Excessive drinking

My 11 year old Labrador has always been thirsty
But this last week he literally is drinking LOADS
I’ve got him booked into the vets next Tuesday but wasn’t sure if this should be expedited !
What am I looking at ?

 

I would ring the vets to get in sooner. There will be reason for the change in behaviour.

 

Thank you
Vet thought kidneys
Did blood tests
Urine analysis
He is on the boarder - have to do monthly testing now