The water firm highlighted desalination as a potential solution for guaranteeing drinking water supplies for the south coast's most populated areas in the next 25 years.
Its proposals emerged as the water plcs last week revealed their draft water resource management plans looking ahead to 2035. It is the first time the plans have been put out to public consultation.
Waste water recycling also features for the first time in some of the plans, as urged by ICE in its 2006 State of the Nation report (NCE 17 October 2006).
The UK will not be following Australia down the road of mass desalination plant construction however. The Sussex plants would be intended for use only when demand is at a peak. And the Brighton option may lose out to a scheme to augment upstream flows in the river Rother with recycled wastewater which can then be abstracted for drinking water treatment.
"It was considered that, on balance, while desalination offered the most robust solution in terms of resilience to drought, the recycling of the wastewater to augment the upper reaches of the river Rother was the least cost solution," a Southern Water spokesman said. A final decision will be taken after the consultation ends in 12 weeks.
A 5Ml/d desalination plant would be needed for Hastings after 2020 Southern said because water transfer from the Medway would no longer provide enough water.
Anglian, Wessex Water and United Utilities all investigated desalination and rejected it as too costly or too energy intensive. Thames is expected to go ahead with plans to build a £200M three stage reverse osmosis plant in Beckton, East London that will convert 80% of the brine abstracted to drinking water.
Using waste water to beef up river flows was a popular option with the water companies with water stress issues. Anglian is looking to boost upstream river flows with waste water rather than discharging it to the sea so it can increase abstraction for drinking water treatment in Peterborough and Ipswich. Southern, again, will be using it on the Isle of Wight and for the river Medway.
As the ICE predicted in 2006, putting effluent straight back into supply was "a step too far" for the water plcs.
Most of the firms tried to avoid promoting construction of new or expanded reservoirs. Only Thames and Wessex are actively promoting new surface water storage, Thames near Abingdon and Wessex near Bristol. But all the plcs are keeping a close watch on the development of the European Union Habitats directive, and in particular the "sustainability reductions" being proposed for it by the Environment Agency for river and groundwater abstraction.
If abstraction levels are reduced too far, Southern and Anglian will be looking for new storage sites.