You MUST at  LEAST Test for Chlorine in Your Drinking Water!   
Why?

Water Test Meters

Three (3) Function Water Tester/Meter: pH/ORP/Temperature

$99.95

$99.95

Digital pH Controller + Electrodes

$214.95

$214.95

Six (6) Function Pen-Style Water Tester/Meter

$219.95

$219.95

Digital pH + ORP (2 in 1) Controller with Electrodes + CO2/O3 Relay

$219.95

$219.95