A charity has identified "high risk factors" at Pembrokeshire ponds where three people died in 2015.
A report was commissioned by the Carmarthenshire Water Safety Partnership on behalf of the family of Robert Mansfield who drowned in Pembroke's Mill Ponds.
Robert John Lyall, 57 and Wayne Anthony Young, 52, died in separate incidents.
Pembrokeshire council is responsible for the ponds and assessed them as low risk.
Dr Cliff Nelson from the Royal Lifesaving Society visited the Castle and Mill ponds in November and marked "not acceptable" high risks, including the water's temperature and depth, slipping and falling.
The potential outcomes he listed were drowning, hypothermia, limb injury from slips, trips and falls, and illness through water-borne pollution.
The report said risk of falling into the water around the ponds is "generally low" but there were a number of "pinch points" on the castle side where the path runs close to the river bank edge.
The assessment also found uneven surfaces that could lead to a fall into the water.
Dr Nelson said improvements to the path needed to be made and that railings should be considered.
He also identified a need for improved lighting and the regular maintenance of public rescue equipment.
At Mr Mansfield's inquest, the coroner Mark Layton raised concerns about Pembrokeshire council's risk assessment of the ponds.
"Given the number of deaths there is a real need to consider fencing, warning notices and lighting," he said.
Mr Mansfield's auntie, Sue Mansfield, said the family had been frustrated when the inquest was told the ponds were deemed low risk by the council.
"There is a very real risk there. We just want to make sure it is made safe so no-one else has to go through what we have," she said.
"Now we have had this report I hope the council will want to work with it - so far they have been quite welcoming of it."
A Pembrokeshire council spokesman said the council had "always taken these matters very seriously."
He said they had "previously undertaken a review of the walkway around the castle. The public footpath is inspected regularly and is considered to meet the intervention levels set for maintenance purposes."
"Nevertheless, in dialogue with the Carmarthenshire Water Safety Partnership last summer, we acknowledged they may well wish to undertake an independent review and noted that we would be happy to review such a study."
The spokesman said that the council was "saddened to learn of the incidents on the ponds" and, following Mr Mansfield's inquest, it said it would review safety.
It also replaced flotation devices which had been removed and erected signs at various points advising against swimming.
The spokesman added: "There is already lighting on the footpath below the castle and the installations were considered generally adequate."
Carmarthenshire Water Safety Partnership was set up in memory of Cameron Comey who fell into the Towy River in Carmarthen two years ago and has not been found.
Adam Whitehouse, chairman of the partnership, said the work they had done with the Mansfield family "in memory of Robert has been very emotional but rewarding."
He now hopes to continue working with Pembrokeshire council to make the improvements identified in the report.
Mr Whitehouse added: "Despite two out of the three fatalities at pond in 2015 being alcohol related, runners and walkers generally are one of the highest risk categories in recent figures, accounting for a third of all UK drowning fatalities."