I started checking my tap water after noticing a faint taste change. A simple pH pen turned out to be the easiest first step. Here's what I do:
- Calibrate first. Use pH 7.00 buffer, then 4.00 if your meter supports two-point calibration. Skipping this is the most common reason for odd readings.
- Rinse the probe with distilled water, then dip it in a clean glass of tap water.
- Wait for the reading to settle, usually 10 to 30 seconds.
- Read it in context. UK drinking water usually falls between 6.5 and 9.5. A reading outside that range is worth re-testing, and worth raising with your water supplier.
- Store the probe moist in storage solution, never dry or in distilled water.
If you're comparing water before and after a filter, test both at the same temperature, because pH readings drift with temperature.
I wrote up more on choosing and using pH meters and home water filters at yinmik.co.uk.
