Welcome to your UK source for the finest quality water testing instrumentation.

Our handheld TDS testers, in-line monitors, controllers and demonstration devices for reverse osmosis (RO) water filters and water purification systems are superior in construction and performance, yet made available at a very economic cost. HM Digital, Inc. are the only manufacturer of economical in-line dual TDS meters that measure total dissolved solids (TDS) levels of feed and product water lines simultaneously, an effective way to compare rejection rates and gauge reverse osmosis membrane, water filter and water purification performance.

With HM Digital water testing instruments, you'll know if your water is pure.

Please click on products to learn more about which TDS tester is right for you.

What is a TDS meter and what is TDS (Total Dissolved Solids)?