Find out if your area has fluoride in the water.  I checked my area, and it listed all the water companies and what I had investigated was accurate! 

https://nccd.cdc.gov/DOH_MWF/Default/Default.aspx

Search your area your area, and if you discover fluoride in your water, consider getting the 6 Gallon Crown Berkey.  This kit comes with 2 Fluoride Filters which have a life span of 1,000 gallons.  Holds 6 gallons of purified water & Filters up to 6.5 gallons per hour. Designed for large groups of 35+ People

This powerful system purifies both treated water and untreated raw water from such sources as remote lakes, streams, stagnant ponds and water supplies in foreign countries, where regulations may be substandard at best. Perfect for outdoor activities and a must in hostile environments where electricity, water pressure or treated water may not be available. The Crown Berkey system removes pathogenic bacteria, cysts and parasites entirely and extracts harmful chemicals such as herbicides, pesticides, VOCs, organic solvents, radon 222 and trihalomethanes. It also reduces nitrates, nitrites and unhealthy minerals such as lead and mercury.