Memo 30 · Water · The Plan · ROI
The National Water Deficit
State-by-state desal trajectory vs MMC continental water network. Volumes, costs, productive value cascade.
Read →30,000 GL/yr captured from northern monsoon and inland flood. Stored at Alice Hub. Gravity-fed in every direction across the continent — north, south, east, and west.
Cons: the existing system and current trajectory. Pros: the integrated MMA corridor programme.
Six major existing east-coast desalination plants. NSW doubling Sydney Kurnell ($1.5–2 B). SA building Eyre Peninsula plus the $5–7 B Northern Water Supply Project plus Kangaroo Island expansion. WA constructing Alkimos ($2.8 B). SEQ committed to a new $4–8 B plant by 2035 plus Tugun expansion by 2033. Victoria expanding Wonthaggi from 150 to 200 GL/yr. None of these projects produces water at less than $1–2 per kilolitre, permanently.
Reverse osmosis requires continuous grid electricity at 3-4 kWh per cubic metre. Membrane replacement every 3-5 years. Continuous chemical dosing. Each plant employs 50-100 staff in shift work. There is no path to reducing these costs once a plant is committed.
Approximately 600 megalitres per day of hypersaline brine is currently discharged into Australian coastal waters. With the planned expansions this approaches 1,200 megalitres per day by the early 2030s. The cumulative ecological load on bays like Cockburn Sound is the open question no monitoring framework addresses adequately.
Perth's dam streamflow has fallen from 300 GL/yr in the 1970s to less than 50 GL/yr today — an 83% decline. Melbourne's storages reached 67.1% at end of summer 2026, down from 78.6% year-on-year. Adelaide's Murray River supply is increasingly stressed by upstream demand. The MDB Plan returned 2,750 GL to environmental flows, shrinking the irrigation pool. Without continental supply augmentation, the supply gap grows year on year.
Melbourne’s Victorian Desalination Plant operates at approximately 38% of capacity but consumers pay capacity charges every year regardless. Each new desal plant locks in another 30-50 years of similar payments while a national alternative is locked out.
Aggregate Australian desal nameplate output if every existing plant plus every planned expansion runs at maximum: 540–1,200 GL/yr. Projected national water demand by 2050 across residential growth, industrial reshoring, AI cooling, mining, hydrogen, agriculture, and climate-driven supply replacement: 23,000–30,000 GL/yr. The state-by-state trajectory covers 2–5% of what is needed. See Memo 30 for the full demand picture.
Every wet season, more than 200,000 gigalitres of high-quality northern monsoon and inland flood water flows from Australian rivers to the ocean. The resource exists. It is simply not captured.
Threshold pumping, ring dams, and Lake Eyre Basin flood capture targeting approximately 30,000 GL/yr at full corridor build — 12–15% of what currently flows to the ocean. This is not aspirational; the figure matches the projected total Australian water demand by 2050 across residential, industrial, AI compute, mining, hydrogen, agricultural, and climate-driven supply replacement. The water is already in Australia.
Pumping runs only during the 6-10 hour daily window when corridor solar generates excess power that would otherwise be wasted. Gravity-fed in every direction from Alice Hub at near-zero ongoing energy cost. No membranes, no filters, no chemicals.
No hypersaline brine. No multi-decade environmental load on Australian coastal bays. The system has no waste stream to the ocean.
The same conduit serves AI campus cooling, hydrogen production, corridor towns, southern irrigation, and PHES top-up. Capital cost is spread across multiple revenue streams.
Continental water supply, gravity-fed from Alice Hub, secures approximately $22 billion of annual agricultural GDP against the rainfall-decline trend. Australia’s food production capacity grows in step with global demand.
The water comes from northern Australia. The infrastructure is on Australian soil. Foreign control of strategic water supply is structurally impossible.
Programme-wide ROI summary → · Memo 30 (national deficit) · Memo 19 (cost) · Memo 20 (returns) · Memo 21 (counterfactual)
Each state water authority optimises for its own demand against its own supply. Each rational state-level decision sums to a national pattern that is structurally wrong. Tasmania, with hydroelectric water storage and high catchment rainfall, is the only exception. Detail: Memo 30 — The National Water Deficit.
Sydney Desalination Plant at Kurnell currently delivers 250 ML/day (15% of Sydney supply). NSW in detailed planning to double to 500 ML/day. NSW Productivity Commission: +4 million people in Greater Sydney by 2060. 85% of current supply is rainfall-dependent.
Wonthaggi plant placed at full 150 GL/yr order for 2026–27 — the first time at maximum capacity. Storages 67.1% at end of summer 2026, down from 78.6% YoY. Infrastructure Victoria: 65% of Melbourne's water from manufactured sources by 2050.
Adelaide plant at $1.83 B sunk. Eyre Peninsula plant (5.3 GL/yr) contracts finalised March 2026 with ACCIONA. Northern Water Supply Project (260 ML/day desal + 400 km pipeline to Olympic Dam) in detailed planning at $5–7 B. Kangaroo Island expansion advancing.
Dam streamflow has fallen from 300 GL/yr in the 1970s to less than 50 GL/yr today — an 83% decline. IWSS now relies chiefly on desalination and groundwater, not dams. WaterWest projects existing infrastructure delivers less than 200 GL/yr by 2050 against rising demand. Perth is the warning case.
Gold Coast Tugun plant at maximum 133 ML/day output under SEQ Drought Response Plan pre-drought phase. Seqwater committed to a new desal plant by 2035 at government-quoted $4–8 B. SEQ population projected to grow from approximately 4 M to over 6 M in the next 30 years.
Hydro Tasmania operates 30 hydroelectric power stations spanning 50+ dams — the storage system doubles as continental-scale water storage. Catchment rainfall remains plentiful. The other mainland states share none of these conditions: the problem is structural to the mainland, not bad luck.
Aggregate national desalination output if every existing plant plus every planned expansion runs at maximum: 540–1,200 GL/yr. Projected national water demand by 2050 across residential growth, industrial reshoring, AI cooling, mining, hydrogen, agriculture, and climate-driven supply replacement: 23,000–30,000 GL/yr. The state-by-state trajectory covers 2–5% of what is needed. The MMC continental water network delivers 30,000 GL/yr at full corridor build — calibrated to total 2050 demand — for less than half the aggregate state spend.