Xylenes in Well Water: The Public 10 mg/L Line

By SubcontractorHub Editorial Team·Published October 2026

A solvent panel can list several petroleum names on one page. The digit next to total xylenes is not the digit next to toluene, and it is not the digit next to ethylbenzene. Dealers who sell treatment still have to say which public line they are reading. SubcontractorHub is software for the customer record. This page is the row. It is not a treatment design.

The Public 10 mg/L Line for Xylenes in Well Water

The national primary drinking water regulations are legally enforceable primary standards and treatment techniques that apply to public water systems. In the organic block, xylenes (total) show an MCLG of 10 and an MCL of 10. The potential health effects cell says nervous system damage. The source cell says discharge from petroleum factories and discharge from chemical factories.

Footnote 2 says units are in milligrams per liter unless otherwise noted, and that milligrams per liter are equivalent to parts per million. 10 mg/L is therefore 10 ppm on that note. It is not a second standard hiding under a different name. Moving the same digits to micrograms per liter uses the 1,000-to-1 scale on milligrams and micrograms. 10 mg/L is 10,000 µg/L on that scale. Write both labels if the lab used the smaller unit, so a later reader does not think 10,000 is a new limit.

An MCLG is a goal. An MCL is the enforceable public number. On this row the two cells print the same digit. That match is not true of every neighbor. The definitions of those two words are on MCL and MCLG. A goal is not a fine, and a matching pair is still one line.

The 10 mg/L Figure in the 2025 CFR

Section 141.61 of the 2025 Code of Federal Regulations, in the XML dated 2025-07-01, prints maximum contaminant levels for volatile organic contaminants. Xylenes (total), CAS 1330-20-7, are 10 mg/L. Toluene, earlier on that table, is 1 mg/L. Those are not one number. The toluene row has its own page, toluene in well water.

Paragraph (a) says those volatile-organic levels apply to community and non-transient, non-community water systems. A private well is not named in that sentence. A dealer who copies the 10 mg/L line onto a kitchen-tap jug still has to say the jug is not the public-system rule. The difference between a city system and a private well is what is a public water system.

Xylenes in Well Water Are Not the 0.7 Row

Ethylbenzene prints 0.7 mg/L on the same national table, with a source cell that says petroleum refineries. That is a different chemical and a different source sentence. The page for that digit is ethylbenzene in well water. Benzene, at 0.005 mg/L, is benzene in well water. Do not paste a refinery sentence or a gas-storage sentence onto the xylenes row because the words sound related.

Carbon tetrachloride is 0.005 mg/L, on carbon tetrachloride in well water. Adding the neighbors together is not the rule this page fetched. If the lab wrote xylenes, write xylenes. If the lab wrote a single isomer the table did not split out, say what the sheet printed and do not invent a separate public MCL for that isomer.

What the Note Holds, and What It Does Not

The table above is the note. It is not a quote, and it is not a removal design. A customer who wants a price still needs a test, a model, and a scope. Those live on the job. This page only stops the wrong digit from landing in the scope.

Two Names for One CAS Number

Table 1 of the CFR section says Xylenes (total). Table 2, the best-available-technology list, says Xylene, still at CAS 1330-20-7. A dealer who treats those headings as two contaminants will quote two limits that the rule did not print. Write both headings on the work order if the office is comparing the tables, and write one CAS number.

The national page uses Xylenes (total) and prints 10 and 10. That is the pair to read first. The CFR confirms the MCL. Neither page, on the fetch used here, split m-xylene, o-xylene, and p-xylene into three public MCLs. Do not build three limits out of one total.

What the BAT Marks Do Not Promise

Table 2 marks granular activated carbon and packed tower aeration for the xylene row. The oxidation column is empty. Those marks identify a technology the rule names for compliance with the MCL. They do not say what percent a cartridge in a basement will remove, and they do not say the empty oxidation cell is a ban you can explain as a product feature.

A city plant and a point-of-entry tank are not the same machine. If you sell carbon, say you sell carbon. Do not say the X in the GAC column is a guarantee on this well. No removal percentage was fetched for this row, so none is printed here.

What Should the Xylenes in Well Water Note Say?

Five lines keep the next visit from borrowing a neighbor. If a line does not apply, mark it skipped. A blank line looks the same as a step you forgot.

1. The chemical name as the lab printed it, plus CAS 1330-20-7 if the sheet has a CAS column.
2. The result and the unit. If the unit is µg/L, show the mg/L equivalent on the 1,000 scale before anyone compares it with 10.
3. The public pair you compared it with: MCLG 10 mg/L and MCL 10 mg/L, named as the national table.
4. Whether the sample is a private well or a public system. Paragraph (a) names community and non-transient, non-community systems.
5. What you did not claim: no removal percent, no installed price, and no statement that 10 mg/L is toluene's 1 mg/L.

Where the Row Sits on the Job

The lab sheet belongs with the customer, the address, and the date of the sample. A price for equipment is a later page, after someone has read this row and the rows next to it. Mixing the 10 mg/L line into a softener quote because the water “smells like solvent” skips the chemical name.

How a dealer reads a full panel, including which tests were actually run, is the well water testing guide. The software that holds the customer file is water treatment contractor software. This article does not size a filter and does not tell a household the water is safe to drink.

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