One of my drains stayed in for about 4 days the other for 6 days. They wanted to discharge me from hospital with drains still in but I was very reluctant. Luckily, there wasn't any pressure to leave so I was able to stay (in an individual room). I'd never had drains in before so didn't know what to expect. I also saw congealing etc. in the tubes which concerned me but as I was still in hospital I was able to ask straight away.
I agree with what's already been said - ask the hospital staff for guidance. If you're no longer in hospital I think it's very remiss that they did not give you some guidance on what to expect when sending you home with drains still in.