Water tools
UV dose-response from collimated beam counts and the dose for a target
Bench counts at a few doses give a straight line of log inactivation against dose. Its slope and intercept set the dose a target needs, and the standard reference bands tell you whether the surrogate stock behaved.
How it works
The zero-dose point is excluded from the fit. MS2 phage is the usual surrogate; a stock is accepted when every point lies inside the reference band bounded by
- organisms before and after exposure, per mL
- intercept of the fit
- slope of the fit, cm²/mJ
- UV dose, mJ/cm²
- target log inactivation
The regulatory credit doses already include dose-response uncertainty but not reactor, hydraulic or sensor uncertainty, which validation covers. Surrogates differ in resistance from the target organism: adenovirus needs six to nine times the coliform dose, Cryptosporidium a tenth to a third.
Related reading
These calculators use standard published formulas and are provided for preliminary engineering guidance. Confirm against measured data and vendor projections before design. Model your full water matrix in Nepti or post your project to compare provider proposals.