Wollondilly Council has thrown its support behind the push to ramp up water restrictions in the greater Macarthur area and beyond.
Councillors decided to write to Wollondilly MP Nathaniel Smith, Water Minister Melinda Pavey and the opposition spokesman for water Clayton Barr requesting that separate water restrictions in the Upper Nepean catchment be considered based on current water storage levels.
The council will also advocate for tougher water restrictions across Sydney to help the dropping dam levels across the region.
Deputy mayor Matthew Gould raised the idea after Dilly Drought Drive members expressed their concerns about the falling water supply to him.
"This is an issue that is getting worse and worse," he said.
"The Upper Nepean dams currently average below 40 per cent capacity.
"Cataract Dam alone is below 30 per cent at the moment.
"The big challenge for us is that Warragamba Dam skews the statistics for the whole of Sydney due to its size - but we cannot access water from Warragama Dam or the desalination plant.
"Our only back up is Tallowa Dam and that is low at the moment too."
The Upper Nepean catchment area includes Cataract, Cordeaux, Nepean and Avon Dams.
Mayor Matthew Deeth said managing water supply across greater Macarthur was about to become even more challenging.
"We will have thousands of new residents moving into Wilton - let alone the growth happening in places like Camden as well," he said.
"How much population growth can our water supply withstand?"
Cr Gould hoped the letter would encourage politicians to look at broader strategies to deal with population growth and water supply.
Wollondilly Council will ask neighbouring councils in Camden, Campbelltown, Wingecaribee to also express concerns about Macarthur's water supply.
Camden mayor Theresa Fedeli could not confirm whether Camden Council would support tougher water restrictions in the Upper Nepean area but said it was incredibly important to conserve water.
"Level 1 water restrictions have been in place since June 1 and we've made a number of changes to ensure council is as water efficient as possible," she said.
"Sydney Water undertakes a thorough process when establishing the appropriate level of water restrictions.
"Council takes direction from, and complies with, the levels being enforced."
Campbelltown mayor George Brticevic did not respond to the Advertiser's request for comment.