wohi jo 'pure Urine' and 'water mixed with urine' main hai ..
Even though it is a good analogy from logical view, but makrooh and haram are not similar to what this example says. :)
Makrooh is 'allowed' but it is better not to consume or do that act.
Makrooh is actually opposite to 'Mustahib (not to halal)'. Mustahib is something which is not really forced to be done but it is better to do.
Water mixed with urine would still come in haram (forbidden) category to be used for consumption .
P.S. If someone is dying from thirst then it is not 'makrooh' to consume this water mixed with urine, using the analogy of haram being permissible to save life.
Mufti Diwana. ;)