I laughed at my brother's water filter conspiracy for 2 years until I saw the test strips myself
He kept saying our tap water in Phoenix was leaving stuff behind that the city reports don't mention, and when we ran a $30 lab kit last month the numbers came back way higher than the utility's posted results, so now I'm the one asking around, has anyone else tested their own water and gotten a totally different reading than the official report?
Honestly the lab kits you buy online can be all over the place and a lot of them aren't calibrated the same way the city's testing is. Utilities test at the plant and at points in the system, not at your kitchen faucet, so of course the numbers won't match up exactly, that doesn't mean they're hiding something. Also a $30 strip test is not the same as a certified lab test, those things can be off by a lot depending on how you use them. Phoenix water is known for being hard and having high TDS, that's not a secret, it's on their yearly report. If you really want to know, send a sample to a real lab that's certified, then compare that to the utility report, otherwise you're kinda comparing apples to oranges.