Is it normal for my penis to hit the toilet water?

It's normal, if you're fairly well hung. It has never made me sick or have problems with my penis.

Well, depends on how close you are to the toilet. If the toilet is an average height [bowl is about 1.5 feet off of ground level], then it shouldn't hit the toilet [unless you're a small child using an adult toilet]. As far as it being okay for it to, that depends on what's in the toilet. If it's anything but your own urine [no fecal matter (poop) in the bowl], then it's probably not safe to do so. Because yes, urine is sterile 'till it hits that bowl. Millions of bacteria are in there and can grow in even the cleanest of toilets. If you put the tip of your urethra [pee tube] into the infected contents of the bowl you have a high chance of getting an infection. or inflaming the outside fo the head of the Glans penis. If it;s just clear toilet water, it's not as bad, but saliva [which can carry a lot of diseases] can dissipate quickly into clear toilet water, as well as some kinds of urine and cleaning chemicals [will irritate your urethra or outside skin of the Glans penis].

Does this happen while you're crapping, too?