Hi Sharon: Rainwater reuse ...

Hi Sharon: Rainwater reuse as drinking water would be OK but the water should be modified by adding electrolytes since it will typically be electrolyte poor.  You should be able to add this to the water by a simple injector or by putting the collected water into a reservoir holding tank and adding electrolytes manually.  Drinking water with a low electrolyte concentration for a long period or time i.e., as the primary supply source would be bad for health.  By the way adding the electrolytes will also adjust the pH to within the range of the recommended US EPA range.  Really only end trace amounts of micronutrients and overall pH can be adjusted using calcium carbonate.  Hope that helps.