Smell your tapwater. If it smells like chlorine, let it sit out uncovered overnight. If your locals used chlorine gas to kill the bacteria in the water, it should outgas overnight. If they use a solid form of chlorine, the smell will remain, and the water should likely be filtered.

Most tapwater is fine once properly ph'd, and can be used with no adverse effects. If there is no need to buy a R/O system or Britta filters, why do it? Why take the crap out of your water, just to have to replace the crap later? (CalMag Plus, for instance) Especially if unnecessary.

Ph'ing R/O water has no effect on ph pen probes. I've used them for years with my coral and saltwater fish tanks, which is a sensitive enviornment and does require R/O'd water.
You can not store the probes in direct light, or in tapwater, because the tapwater will form algae and the algae will skew results. (and gum-up the probe) An acid or a base is recommended for storage. (too harsh for bacteria and algae to get a foothold)

You can also look online for your local water conditions and ph. For instance, if in Phoenix, Google "Phoenix tap water quality" or "Phoenix municipal water quality report" or something along those lines.
Here's what my locals say about my well water online...(no, not Phoenix, lol)
"Characterization. The character of the groundwater varies from calcium-magnesium
bicarbonate to magnesium-calcium bicarbonate. The quality of
the groundwater is suitable for all beneficial uses. TDS concentrations range
from about 155 to 540 mg/L, with an average concentration of about 330
mg/L. Fluoride content ranges from 0.2 to 0.9 mg/L and averages about 0.4
mg/L. Boron content averages about 0.1 mg/L."

Mine averages near 380-390 mg/L. (saltwater aquarium test kit)

I have never used filtered water for my ladies, but I don't consider my water unusable, either.
Curious though...for those in soil, what does filtering your water do...specifically? (if you are filtering more than chlorine) As soon as you add the water to the medium, your TDS skyrockets, no?
Rusty Trichome Reviewed by Rusty Trichome on . Tap vs Filtered Water I have general question between the waters. I know filtered water is just what I said filtered, but I still have to ph it down to get it right level. Cant I just do it the same with tap water or does tap water have to much other chemicals that can damage the babies. :jointsmile: Rating: 5