Eyre Peninsula desalination is due to finish in December, at $470 million

The Eyre Peninsula Desalination Plant near Billy Lights Point is due to reach construction completion in December 2026 — roughly four months from now.

Main works commenced in August 2025, delivered by ACCIONA, which converted an Early Contractor Involvement engagement into the main works contract in July 2025.

At the same time, SA Water confirmed a cost increase to $470 million and a revised completion date of late 2026.

The essentials

The plant services water-vulnerable communities on the Eyre Peninsula, a region historically dependent on a constrained groundwater supply.

The ECI actually converted

This is the most useful thing about the project for a contracting audience.

ACCIONA was awarded the Early Contractor Involvement contract in November 2023. In July 2025, SA Water confirmed ACCIONA as main works contractor following that ECI process.

Early Contractor Involvement is used widely in Australian infrastructure and converts inconsistently. On CopperString, UGL and CPB Contractors remain preferred contractors for the EPC subject to approvals and financing, two years after the ECI. On Brisbane Stadium, two joint ventures are in ECI with a preferred bidder still to be selected.

Eyre Peninsula is a clean example of the model working as intended: a contractor engaged early, involved in developing the design and cost, then appointed to build it — with a revised, better-informed cost published at the point of conversion.

That the cost rose from $330 million to $470 million at conversion is not a failure of the model. It is arguably the model doing its job — producing a realistic number before main works rather than after.

The cost and schedule history

A 42 per cent increase and a nine-month slip across two years.

Set against the pattern in this series, that is comparatively modest. Snowy 2.0 more than doubled. Cross River Rail went from $7.7 billion to $19 billion. CopperString went from $1.8 billion to $13.9 billion. A mid-sized water project rising 42 per cent, with the revision published at ECI conversion rather than discovered during construction, is a materially better outcome.

The 2025-26 South Australian Budget allocated $155 million to the project in FY2025-26.

Progress

ACCIONA announced in May 2025 that delivery had commenced on the structural, mechanical and piping installation package. Geotechnical investigation began in April 2024.

For a plant due to complete in December 2026, structural, mechanical and piping installation starting in mid-2025 is a compressed program — which is worth watching against the date.

What to watch

1. Whether December 2026 holds. It is four months away.
2. Commissioning. As with every water and rail project in this series, process commissioning follows construction completion and is not the same event as the plant producing water.
3. Whether $470 million holds through completion.
4. SA Water's broader capital program, of which this is one of several commitments.

Published 1 September 2026 · Updated 7 September 2026