One in four social care services are failing on safety, the care regulator has said.
Analysis by the Care Quality Commission (CQC) shows that 23% of care homes, nursing homes and home care services require improvement on safety while a further 2% are inadequate.
Almost 20,000 people are cared for in the 343 services rated as inadequate.
Issues seen by inspectors include people being washed and dressed and then put back to bed to make it easier for staff, residents not getting enough to eat and drink, and people not getting help to go to the toilet in time.
When it comes to nursing homes, which care for people with the highest level of need, one in three are failing on safety.
Inspectors also raised concerns about organisations slipping down the ratings, with a quarter of those last rated as good deteriorating since their last inspection.
Andrea Sutcliffe, chief inspector of adult social care at the CQC, said some of the issues raised by inspectors "have a profound impact on people's lives".
She added: "From a safety perspective, it may be: 'Are there enough staff available to provide the care people need in their own homes?'
"If there is not, it may mean people have missed calls, people may be late to be supported to go to the toilet, to have the food and medication they need.
"These are things you do not want to be happening to your loved one or mum.
"If you're in a residential or nursing home, it may be that there are not enough checks and balances in place to ensure people are getting the right medication and the right support to eat and to drink."
She said failing services do not always treat people with dignity and respect.
"So, services where we have gone in first thing in the morning and we've found people who have been got out of bed, washed, dressed and put back to bed because it's easier for the night staff to do it than the day staff," she said.
This was "completely and utterly unacceptable" in the modern age, she added.
Ms Sutcliffe said other issues included a reliance upon agency staff who do not necessarily know the people they were caring for and were therefore not able to provide the services needed.
A failure to carry out proper checks on staff and poor staff training had also been highlighted by inspectors.
More than 21,000 adult social care services in England have been given a rating by the CQC in five areas: safety, leadership, and whether a service is caring, effective and responsive to people's needs.
Across these five indicators, 19% of services require improvement, 2% are inadequate, 77% are good and 2% are outstanding.
While most services are good and should be praised, Ms Sutcliffe said "nursing homes continue to be the worry area", with only 67% rated as good.
She said that "many of these homes are struggling to retain and recruit good quality nursing staff and this has an impact on their ability to provide good services".
Just over 1,800 services rated as good previously have now been re-inspected.
Of these, a quarter have deteriorated from good, including 5% that are now rated as inadequate.
"What it says to me is that there is a struggle for services to continue to maintain the high quality care that we know is vital and important for people," Ms Sutcliffe said.
"That, I think, shows the fragility in the sector and that good quality care is potentially precarious and we need to make sure that we're focusing on it and that we're not complacent about those good quality ratings."
But she said four out of five services rated previously as inadequate had improved at the point of re-inspection.
Caroline Abrahams, charity director at Age UK, said services across the country were patchy.
On nursing homes, she said: "You can be lucky but it's a bit like playing Russian roulette."
Overall, inspectors looked at 1,493 community social care services, 5,511 agencies providing care in people's homes, 10,858 residential care homes and 4,042 nursing homes.
Margaret Willcox, president of the Association of Directors of Adult Social Services (ADASS), said: "This report recognises that there is a lot of great care provided by committed leaders and staff through high quality services to people in care homes and in their own home."
She said extra Government funding was welcome but did not meet increasing needs and costs.
"The risk of adult social care approaching its tipping point is still real and we will focus on re-doubling our mutual efforts to ensure that the quality of care doesn't deteriorate and that older and disabled people and their families get the reliable, personal care they need and deserve."
Health minister Jackie Doyle-Price said: "While this report shows that the vast majority of people receive 'good' or 'outstanding' adult social care, it is completely unacceptable that standards in some settings are below those rightly expected by care users and their families.
"That's why we have introduced tougher inspections of care services, provided an additional £2 billion to the sector, and later this year we will be consulting on the future of social care in this country to put it on a stable footing for the future."
Shadow health minister, Barbara Keeley, said: "This report confirms that the social care funding crisis caused by this Government is now seriously affecting the quality of care across the country.
"Behind these statistics are thousands of vulnerable adults failing to get the medicines they have been prescribed, being ignored when they ask for help or having home visits missed."