Icon Water is asking Canberrans if they are willing to pay up to $400 more a year to fund improvements to water and wastewater services and protect the environment.
On top of pricing in an $82 increase to average household water bills in 2028, the water utility is eyeing additional spending that could cost a typical household up to $318 extra a year.
Territory-owned Icon Water has begun inviting customers to use an online "interactive bill simulator" to share their view on six investment priorities, including expanding the rollout of digital water meters and ensuring current levels of water and wastewater services are maintained.
The higher the level of spending a customer indicates they support for a particular priority, the higher their hypothetical bill rises. Customer responses will be used in Icon Water's pricing five-yearly pricing proposal to the Independent Competition and Regulatory Commission (ICRC).
"We are engaging with customers as we develop our 2028-2033 price proposal, so we understand their views on the services, outcomes and investment priorities that matter most," an Icon Water spokesperson said.
"We will continue to meet our regulatory obligations. This engagement focuses on the choices beyond those minimum requirements, including future service levels, customer experience and investment priorities."
Without any changes to Icon Water's current spending patterns, the territory-owned company expects the average quarterly residential water bill to increase from $336 this year to $356.50 in 2028.
If the highest levels of suggested investments were adopted, the average quarterly residential bill would hit $436.14, with the customer contributing an additional $318.60 a year towards the investment priorities.
ACT opposition government services spokesperson Peter Cain said a typical water and sewerage bill had risen 6.3 per cent this year and households could not afford more increases.
"Reliability is not an optional extra. This is softening people up for the next ICRC price grab,'' Mr Cain said.
"Families need cheaper bills, not another government monopoly asking them to click 'yes' to paying more. Canberrans deserve better than this."
Canberra Business Chamber chief executive officer Greg Harford said many local business would be concerned about the magnitude of the water bill increases being proposed.
"There impacts of water bill hikes will also flow through indirectly to businesses because they will leave households with less money,'' Mr Harford said.
"The impact of this, combined with rising interest rates, rising energy bill, rising taxes and other costs has a negative effect on consumer confidence and the broader economy.
"The Canberra Business Chamber understands and supports the delivery of a fit for purpose water supply system, but this is a challenging time for businesses and consumers."
The Icon Water spokesperson said the bill impacts on the simulator were indicative and designed to help customers compare the relative costs and benefits of different choices.
"We recognise cost-of-living pressures are affecting many households. At the same time, ongoing investment is needed to maintain safe, reliable and sustainable water and wastewater services for Canberra," the spokesperson said.
"Final prices are set by the ICRC under the ACT's established regulatory framework."
Icon Water paid the ACT government $47.8 million in 2024-25, including income tax equivalent payments of $25.1 million and dividends of $22.7 million.
More than 1700 people have completed the Water Budget Simulator, which will remain open until October 9.
Peter Jean is health reporter for The Canberra Times.