It's "hard to know" if Dubbo will be placed on a boiled water alert in the coming days, says Dubbo Regional Council director Julian Geddes.
A boil water alert was issued for Wellington on Wednesday, while Geurie residents have been unable to drink the town water since last Thursday.
Mr Geddes, council's infrastructure director, said it was due to the river water becoming quite turbid because of recent rain. The sediment in the river was making the water difficult to treat, he said.
"The boiled water alerts will be ongoing until the water quality increases or the council is able to meet the drinking water guidelines," Mr Geddes said.
"We reiterate the boiled water alert is precautionary and the health of our residents is our number one priority."
Water should be boiled if it's to be used for drinking, brushing teeth, preparing baby formula, making ice or washing fruit and vegetables.
For now, the Dubbo water is safe to consume because it has a different treatment plant with more processes in place, such as water softening.
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"It's hard to know [if Dubbo water will become a risk]," Mr Geddes said.
"It depends on the nature of the rain, whether it's nice steady inflows like we've had in the last 24 hours - which is probably okay - or if it's torrential downpour that increases sediment in the river. That could provide some challenging circumstances for us."
Regular sampling is done at the water treatment facilities three times a day and equipment is set up to send out an alarm if something is not right.
The director said his team was monitoring the situation at the Dubbo water plant very closely.
"We've had very dry periods before but we haven't seen the river in the condition like this," Mr Geddes said.
"The plants have and can cope with certain levels of turbidity but these are really challenging times and the river is of particularly poor quality at the moment."
Council is working to keep the alert as short as possible. However, Mr Geddes said there were things outside of his control, like the condition of the river.
In the meantime, Wellington and Geurie residents have been asked to restrict their water use.
"It gives the water treatment plant the opportunity to go offline for longer, to take longer to process water. If there's really high demands on that system, that's when it tends to have those challenges," Mr Geddes said.
He said the safety of residents was the number one priority for council.
Western NSW local health district health protection manager Priscilla Stanley said vulnerable people should be the most careful about the boiled water alert.
She said the major concern was some gastro symptoms as a result of pathogens in the water.