Thanks, will try the roof seal.
It would be a huge job to empty it and it only drips at the moment.
As far as I know it's been leaking from day 1, about 5 years so I don't think the company are in a hurry to get it fixed.
It is auto filling so the water is never low. So it still serves its purpose.
It can't be emptied for safety reasons, it's been leaking for so long there are mushrooms growing around it!
I work in a care home and the sprinkler system tank is leaking from a weld in the tank. What sealant do you recommend using on a permanently...
Separate names with a comma.