out in the Australian Drinking Water Guidelines. Testing is carried out regularly at our natural water sources, our treatment plants and reservoirs, and our customers' taps.

We've also adopted a Drinking Water Quality Management System (DWQMS)(PDF, 6MB) to ensure we provide the same standard of water across all our schemes. The system documents our approach to managing water quality from the catchment to the tap. It was developed with the involvement of NSW Health and outlines how we maintain our water supply to protect public health and meet regulatory requirements.

Water quality results in the table below contain a summary of water testing done at customers' taps during the last 12 months, updated quarterly.

Water quality test results summary - 1 October 2022 to 30 September 2023

Water tested at customers' taps

Water Quality Parameter

E. coli



Australian Drinking Water Guidelines criteria

At least 98% samples contain no E. coli bacteria

Less than 5 NTU

6.5-9.2* pH units

Water Supply System

% of results complying

% of results complying / average result

% of results complying / average result

Manning (services Crowdy Head to Smiths Lake, including Wingham, Taree, Old Bar, Hallidays Point and Forster-Tuncurry)



100% / 0.09

100% / 7.78

Tea Gardens (services Tea Gardens and Hawks Nest)


100% / 0.08

100% / 7.75



100% / 0.10

100% / 7.76



100% / 0.15

100% / 7.92

Gloucester (services Gloucester and Barrington)


100% / 0.14

100% / 8.21

North Karuah


100% / 0.67

100% / 8.01

Criteria based on health or aesthetic related value





NTU - nephelometric turbidity units                        

* Aesthetic guideline of pH  = 6.5 - 8.5. A value up to 9.2 may be tolerated, provided monitoring indicates no deterioration in microbiological quality as stated in Australian Drinking Water Guidelines.  

If guidelines for E. coli and total coliforms bacteria are not met MidCoast Water Services will issue a boil water alert to affected customers. Find out about boil water alerts below in Water quality issues.

Average hardness level per supply

Total hardness units





Tea Gardens

North Karuah

mg/L CaCO3/L(ppm)














German degrees







French degrees









Boil water alerts

If our water supply is contaminated by a pathogen such as bacteria or protozoa, we will issue a boil water alert to affected customers.

To find out more, read our Boil water alert FAQs.  

What is 'dirty' water?

'Dirty' water is a change in the appearance or colour of your water, usually to a brown or yellow.

This discolouration is caused by trace materials within the water, such as iron or manganese. When these materials enter the water supply system they are in extremely low levels. However, changes to the supply as it travels through the system can cause these materials to accumulate and become visible, discolouring the water.

Where and when does dirty water usually occur?

Residents living in areas furthest away from the nearest reservoir, or at the end of a street, may experience discolouration more frequently than others.

This is because the water has further to travel and this allows heavier particles to settle out of the water and become visible.

Weekenders or untenanted houses may also experience discolouration when first turning on a tap after an extended period of time without using water.

Discolouration can also be caused by old household connections as well as certain types of pipes. For example, discolouration will occur more often in houses with galvanised water pipes. Galvanised pipes are no longer used in homes. Copper and polyethylene pipes have become the norm. Anyone who experiences regular water discolouration and has galvanised water pipes in their home should consider replacing them and seek further advice from a local plumber.

Is dirty water considered a health hazard?

We constantly test the quality of drinking water in our area to ensure it complies with the Australian Drinking Water Guidelines. Generally dirty water is not a hazard to health.

What if I have milky or white coloured water?

Water that is milky or white in colour is the result of small air bubbles within the water.

This is usually due to air becoming trapped in the pipes, perhaps after the repair of a broken water main.

This water is harmless. If left in a container on the bench, the air will quickly dissipate and the water will become clear. It will not stain your washing.

Does dirty water affect washing?

Discolouration of the water supply by materials such as iron and/or manganese may cause a rust coloured stain on your clothing and linen while washing.

If you notice a discolouration in the water from your household taps, don't use your washing machine until the water is clear.

If you live in an area with frequent discolouration, regularly check your water before washing by running the tap in the laundry.

What should I do if I notice dirty water?

If you notice water discolouration in your home, we suggest you wait an hour or two then check that the water from your front tap (nearest to the water meter) is clear. If it is clear, go to the tap at the furthest point from your water meter (usually the garden tap in the backyard) and run the water for a few minutes until it also runs clear. If the water coming into your front tap is not clear contact us and we can arrange flushing of the water mains in the local area. While flushing is being undertaken, customers can experience very dirty water. However, this will clear shortly afterwards.

We have over two thousand kilometres of water mains, so we're unable to monitor them all at the same time. We rely on residents to advise us of any severe or ongoing discolouration to the water supply in order to take action in the immediate area.

Copper and rust in drinking water

Green copper stains on taps and in sinks and tubs

Copper pipe corrosion is generally responsible for the green/blue stains left on plumbing fixtures and in sinks and tubs. Internal corrosion of household copper pipes causes low levels of copper to leach into the domestic plumbing system, resulting in staining to these areas. This is more common from taps that are not used regularly and is more noticeable on white surfaces (such as a white bath). Replacing leaking tap washers and regular flushing your house lines can reduce this problem.

In more severe cases, tap water can have a cloudy blue-green appearance and sometimes contain blue-green particles, with an unpleasant, bitter taste. This can be an indication of higher levels of copper in the drinking water. Blue-green water must not be consumed and should be flushed for at least 30 seconds until completely clear, clean water appears.

Drinking water that has been left to stagnate for long periods of time in household copper pipes is often the main cause of elevated levels of copper.  

Brown stains on clothes washing and in sinks and tubs

Rusty, brown-coloured water from domestic taps can often be an indication of corroded galvanised pipework, which can often be found in older homes. Discoloured water can commonly appear first thing in the morning after no water has been used throughout the night, or after an extended unoccupied period.

Regular flushing of house lines can reduce this problem, but eventually badly corroded pipework will need to be replaced.

TIP: if you notice signs of copper or galvanised pipe corrosion in your home, running the tap for a short period (30 seconds) each morning can be an effective way of reducing levels of copper and other metals. If you have been away on holidays and there has been little or no water usage, flushing the house lines on your return can be helpful. Run the water from a tap at the back of your house to draw water through the internal plumbing (and give your garden a drink while you're there).

Green copper stains and brown rust stains can be removed with household stain dissolving products, such as as CLR. These are sold in most hardware or grocery outlets.

A qualified plumber can give you advice on domestic pipework.

All our water supply systems are monitored to ensure the water quality is within the Australian Drinking Water Guidelines and does not contain elevated levels of copper or other metals.