Sewage treatment plants in Perth's southern suburbs owned by the Water Corporation are shaping as assets likely to be put up for sale as part of moves to rein in WA's ballooning debt.
A confidential report that was mistakenly tabled in State Parliament last week reveals the plants are the "most notable" examples of Water Corp assets being examined for privatisation.
But the report, which was prepared by the utility to outline all the key threats facing it over the next five years, warned against any sales that would undermine it commercially.
It noted that privatising assets could compromise the Water Corp's ability to boost wastewater recycling rates in future.
Under its long-term strategy, the corporation aims to reuse 30 per cent of wastewater in WA by 2030 through measures such as injecting treated sewage into Perth's aquifers to boost drinking supplies.
Water Corp boss Sue Murphy, who is part of the task force convened by Government to advise it on asset sales, said selling assets potentially made sense.
Mrs Murphy said a private sector bidder might be able to run an asset more efficiently than the Water Corp or have access to cheaper finance, in which case everybody stood to gain.
But the utility would not sell anything if it left customers worse off. "Access to capital going forward over the long term is going to be more and more problematic," Mrs Murphy said.
"So, recycling capital by selling assets might be something that's worth looking at.
"But we need to make sure it's the right decision. What I don't want to do is leave our customers . . . paying more.
"If we can sell it and . . . get that service at the same price but we don't have to borrow the money, then that would be attractive."
Mrs Murphy also cautioned against selling off the most profitable parts of the utility and leaving it with marginal or loss-making parts of the business.
The corporation's debt is forecast to rise from $5.4 billion to $7 billion over the next five years.