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.
In Falmouth, up to £10 million will be invested to upgrade the treatment process and equipment at College Water Treatment Works, which will be near the end of its working life after 2015. The upgrades will improve the disinfection process and minimise the risk of taste and discolouration issues in tap water.
The flood defence work at the site follows problems at Tewkesbury in 2007, when flooding resulted in the water supply to 100,000 people being cut off for three weeks.
SWW says the aim of the work is to "protect against the most extreme weather".
Work in the Fal Estuary will minimise pollution risk by improving the quality of effluent entering the water.
"We want to work closely with landowners, the Environment Agency and shellfisheries to pinpoint what and where the main risks are and act to minimise them," said a spokesman for the company.
"This would benefit the fisheries by allowing them to make better-informed decisions on when or when not to lift their crops and lessening the chance of financial loss.
"We have identified Helston as an area where parts of the sewerage network would benefit from being upgraded to prevent collapses, flooding and pollution in the future.
"We need to undertake detailed investigations before we can confirm exact timings, location and level of investment."
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, the likelihood of more extreme weather and higher bathing water standards from 2015.
"Our aim is to invest in the right things at the right time to improve our services and give the region the reliable 'always there' infrastructure it needs.
"In some areas, if we don't invest sooner rather than later we could end up facing much higher costs.
"We should be able to keep future increases below the rate of inflation."
Customers can comment on the proposals online at www.southwestwater.co.uk/waterfuture from now until September 14.