Is there a shower water test kit out there? where I can test the shower water myself?

No one test would do that.

The water that comes out of your shower is exactly the same as the water that comes out of any other place in your house: sinks, toilet, outdoor faucets, washer and dishwasher unless you have a very weird plumbing system with two sources of water supply. You can take a sample to a water testing lab and have them analyze it. Google 'water testing' followed by the name of your town or city or county or state.

did you know that the water that comes out of your shower is the same water that comes out of the faucet in your kitchen?? You have only ONE place water comes into your house and it is then directed to the rest of the house. IF you live in the city, all your water is chlorinated which kills the bacteria...thats its job..Please don't tell me you believed those stupid commercials about dangerous shower water!

If you are really that fussed about it, then I would seriously advise you don't drink tap water.

Runoff from the shower is not an issue really.

Microbially, tap water is fine. The microbial loading (amount) is very low, and majority of organisms present are non-pathogenic, that is, they don't cause illness.

But chemically, tap water is dreadful. Many substances enter the water system thst aren't targeted for removal during treatment. Chloroform is a great example, metabolites of hormones (specifically female hormones from women on the pill) is another example. This was problematic in Germany a few years ago. Not sure if it's sorted now though.

But then if course bottled water has its drawbacks as well. Leachates from the plastic bottles are inevitable and are arguably harmful to some degree.

And then if course there is the completely unavoidable plastic leachates from the environment into our water table, which affects both bottled and tap water, and is somewhat unavoidable.

most local governments have a department that will do that, either free or for a small fee. Contact your town or city or county authorities.

But why would you want to test your shower water specifically? It's the same water you drink, and drinking water is more important to test.

But if you want to do it yourself, Amazon sells some. see link

Just mix clorox with your house water filter