By Geoff Adams-Spink
Age & disability correspondent, BBC News website
The closure of public toilets is leaving older people with incontinence isolated and afraid to leave home, according to Help the Aged.
It is estimated that provision has declined by 40% since 2001
More than half of the 1,000 people questioned said the lack of suitable facilities stopped them going out.
The charity says that too many local authorities are closing toilets in order to save money.
The Local Government Association (LGA) says that councils have often had to close toilets because of vandalism.
The Help the Aged survey found that 80% of older people found it difficult to locate a public toilet when they needed one.
And more than three-quarters of those surveyed said the toilets were not open when they needed them.
The charity is urging local councils to stop closing their facilities and to improve those that remain open.
Help the Aged says the isolation and inactivity caused by anxiety over where to find a toilet are detrimental to people's physical and mental well-being.
And it cites incontinence as the second most important reason - after dementia - for a move into residential care.
Six million people in the UK are thought to have some degree of incontinence.
The charity estimates one in 10 people over 65 experiences involuntary bladder contractions while 15% of older people still living at home have faecal incontinence.
"It violates human rights and denies dignity when councils are closing more and more public toilets," said Pamela Holmes, of Help the Aged.
"We have the very British taboo of bodily functions, yet one on three of us will develop incontinence at some point in our lives."
Help the Aged wants more research to be undertaken into the causes, prevention and treatment of the condition.
It wants to see the reinstatement of a national mapping exercise to determine the level of provision which, until 2001, was undertaken by the Audit Commission.
It is estimated that since 2001 toilet provision has fallen by 40%.
As people get older they need to use the toilet more often and frequently with greater urgency, according to the charity.
Those surveyed also mentioned hygiene and cleanliness as being vital considerations when deciding whether or not to use toilet facilities.
Local authorities have the power to open and maintain public toilets but are under no obligation to do so.
Help the Aged says that as budgets have become tighter, local councils have seen cutting toilet provision as a "soft target".
In London, the Borough of Richmond - faced with dilapidated public toilets - developed a Community Toilet Scheme.
The council recruited local businesses to allow the public to use their toilets without having to buy anything.
The business is paid £600 a year for maintenance and many owners have found sales have improved as a result of an increase in the numbers of people entering the premises.
The LGA says toilets are just one of many services that councils have to make hard choices about.
"In many instances councils have had no option but to close some public toilet facilities as a result of vandalism or persistent misuse by drug users and other criminals," said an LGA spokesperson.
The association says that in spite of escalating maintenance and staff costs, councils are coming up with innovative and inventive ways to tackle the shortage.
"Councils are committed to providing clean, safe and accessible toilets to the public where they are needed within the area."
And the spokesperson said that the government needed to ensure that local authorities had adequate resources to provide them where they are a priority.