Guide · recordkeeping
How long to keep water system records
Short answer
- 5 years: microbiological (coliform) and turbidity results; variances after they expire.
- 10 years: chemical results and sanitary survey reports.
- 3 years: actions taken to correct violations (after the last action), and public notices.
- Your state sets retention for daily operating logs and residual readings, often 3 to 5 years.
Federal retention periods
| Record | Keep at least | Rule |
|---|---|---|
| Microbiological and turbidity analyses | 5 years | 141.33(a) |
| Chemical analyses | 10 years | 141.33(a) |
| Actions taken to correct violations | 3 years after the last action | 141.33(b) |
| Sanitary survey reports and related correspondence | 10 years after the survey | 141.33(c) |
| Variances and exemptions | 5 years after they expire | 141.33(d) |
| Public notices and certifications | 3 years after issue | 141.33(e) |
| Monitoring plans | As long as the analyses taken under them | 141.33(f) |
| Ground Water Rule corrective actions | 10 years | 141.405(b) |
| 4-log systems: state-specified minimum residual | 10 years | 141.405(b) |
| 4-log systems: lowest daily residual, and any failure to hold the minimum for over 4 hours | 5 years | 141.405(b) |
| Coliform assessments and corrective actions | 5 years after completion | 141.861(b) |
What a sample record must include
Lab reports can be kept as they are, or the data moved into tabular summaries, as long as each record keeps (40 CFR 141.33(a)):
- The date, place and time of sampling, and the name of the person who collected the sample
- What kind of sample it was: routine distribution, check sample, raw or process water, or special purpose
- The date of analysis
- The laboratory and the person responsible for the analysis
- The analytical technique or method
- The results
Records are kept on the system's premises or at a convenient location near them. For daily field readings like chlorine residual, your log sheet covers the same ground: see the chlorine residual log sheet.
State rules for operating logs
Daily operating logs and field readings are mostly governed by state rules. Examples from the states we cover:
| State | Retention |
|---|---|
| Texas |
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| Pennsylvania |
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| Ohio |
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| Indiana |
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| Michigan |
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| Missouri |
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| Florida |
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| Washington |
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| California |
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Keeping records safe
- Paper: file each month together, in order, somewhere dry. Scan or photograph filled-in sheets so one fire or flood doesn't take years of records.
- Electronic: make sure entries can't be silently changed, and keep a copy off the device. See electronic vs paper logbooks.
- Corrections: never destroy the original entry. See correcting logbook entries.
Questions
How long do I keep chlorine residual records?
It depends on your state and why you take them. Examples: Texas keeps distribution residual results 3 years, Washington 3 years, and Ohio operator logbooks 3 years. Under the federal Ground Water Rule, systems doing 4-log compliance monitoring keep their lowest daily residual records 5 years.
Can I keep records electronically?
Federal rules let lab reports be kept as they are or transferred to tabular summaries, as long as the required information is kept. Several states explicitly allow electronic records. Texas lets operating records be stored electronically, and Ohio allows computer logs that stamp date, time and author and prevent erasure. Confirm with your state.
Where do records have to be kept?
Federal rules say on the system's premises or at a convenient location near them. Some states require records at the facility and available for inspection at all times.
Sources
- 40 CFR 141.33 — Record maintenance
- 40 CFR 141.405 — Ground Water Rule reporting and recordkeeping
- 40 CFR 141.861 — Revised Total Coliform Rule reporting and recordkeeping
- 30 TAC §290.46 — Texas minimum acceptable operating practices (records, operators)
Last reviewed September 28, 2026. Rules change and states add their own; confirm with your state drinking water program.