So you want them to eat better food but don't want to buy it?

Confusing to say the least...

Those special made gutloads are very well balanced and specialy designed for feeding your feeder insects, taking the best care of your animals starts with making sure their food is the best you can provide.., nothing to be cheap abouth if you ask us.

If you realy don't want to use them we believe that variation is verry impotant, as with every living thing that relies on food to stay alive.
You could use most types of vegetables, fruits, fish food, a whole bunch of different types of grains, oats, etc...

And yes, in most cases giving them tap water will be just fine, but using a water conditioner will always be more safe.