Wednesday morning marked one full week since Esther Wallace was reported missing from Federal Falls on Mount Canobolas.

Emergency service have estimated this is the timeframe a person is likely to survive on the mountain without food or fresh water.

There is no evidence Ms Wallace has died. Police say their sprawling search is continuing.

At an impromptu press conference on Tuesday morning Chief Inspector Gerard Lawson told journalists: "I can tell you that the search won't continue indefinitely but [we] do make an assessment every day.

"The longer she's missing, the less chance [there is] of finding her well. There are reasons why we are concentrating our search [on the mountain]."

Items of clothing potentially related to the investigation were recovered by SES and ambulance workers over the weekend and are undergoing testing.

The Central Western Daily understands homicide detectives have been engaged in the sprawling operation. This is standard practice in a missing person case and does not mean murder is suspected.

Esther Wallace was reported missing by a companion, who said they were separated while hiking at Federal Falls about one kilometre south-west of the Mount Canobolas summit.

A sprawling search of the circa-14-square-kilometre reserve has been underway since, comprising: Five NSW Police units, the SES, RFS, and staff from Cabonne Council, NSW Parks and Wildlife Service, and Forestry NSW.

Searching has generally run from about 8am to 7pm. Some smaller patrols have run through the night.

Last week police said they were "keeping an open mind" in the search. No further updates were available at that time.

The CWD understands dog and aerial search teams from Sydney had been on standby over the weekend but were not used.

Helicopters could be heard overhead in the State Recreation Area on Friday evening. Fire trails and access roads have been severely damaged by heavy recent rain.

Officers from Central West Police District, the Police Rescue and Bomb Disposal Unit, PolAir, Chifley Rural Crime Investigators have contributed to the search.

A spokesperson for the SES said on Thursday: "A good rule of thumb is 48 hours at this time of year, you really want to be finding something."

Esther Wallace is 47 years old and of Caucasian appearance with blonde hair. Police believe she was wearing an orange jacket, black pants, and sandals at the time of her disappearance.

Anyone with information on the woman's whereabouts are urged to contact Orange Police Station or Crime Stoppers 1800 333 000.

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