It's also a required element so I guess a question might be how many micrograms of copper are consumed per day by using a copper lined bottle. Adults should get 900 micrograms daily unless they are also consuming a lot of zinc and then one must do more math. Gastric bypass surgery is thought to be a risk factor for copper deficiency. Usage of proton pump inhibitors may also contribute to copper deficiency by reducing the ability of the body to absorb dietary copper.

Most homes have copper water pipes. That's probably more important to test as corrosion in water bottles should be easy to spot. There are test kits one can buy to test their water at home.