SOUTH West Water (SWW) has announced £850 million plans to improve Cornwall's water and sewerage services, but said it will mean higher bills. Water treatment works in Falmouth and Bude will be upgraded, flood defences built at treatment work sites in Restormel, Drift and Falmouth, sewerage networks improved to protect the Fal Estuary shellfisheries, and sewers prone to blockages in Helston and Hayle tackled. The company is asking for customers' views on its draft WaterFuture proposals before they are submitted to regulator Ofwat later this year. Currently SWW is recommending bill increases of about 2.5 per cent a year, an average of £68, between 2015 and 2020, the period over which the work is due to take place. Customers already pay about £150 a year more than the national average and just two years ago faced an annual increase of 5 to 8 per cent. Despite the Government rebate of £50, the average bill is expected to be £520 in 2014-15, hitting £588 by 2020 if the proposals go ahead. Chief executive Chris Loughlin said: "We still need to invest in our networks. "There are also new challenges to face including population growth."