Hisgadget via Amazon offers the Dr. Meter Pocket Water Tester
, model no. TDS-3C, for $16.99. Coupon code "5ZLYUWLO" cuts it to $11.99
. Plus, Prime members qualify for free shipping
. (Non-members can spend $35 to qualify for free shipping; otherwise, it adds $5.01.) That's the lowest total price we could find by $2. It can be used to assess the total dissolved solids value of water and features hold and auto-off functions.