Tool release 1.1 — 6 October 2026. This page defines the calculations, comparison rules, source scope and review status for the flow observation calculator and backwash checker.
What these tools calculate
F2 converts volume and elapsed seconds to an interval-average observed flow. F1 compares a recorded supply against user-entered exact-system requirements. Neither certifies well yield, sustained delivery, contaminants, treatment performance or an installation. The tools do not independently verify any source reference or checked condition.
Equations and units
| Calculation | Rule | Boundary |
|---|---|---|
| Observed US GPM | US gallons ÷ seconds × 60 | Volume and seconds must be finite and positive. |
| Observed litres/minute | Litres ÷ seconds × 60 | One US gallon = 3.785411784 litres; Imperial gallons are not accepted. |
| Flow difference | Recorded supply US GPM − entered minimum US GPM | A zero difference means equality, not reserve capacity. |
| Minimum-pressure difference | Observed minimum flowing inlet psi − documented minimum inlet psi | Does not calculate pressure loss or maximum-pressure suitability. |
| Single constant-flow cycle volume | Entered required US GPM × entered cycle minutes | Excludes other cycles, concurrent demand and storage analysis. |
Conversion source: NIST Handbook 130 (2023), capacity conversion table. Calculations retain numeric precision internally; displayed values usually round to two decimals. Very small or large results use scientific notation. Display rounding never changes the threshold comparison.
Comparison and uncertainty rules
The comparison remains unresolved when flow, pressure, duration, location or the source reference is missing or invalid; when observed duration is shorter than the documented cycle; or when configuration, comparable conditions, maintained supply, temperature applicability or drainage is unconfirmed. An unresolved condition takes precedence over a favorable numerical difference.
When those records are complete, a lower supply flow or lower minimum pressure produces “below an entered hydraulic requirement.” Otherwise the entered comparison is met, with installation explicitly unapproved. The tool has no preset minimum pressures, default durations or universal reserve factor. Maximum pressure and all other manual conditions remain separate.
Primary source register
| Source checked 6 October 2026 | What it supports | What we do not infer |
|---|---|---|
| Pentair Fleck 5600 filter time-clock specifications | Maximum component backwash capacity stated at a pressure drop. | A homeowner supply measurement or a universal system requirement. |
| Pentair Fleck 2510 filter time-clock specifications | A different valve rating under the stated pressure-loss condition. | A filter recommendation based on valve capacity alone. |
| Amtrol MC10188 (04/24), printed pages 6–7 | Model-specific nominal volumes, drawdown tables and separate VFD sizing context. | Usable storage or a pressure setting for an unmeasured installation. |
| Watch-Water Katalox Light operation manual #140513KL-OPM, pages 1–2; distributor-hosted copy | Media documentation distinguishes initial conditioning and routine cycles. | A current assembled-system preset or endorsement of the document’s health claims. |
| NGWA Well Owner’s Guide | Background on well-system components and professional assessment. | A validation of this site’s measurement procedure. |
Additional source example: Genesis Katalox manual, printed pages 5 and 8. Its model table and differently stated pressure conditions are discussed on F1; supplier clarification remains necessary.
Where assembled-system instructions and a media document appear to disagree, do not blend them into an average requirement. Obtain configuration-specific clarification from the supplier and retain the written response. Source check dates describe our review of documentation, not a manufacturer revision date.
Software verification and technical review
Release verification covers unit conversion, finite positive values, threshold equality, flow and pressure mismatches, missing records, shorter observation duration, unconfirmed conditions, cycle-volume arithmetic and changed-input behavior. Browser checks cover the live forms, readable output, local downloads and responsive layout. These are software checks, not field measurements or professional installation validation.
Independent professional review of a hands-on testing or installation procedure has not been completed. No contaminant-removal testing or engineering credentials are claimed. The publisher profile identifies the actual publishing role; qualified technical reviewers will be credited only when their review is completed.
Input handling
The calculators run in your browser. They do not send their entered observations to our server. Optional text downloads and printing use your device. This statement applies to calculator entries; it does not describe every hosting, security or website-access log. Do not enter private laboratory identifiers or household contact information.
Release history
| Release | Change |
|---|---|
| 1.1 · 6 October 2026 | Added explicit inlet-pressure and duration records, configuration confirmation, numerical pressure/duration checks, local text exports, clearer unit handling and invalidation of stale results after input changes. Expanded the supporting guides and source scope. |
| 1.0 · 6 October 2026 | Initial volume/time calculator and manually entered backwash comparison. |