Official figures show the number of district nurses has fallen by 40% in the past decade.
However, NHS England says this has been countered by rises in other community staff.
The Royal College of Nursing and Queen's Nursing Institute say the situation is adding to the pressure on hospitals.
In recent weeks there have been repeated warnings that pressure on hospital emergency departments is unsustainable. Attendances have risen by 50% in the past decade.
For more than 150 years, district nurses have been supporting people in their own homes, keeping them out of hospital.
They are community team leaders, detecting problems before they become more serious, supporting patients after they are discharged from hospital, and caring for them in their own homes at the end of their lives.
Official figures from the Health and Social Care Information Centre indicate that a decade ago there were nearly 13,000 NHS district nurses in England. Last year there were fewer than 7,500. Many of those who remain are approaching retirement age.
Royal College of Nursing chief executive Peter Carter says the overall state of community nursing in the health service is "lamentable".
"With this huge reduction in the numbers of district nurses,  while at the same time the massive growth in the population and more and more people with complex conditions, I have to say unfortunately we really are failing people who deserve so much more."
Many district nurses feel overstretched. But for some the job remains hugely rewarding.
Janice Jones is a district nurse with Central Surrey Health, a not-for-profit firm providing community healthcare for the NHS. Here, staff satisfaction - at 96% - is much better than the NHS average.
"When you're doing your job you get to know your patient and their families and what their problems are. And you build up a relationship which is based on trust and respect, and you feel you're making a difference to their lives."
CSH has responded to the spending squeeze by cutting inefficiencies, for example using IT - including mobiles and laptops - to reduce unnecessary journeys and to access and share information. As a result CSH says the nurses have an extra hour each day to spend with patients.
He says that is leading to many avoidable hospital admissions, placing additional pressure on ambulance services and A&E units.
In a statement, community nursing charity the Queen's Nursing Institute expressed similar worries about the fall in numbers and "the loss of skills and capacity in community nursing teams".
"Qualified district nurses are specialist practitioners in community nursing and are absolutely central to patient-centred care in the NHS. High-quality community nursing services are imperative if we are to support people with long-term conditions to stay in their own homes, rather than be admitted to hospital."
District nurses told the BBC about their frustrations, including long working hours, having to see more patients in less time, and the burden of form-filling.
"Staffing is the number one issue," said one. "If you go to a shop and there aren't enough staff it's not the end of the world - people can wait. But when someone is in pain it really matters."
Another said she felt pushed for time from the minute she walked through the door.
"You try your best to meet their needs but there might be other things they want you to deal with, or just to talk about what's worrying them. There may be palliative care patients. You'd like to spend more time in a supportive role but there are only so many hours in a day."
In a statement, NHS England said although district nurse numbers had fallen, the overall number of community nurses - including other types of staff - had increased by more than 8%.
"What is important is getting the right staff to deliver the services patients require. To achieve this commissioners need to have clear and robust plans for community nursing services, both now and in the future."

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South Central Ambulance Service and South East Coast Ambulance sent out land and air crews to an area near the Discovery Centre at Swinley Forest, Crowthorne at 15:57 BST on Saturday.
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The man's death is not being treated as suspicious. His name has not yet been released.
The state of NHS community nursing in England is "lamentable", nursing leaders say.
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