What you feed you plants are what your plants will become. Take note of where your soil, fertilizers, and even source of water comes from. If purchased at a store the bag your soil or fertilizer comes in will state its origin.
If using non potable water be aware that unwanted organisms on a microscopic level may be present. You may be required to treat the water before using it. You do not want to introduce any unwanted or potentially harmful organisms to the plants you plan to eat.
Drinkable county water from the tap faucet is a good choice. Many counties will provide a mineral analysis including dissolved solids, pH, and salinity upon request. Your county may have it posted to the public on their website.
You can use filtration, conditioning systems, and ultra violet light to further enhance county water. For the home gardener though, county water straight from the tap is a reliable, consistent, and dependable water source for your garden.