I drank lots of water with my anti biotics. Will that make it less effective? Can I also take vitamins with anti biotics?

No and Yes. Water consumption will not dilute the efficacy of oral antibiotics, and yes, you can take vitamins, but normal humans with normal diets seldom need vitamin supplementation. Usually a waste of money.
No and Yes. Water will have no effect on the antibiotic. And yes, you can take a regular multi-vitamin.