How to choose a water filter in 5 steps

For mains water, begin with your supplier’s latest report. Note what you want to improve: taste, smell or limescale. Measure hardness at your own tap before choosing a softener.

For well water, arrange chemical and microbiological testing before buying a treatment system. Clear, odourless water is not proof of safety. Tell the laboratory about your source, intended use and existing filters.

Write down the number of users, installation location, current equipment, flow rate and pressure.

Use a WODARO drop test to measure total hardness before choosing a softener and to check its performance afterwards. Follow the sample volume, colour-change endpoint and unit conversion specified in the kit instructions.

Use the WODARO 7-in-1 meter for pH, EC and TDS, with additional ORP, salinity, relative density and temperature measurements. Prepare and calibrate it as instructed, rinse the probe and wait for a stable reading. TDS does not measure hardness or establish water safety.

Ask a laboratory about iron, manganese, ammonium, nitrate, nitrite, pH, hardness, turbidity and microbiological testing, including E. coli and intestinal enterococci. Agree on the sampling point, containers and transport before collecting water. For selecting treatment, a sample before the existing filter is usually needed.

WODARO drop test

View tester →

WODARO 7-in-1 meter

View tester →

Compare the same parameter in the same unit. For example, 0.30 mg/l of iron equals 300 µg/l. For hardness, 20 °dH is approximately 356 mg CaCO₃/l; use the converter when necessary.

The infographic uses reference values for Poland. Green applies to one parameter only; it does not confirm overall water safety. Bars are schematic and do not indicate risk magnitude.

If bacteria are detected or nitrate/nitrite limits are exceeded, use a safe drinking-water source and contact the relevant public health authority. Boiling does not remove nitrate.

The infographic shows 4 basic parameters. The complete table of 9 parameters and filter guidance is available in the Polish guide.

Full table of 9 parameters in Polish →

Prepare your report, including values, units, date and sampling point. Open the advisor in results mode, choose your water source and answer the questions about intended use.

Enter available measurements in the units shown beside the fields. Do not replace missing measurements with zero. Check the recommended treatment direction and open the suggested product pages.

If results are incomplete or several parameters need treatment, complete the tests or ask an advisor to confirm the configuration.

Before purchasing, check the manufacturer’s permitted input-water parameters, capacity, flow rate, pressure, connections and space for installation and servicing. Some systems need drainage or power.

Compare running costs, cartridge availability, replacement intervals and warranty conditions. Confirm complex whole-house installations with an advisor.

After installation, check the result: measure hardness with a tester and repeat laboratory tests where needed. Maintain the device according to its instructions.