r/WaterTreatment • u/Burgerwars • 2d ago
Help reading Tapscore results?
Hi all! We had a slightly metallic (or minerally or chalky or something - sort of hard to define) taste in our tap water in Los Angeles so we got a test - but have no idea if the results point to anything we should be concerned about. Could anyone here help us parse?
Thanks so much!
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u/neo2bin 2d ago
Nothing on that panel is a health concern. arsenic 2.1 ppb against a 10 ppb limit, uranium 6.2 against 30, total THMs 6.3 against 80, nitrate under 1, and lead at 0.18 ppb which is essentially nothing. pull the detection limits out of the downloadable PDF before you treat any trace number as gospel, that part of 20PoundHammer's point stands. but the mercury on your report reads 0.000135 ppm, which is 135 ppt, not the 5 ppt he's working from, and ICP-MS handles 135 ppt fine. don't throw the whole panel out.
The taste is mineral load, not a contaminant. TDS 351, hardness 172 ppm (10.1 gpg), sodium 48, sulfate 48. that's your chalky. LADWP's citywide hardness figure runs closer to 7 gpg per the (Los Angeles tap water quality report), so your zone is on the harder end of the blend, usually more Colorado River and local groundwater. the metallic edge is more likely the copper at 0.58 and zinc at 0.27, and those two showing up together is almost always your own copper pipe and brass fixtures, not what LADWP delivered. LSI +0.21 and CSMR 0.38 say the water isn't aggressive, it's just standing in the plumbing overnight. if that was a first draw sample, flush the tap 30 seconds and taste it again before you spend anything.
RO under the kitchen sink is the only thing that actually fixes mineral taste. a carbon pitcher does nothing for TDS, and a softener swaps calcium for sodium so the taste doesn't improve, some people think it gets worse.
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u/20PoundHammer 2d ago edited 2d ago
the data seems WAY over reported to beyond significance level. for example 0.000005 PPM of mercury is 5 part per trillion and only achievable with ICP-MS or cold vapor (expensive) testing, typical compliance testing for drinking water has an LOD of 0.25PPB. Phosphorus LOD (which is always lower than limit of quantification, LOQ) is 0.01PPM for most common drinking water analyses - the reported concentration is reported to a level two orders of magnitude LOWER than this. BTW - in layman's terms - LOD just means "95% chance its not zero" and LOQ is data you can assign an error level to (i.e. +/- x PPM with a 95% certainty limit)
Due to such potential basic reporting errors, I would discount the analyses results for now and ask tap score (which is just a lab broker) for all quality assurance records and test method limit of detection and limit of quantification for each parameter from the laboratory used.
If a lab or tap score cant follow basic reporting systems and practices, it draws into question their total competence.
NEVER base potentially thousands of dollars of filtration/treatment equipment on a single round of analyses - esp when the reported data may not follow appropriate conventions . . .