A pocket meter that tells you how many dissolved solids are in your water. Pull the cap off, dip the probe in the glass, read the number. It takes about five seconds.

Test your tap against your filter

Fill one glass from the kitchen tap and one from your RO faucet. Read both. Tap water around the DMV usually lands in the low hundreds of ppm. Water from a working RO membrane reads a small fraction of that. The difference between the two numbers is what your system removed.

Our installers run this check before and after every fit. Now you can run it whenever you want.

Know when your filters are done

RO membranes wear out slowly. As they do, the TDS of your filtered water climbs.

Take a reading the week your system goes in and write it down. Check again every month or two. When the number starts drifting up from that first reading, the membrane is near the end. You will know before the taste changes.

Three modes

The MODE button switches between:

TDS in ppm. Everything dissolved in the water, added up.
EC, electrical conductivity. Used in hydroponics and fish tanks.
Temperature, in °C or °F.

Buttons and build

ON/OFF HOLD freezes the reading so you can lift the meter out of the glass to look at it.
CLEAR drops the held reading and goes back to live.
The display is backlit, so it reads fine under a sink or in a dark basement.
A cap covers the probe between uses. It lives in a kitchen drawer without getting damaged.
Roughly the size and weight of a thick pen, about 50 g.

Other uses

Fish tanks, hydroponic reservoirs, pools and hot tubs, espresso setups where mineral content changes the shot, and water going into a humidifier or steam iron.

Specifications

Measures: TDS, EC, temperature
TDS range: 0 to 9,999 ppm
Accuracy: ±2%
Water temperature: 0 to 50 °C (32 to 122 °F)
Power: 2 x 1.5V LR44 button cells
Size: 155 mm x 25 mm (about 6.1" x 1")
Weight: about 50 g (1.8 oz)

What it does not measure

TDS is a total. It adds up the minerals, salts and metals dissolved in your water and gives you one figure. That makes it good for checking a filter is working and for tracking a membrane as it ages.

It will not detect lead, PFAS or disinfection by-products. Those are harmful at levels far below what any TDS meter can resolve. A low reading means low dissolved solids. It does not mean the water is clean.

If you want to know what is actually in your water, we test it for your address at no charge. Book a free water test.

Sanavia Digital TDS Meter