Disinfection Byproducts in Drinking Water: The Four Public Rows

By SubcontractorHub Editorial Team·Published October 2026

Disinfection byproducts in drinking water are what this page sorts. It does not restate every chemical inside the two group sums. Those pages are total trihalomethanes in drinking water and haloacetic acids in drinking water. The disinfectant residuals that can form those byproducts are chloramine in drinking water.

Disinfection Byproducts in Drinking Water, Row by Row

The national primary page groups these contaminants under disinfection byproducts. The figures below are the cells on that table. Units are milligrams per liter unless noted. Milligrams per liter are equivalent to parts per million on the same footnote.

Every source cell in that block says byproduct of drinking water disinfection. That shared phrase is not a reason to add the four MCLs together. A report that prints one row does not imply the other three.

The Disinfectant Table Is Not This Block

Directly under the byproduct block, the same page lists disinfectants. Chloramines (as Cl2) have an MRDLG of 4 and an MRDL of 4.0. Chlorine (as Cl2) has the same pair, with a shorter health-effects cell. Chlorine dioxide (as ClO2) has an MRDLG of 0.8 and an MRDL of 0.8. Those are residual limits for the chemical that was added. They are not bromate, chlorite, HAA5, or TTHMs.

A customer who says “the water has chlorine” may be talking about a residual, a taste, or a byproduct line on a city report. Ask which document, and which row. The chloramine page keeps the residual story. This page only points at it so the two tables are not merged.

Public Systems, Not a Private-Well Statute

The national primary drinking water regulations are legally enforceable primary standards and treatment techniques that apply to public water systems. Copy that limit when you explain the number. A well owner can still want the same lab lines. The result is information about that sample. It is not, by itself, an MCL violation under the public rule.

How primary standards differ from the secondary aesthetic list is primary and secondary drinking water standards. These four rows are in the primary set. They are not on the secondary list of taste and color guidelines.

HAA5 and TTHMs Use an LRAA on Public Systems

40 CFR Part 141 Subpart V sets monitoring for maximum contaminant levels based on locational running annual averages for TTHM and HAA5. Quarterly systems calculate an LRAA at each monitoring location. A single sample at a private tap is not that math. Bromate and chlorite are in the byproduct block on the national table. This page does not claim the same LRAA sentence for those two rows, because the subpart V sentence fetched here names TTHM and HAA5.

If you need the four trihalomethane names, or the five haloacetic acid names, leave this page and open the matching article. Repeating those lists here would make a second copy of those guides. The job of this page is to stop a dealer from treating “byproducts” as one number.

Bromate and Chlorite Stay Short on Purpose

Bromate's public MCL is 0.010 mg/L, with an MCLG of zero, and the health-effects cell says increased risk of cancer. Chlorite's MCL is 1.0 mg/L, with an MCLG of 0.8, and the health-effects cell names anemia and, for infants and young children, nervous system effects. Both source cells match the other two rows: byproduct of drinking water disinfection.

Ozone can be part of a well-treatment conversation. The bromate caution already sits on ozone water treatment. This page does not add a new ozone dose, and it does not say when bromate will or will not form. If the lab printed bromate, write bromate and 0.010 as the public line you are comparing against. Do not file it under TTHM because both mention cancer risk.

What to Write Down Before a Quote

1. Name the row. Bromate, chlorite, HAA5, or TTHMs. “Byproducts” is not a row.
2. Copy the digits and the unit the sheet used. Convert with the thousand-to-one scale only when you also keep the original label. That scale is milligrams and micrograms.
3. Say whether the paper is one sample or a utility average. Do not invent an LRAA.
4. Say whether the address is a public system or a private well. The statute sentence depends on that.
5. Leave the residual, if you also have one, on the disinfectant line. Do not add it to the byproduct total.

What This Explainer Leaves Out

No removal percentage. No device ranking. No installed price. No claim that a softener, a sediment filter, or a UV lamp addresses this block. The well water testing guide plans a private-well panel. It does not, and this page does not, turn these four public rows into a mandatory well test.

A water treatment dealer can keep the four-row note on the customer record next to the PDF. The next visit should not have to guess which of the four numbers was discussed.

Name the Row Before You Name a Device

A homeowner sentence like “the water has chemicals from chlorine” can mean a residual, a TTHM line, an HAA5 line, bromate, or chlorite. Those are not interchangeable. Ask which document and which row before you name a filter.

The two long rows have their own pages, linked above. This explainer stops at the four figures and at the fact that the disinfectant table is separate. A residual of chlorine or chloramine is still not a byproduct result, even when the household uses one word for both.

What a Single Sample Can and Cannot Be

You can record the laboratory, the date, the sample point, the unit, and the digits. You can label the number as one sample. You cannot label it as a locational running annual average unless the utility report is the page in your hand.

Only the TTHM and HAA5 rows were given that average in the subpart fetched here. Bromate and chlorite stay on the national table. They do not inherit that average sentence from this fetch. Write the row name next to the digits so a later reader can see which rule you were looking at.

Leave the Inner Lists on Their Own Pages

This page does not rename the four trihalomethanes, and it does not rename the five haloacetic acids. Repeating those lists here would turn one explainer into a second copy of the long pages. Use this page to pick the row. Open the long page when the sheet names a chemical inside the sum.

How Do You Read Disinfection Byproducts in Drinking Water?

Start with the row name, then the public figure for that row, then whether the paper is a public-system average or one sample. Keep disinfectant residuals on their own table. Open the TTHM page or the HAA5 page only when the sheet names that sum. Do not add the four MCLs into a single score, and do not put a removal percent on the quote from this table alone.

Frequently Asked Questions