Home care visits for the elderly, ill and disabled in parts of west London are being limited to just 15 minutes, it has been revealed.
Five out of eight west London councils book quarter-hour appointments, according to research by UNISON.
The trade union says such short time slots leave home care workers feeling rushed and unable to provide "dignified" care.
But some of those councils say the findings are misleading as they typically allow more time and only offer 15 minute visits when specifically demanded by those receiving care.
Council says 15-minute visits are 'very rare'
A Westminster City Council spokesman said: "The council does not commission care visits of 15 minutes unless at the request of the customer or for an exceptional reason.
"In some circumstances, such as administering medication, 15 minute visits can be appropriate, but only as part of a wider comprehensive care plan involving longer one-to-one visits.
"We always assess how long to give each vulnerable person on a case-by-case basis, but 15 minute visits are very rare and never done for personal care."
A spokesman for Kensington & Chelsea Council said it did not commission home care visits or 15 minutes or less unless specified by the customer for a specific reason, which was rare.
Nearly three quarters (74%) of the 152 local authorities across England which commission social care visits book 15-minute appointments, based on their responses to Freedom of Information requests by UNISON. In London, the proportion doing so is 45%.
Too rushed to provide 'dignified' care
UNISON's report Suffering Alone at Home, which was published on Friday, January 29, also found 74% of home care workers felt they had too little time to provide "dignified" care to the elderly and disabled people they visited.
Nearly two thirds (61%) said time restraints meant they frequently had to rush the care of people aged over 90, many of whom have dementia.
UNISON general secretary Dave Prentis said: "It is heartbreaking and distressing that many elderly and disabled people are not being cared for in a humane and dignified manner.
"Homecare workers have shared their harrowing stories with a strong sense of sadness, guilt, anger, and ultimately disgust, at a broken homecare system.
"Eye-watering cuts imposed by the government mean councils are still booking the shortest possible visits to care for vulnerable, frail and isolated elderly people.
"Homecare workers are often the only faces some people see all day, and they are a lifeline – only they can call for help and ensure that the housebound people they care for are fed, washed and well."
The Government has allowed local authorities to raise council tax by up to 2% specifically to fund social care, but Mr Prentis said the "crisis" was so great that in many places the extra revenue would "barely touch the sides".
getwestlondon has contacted Brent, Hammersmith & Fulham and Hounslow councils to give them the chance to respond.