Open Tools · Civil: water and wastewater
Clearbasin: free online water treatment sizing calculator
Clearbasin helps you size a preliminary drinking-water treatment train and check the arithmetic behind it. Enter a design flow and your own criteria for rapid mixing, flocculation, settling, filtration and disinfection contact segments, and the tool sizes volumes and areas and compares contact time with the targets you entered.
A water chemistry workspace partitions the carbonate system at a given pH, balances the ions you list, and reports LSI and RSI against a saturation pH you supply. A membrane workspace runs staged recovery and rejection water and salt balances with an ideal pressure screen. Design criteria and coefficients are always yours; nothing here is a regulatory table. Studies save as open JSON, results export as CSV, and the Verify page runs the reference checks in your browser.
What Clearbasin can do
- Size rapid mix, flocculation, settling basin and filter areas from your own criteria
- Compare disinfection CT with entered targets using exact arithmetic for the verdict
- Partition the carbonate system at a prescribed pH and read alkalinity
- Check charge balance and ionic strength for a list of ions
- Read LSI and RSI against an entered saturation pH
- Stage RO or NF recovery and rejection with water and salt ledgers and an ideal pressure screen
- Save and open JSON studies; export CSV, SVG and PNG; print a report
How we verify Clearbasin
Clearbasin is checked against 5 reference cases. Where a reference answer exists you can run every check yourself on the Verify page, and the Clearbasin user guide documents every feature and limitation.
The single case register is engine/verification/cases.ts, shared by the tests and the Verify page. Synthetic scalar checks use an exact-rational hand ledger generated independently of the engine. They cover four derivation families: treatment balances, carbonate/charge accounting, membrane salt/water ledgers and an ideal pressure screen. Scalar rows from one family are grouped; they are not presented as separate measured validations. Separate seeded tests solve small linear mass-action and balance systems against the engine over 240 states.
Clearbasin is part of Open Tools, the free engineering tools that run in your browser.
Professional use. Results are for education and preliminary design. They must be checked by a qualified professional, and they are not a substitute for code-compliant design or licensed engineering judgement.