Yes, I have had to do it a few years ago.
I returned from holiday to find my rear garden and railway covered in sewerage, due to a blocked mains.
Fortunately Anglian Water's contractors were nearby, and they replaced all my shingle that the track was laid on and we washed all the track down using their high pressure jet washer and detergent the next day.
The layout had to be dismantled and rebuilt to do this, and all rail joiners had a small amount of copperslip added during reassembly.
No problems were found after the rebuild....