Water and Sewerage Authority officials have issued a warning after blue green algae was discovered in the Clypse Reservoir.
Although algal blooms aren’t always harmful, say some can be toxic and visitors to the reservoir are advised to avoid contact with the water.
Pet owners are also being urged not to allow their animals to drink from it.
Carers: 'They are often the quiet heroes of our Island'
It's believed there are around 1,000 young carers on the Island
Hooper: 'Time to bite the bullet and build new hospital'
MHK says government should be planning replacement for RDCH
'No final decisions' made yet about relocating dementia patients says Manx Care
Meeting due to be held with residents, families and staff
'We want to provide a facility for almost anybody'
Two women have one year keep Ballafesson Hall from being sold on open market
Relatives seeking clarity over potential plans to relocate dementia patients
Rumours there are plans to relocate Martin Ward onto specialist EMI unit