Trichloroethylene in Well Water: The Public 0.005 mg/L Line

By SubcontractorHub Editorial Team·Published October 2026

Dealers meet trichloroethylene in well water on a lab sheet that also lists other solvents, or on a city report a customer brings to the kitchen table. The annual city packet is a consumer confidence report. This page is only the trichloroethylene row. The national primary rules apply to public water systems. They are not a private-well statute. How to order the jug is the well water testing guide. Which systems count as public is what a public water system is.

Trichloroethylene in Well Water on the Primary Table

The national primary drinking water regulations are legally enforceable primary standards and treatment techniques that apply to public water systems. In the organic block, trichloroethylene's MCLG cell is zero. The MCL is 0.005. The potential health effects listed are liver problems and an increased risk of cancer. The source cell says discharge from metal degreasing sites and other factories.

The table notes put those figures in milligrams per liter unless otherwise noted. The notes say milligrams per liter are equivalent to parts per million. 0.005 mg/L is therefore 0.005 ppm on that note. It is not a different standard. Moving the same digits to micrograms per liter uses the 1,000-to-1 scale on milligrams and micrograms. 0.005 mg/L is 5 µg/L on that scale. Write both labels if the lab used the smaller unit, so a later reader does not think 5 is a new limit.

An MCLG is a goal. An MCL is the enforceable public number. Zero in the goal cell is not a second MCL sitting under 0.005. The definitions of those two words are on MCL and MCLG.

The 0.005 Figure in the 2025 CFR

Section 141.61 of the 2025 Code of Federal Regulations prints maximum contaminant levels for volatile organic contaminants. Trichloroethylene, CAS 79-01-6, is 0.005 mg/L. Benzene, earlier on that table, is also 0.005 mg/L. The shared digits are not a shared row. Benzene has its own page, benzene in well water. Vinyl chloride on the same table is 0.002 mg/L, and that row is vinyl chloride in drinking 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 0.005 line onto a kitchen-tap jug still has to say the jug is not the public-system rule. The difference between a city report and a private well is private well water regulations.

What Is the Trichloroethylene Row Next To?

Tetrachloroethylene is the next solvent people mix with this name. It also prints 0.005 mg/L. Its source cell names factories and dry cleaners, and its CAS is 127-18-4. That row is tetrachloroethylene in well water. A lab sheet that says TCE is not a sheet that says PCE. Write the name the lab printed.

How to Read Trichloroethylene in Well Water on a Ticket

Five lines keep the public number from becoming a filter pitch. None of them is a removal percent.

1. The name on the lab row, and the CAS if the sheet has one. 79-01-6 is trichloroethylene.
2. The unit. If the sheet says µg/L, convert with the 1,000 scale before you compare it with 0.005 mg/L.
3. Whether the sample is a private well or a public system. The CFR sentence names community and non-transient non-community systems.
4. The source cell you are not using. Metal degreasing is this row. Gas tanks are benzene. Dry cleaners are tetrachloroethylene.
5. A blank where a removal percent would go. This page does not have one.

Other 0.005 Rows on the Same CFR Table

The 2025 volatile-organic table prints 0.005 mg/L more than once. Carbon tetrachloride, CAS 56-23-5, is 0.005. 1,2-Dichloroethane, CAS 107-06-2, is 0.005. Benzene, CAS 71-43-2, is 0.005. Tetrachloroethylene, CAS 127-18-4, is 0.005. Trichloroethylene is CAS 79-01-6. The shared digits are a column, not a chemical.

A dealer who highlights every 0.005 on the sheet and treats them as one solvent will propose one fix for four rows. Write the CAS next to the result. If the lab did not print a CAS, write the full name and leave the other 0.005 rows off this ticket. This page does not give those other rows a health cell or a source cell, because this fetch was for trichloroethylene.

What This Row Does Not Decide

The health-effects cell is EPA's description of long-term exposure above the MCL. It is not a diagnosis of the person who handed you the jug. Do not turn “liver problems” into advice about a customer's health. Send medical questions to a clinician.

The source cell is also not a verdict about this house. Discharge from metal degreasing sites is what the table lists. It does not prove a shop up the road caused this sample. A dealer who needs the system type, rather than the solvent row, should stay on the public-water-system page. A dealer who needs the whole primary list should use primary and secondary drinking water standards.

Frequently Asked Questions