District nurses are "over-worked" and there are "real concerns" about the pressure they are under, the Royal College of Nurses has warned.
The number working in Wales has fallen 42% in recent years, but the workload had increased tenfold, it has claimed.
And the union has also said district nurses would prefer to have more time to spend with each patient.
The Welsh Government said the number of nurses working in the community had increased overall.
Peter Meredith-Smith, associate director of employment relations at RCN Wales, said: "We do have concerns as to whether there is enough investment in the nursing workforce within our community services to ensure the highest quality of care to Welsh citizens.
"We also have real concerns about the pressure being experienced by frontline nurses working in community settings.
'Expectations are huge'
"They are, without doubt, over-worked and have less time to spend with each patient than they would wish to have."
BBC Wales' new political programme on S4C, O'r Senedd, spoke to Sian Lewis - a district nurse in Cardigan - who said her team's caseload had "doubled" over the past 10 years, seeing about 50 patients a day.
"Trying to fit 50 people into a day means we're busy and we have to drive quite quickly from one to another," she said.
"People's expectations are huge and sometimes we can't meet those expectations because we're so busy."
A Welsh Government spokesman said: "Health boards are keen to develop a more effective skills mix at local level, using highly-experienced district nurses to direct, lead and advise community nursing teams.
"As a result, the overall number of nurses providing community services has increased by 17% over the past six years."
Last week, Health Secretary Vaughan Gething announced £95m to train more healthcare professionals, including district nurses.
On the road with a district nurse
I spent a morning with Sian Lewis, a district nurse in the Cardigan area.
She told me things were "much busier" now than when she first started working in the community 10 years ago.
"Paperwork is more of a thing now and the patients have all got older so there's more of them with chronic conditions," she said.
There was a warm welcome waiting when she arrived at Tom and Muriel James' home.
Mr James, 92, said he would be in a home if it was not for the district nurses and his wife called them "angels".
Ms Lewis' visits mean the couple can avoid having to go to hospital or their GP surgery.
There is a political push to reduce pressure on other parts of the health service by providing more care in the community.
But that, of course, places greater strain on those nurses who travel from one home to another and whose caseloads are not limited to the number of beds on a hospital ward.
Hywel Dda University Health Board, which is responsible for NHS care in the area, said it had developed a number of "new and exciting" services to support district nurse teams and these all work in an "integrated way to provide the highest level of community care".
"The health board is very proud of the quality of the work accomplished by our district nurses and we wish to reiterate our gratitude on behalf of our patients and partners," said a spokesman.
O'r Senedd is on S4C at 22:00 GMT on Tuesday 28 February