Don’t know why you would want to have a toilet connected to a sprinker system or if in fact that is legal where you are – it certainly is not here. One way to overcome the problem would be to fit a PLV ( Pressure limiting valve ) after a Filtered ball valve feeding the line to the toilet. These can be purchased with preset outlet pressure settings and require no maintenace.
Selgas Services Ltd
Craftsman Gasfitters, Plumbers, Electrical Service Technicians