Aesthetic or operational characteristic

Total Dissolved Solids in water reports

Total dissolved solids, or TDS, is an aggregate measure of dissolved substances. It does not identify which substances are present or their individual concentrations.

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Federal scienceSource review:

This is a report-reading explainer. It is not a live advisory, household result, violation decision, or personal health assessment.

Report example:
1 entry from Silver City's 2025 report illustrates this term.
Type of report term:
Aesthetic or operational characteristic
Report-period evidence:
An annual-report row is evidence for the named report and source period, not a live monitoring result.
Current instructions:
Current status and instructions must come from the water provider, NMED, or another appropriate official source.

Meaning and report use

What the term means

USGS describes TDS as the sum of organic and inorganic substances dissolved in water. Common contributors can include calcium, magnesium, sodium, bicarbonate, sulfate, chloride, nitrate, silica, and other dissolved material.

Why it may appear in a report

Utilities may include TDS to summarize overall dissolved-mineral and dissolved-substance content and related aesthetic or operational context.

How it may be labeled

Other names you may see
Total Dissolved Solids; TDS
Label in Silver City's report
Total Dissolved Solids

Measurement context

How to read the unit and measure

Values remain attached to the labels, units, and table context printed by the official report.

Silver City prints TDS in PPM, while EPA prints its secondary value in mg/L. Both units are shown as printed. This page does not convert them to determine compliance.

Units used in reviewed sources

  • PPM as printed by the report
  • mg/L in the federal secondary table

Standards and reporting context

How this term fits the official framework

Primary standards, secondary standards, special monitoring, and customer-interest reporting are not interchangeable.

Secondary-standard context

EPA Part 143 lists 500 mg/L as a secondary level for TDS. It is not a federal primary health-based MCL. New Mexico incorporates Part 143, so this page does not independently determine state compliance.

Secondary context

Federal secondary maximum contaminant level

Source value
500 mg/L
Jurisdiction
U.S. EPA, 40 CFR Part 143
Classification
Secondary aesthetic and operational context, not a federal primary health-based MCL
New Mexico context
New Mexico incorporates Part 143. Check NMED for state application and official compliance information.

2025 report example

Silver City's 2025 report: Total Dissolved Solids

The values below use the report's original labels and units. They have not been converted or used to make a compliance finding.

Official report rowReport source retrieved:

Total Dissolved Solids

The Town of Silver City lists this value in the table titled “Substances of Frequent Interest to Customers.” The table does not give a testing year or regulatory criterion for this entry.

Public water system
Silver City Water System
Report
2025 Water Quality Report
Reported measurement
Average: 215
Range in report
Range: 190 - 238
Unit
PPM
Testing period in table
Not printed in table
Regulatory criterion in row
Not printed in row
Status in row
Not printed in row
Source table
Substances of Frequent Interest to Customers
Source page
4

The customer-interest table does not print a sample year or regulatory limit for this row.

Open the exact row in the Silver City report summary

Interpretation boundaries

What the row does not establish

These limits apply even when a result is printed clearly in an annual report.

What to verify next

  1. Read TDS as the combined amount of dissolved substances, using the report's printed value and unit.
  2. Do not infer individual constituent concentrations from the TDS total.
  3. Use NMED or the provider for current state application, status, and instructions.

Related report terms

Explore related report terms

These terms describe related water properties or measurements. Each page explains its own result from Silver City's report.

Water chemistry characteristic

Alkalinity

Alkalinity describes water's capacity to neutralize acids and bases and resist rapid pH change. It is a water property, not a contaminant identity or the same thing as pH.

Mineral or dissolved constituent

Calcium

Calcium is a dissolved mineral constituent that can contribute to hardness and total dissolved solids. Its individual report row is not the same as either aggregate measure.

Water chemistry characteristic

Hardness

Hardness is an aggregate water characteristic driven mainly by dissolved calcium and magnesium. It can affect soap performance and mineral scale without being a primary contaminant standard.

Official sources

Sources reviewed for this explainer

Every source records its publisher, retrieval and review date, version note, and the claims it supports.

Evidence

Official source path

Use official federal, state, utility, or report sources before treating a page as final.

Continue reading

Related interpretation paths

Use the separate directory, contaminant library, report-reading guide, and methodology according to the question you are trying to answer.

Contaminants directory

Use the separate contaminant library for primary standards, action levels, disinfectants, monitoring topics, and treatment measures.

View Contaminants directory

Data methodology

See how source records, annual-report evidence, limitations, and current-status boundaries are handled.

View Data methodology