Anyone know where I can get a rin water diverter for a 50mm down pipe?
What's a 'rin' water diverter? Is that a make?
IMDF, you might try greenhouse suppliers.
Ah sorry you mean RAINWATER. Have you tried Google? There are dozens and dozens on there.
50mm does not seem normal for a house- so is it for a greenhouse??
But as has been said -google is your friend