What are deviation thresholds and targets?
When you take a reading on a brew sheet — say a gravity, pH, or temperature — Breww can compare it against the value you expected. Targets are the value or range you were aiming for, and deviation thresholds define how far the actual reading can drift before Breww flags it.
This gives you three useful things on the brew day:
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A clear target line on each reading so the brewer knows what they should be hitting.
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Visual warnings on the brew sheet when a reading falls outside the warning or out-of-spec band.
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An Alerts tab on the production dashboard that surfaces any out-of-range readings across recent batches in one place.
Targets are set per recipe action. Deviation thresholds are set centrally per input variable or calculated variable, with optional per-action overrides for the rare cases where a specific reading needs to behave differently.
Thresholds are only used to flag readings — they never block a brew day or stop you saving a recipe. A reading outside the threshold is still recorded normally; Breww just highlights it so it can be reviewed.
How targets and thresholds fit together
Think of each reading as a number line:
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The target is the value (typically the midpoint of a range) the brewer is aiming for.
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A warning band sits on either side of the target — readings here are still acceptable but worth noticing.
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An out-of-spec band sits beyond the warning band — readings here are flagged on the dashboard's Alerts tab.
Thresholds are expressed as fixed offsets (e.g. ±0.5 °C) of the target. Breww renders this as a coloured bar next to each reading on the brew sheet so the brewer can see at a glance whether they are on target.
Setting targets on a recipe action
Targets are configured on individual reading actions inside your recipe. Open the recipe, edit the reading action, and enter the value you expect to hit.
For most reading types you can enter either:
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A single target value (e.g.
5.2 pH), or -
A target range with start and end values (e.g.
5.0–5.4 pH).For temperature, gravity, pH, weight and volume readings you also choose the unit. For time readings, the target is a time.
If you don't enter a target, the reading still works on the brew sheet — there's just no target line or threshold bar drawn next to it.
System defaults vs. your own defaults
Breww ships with a sensible set of system default deviation thresholds for most measurement types (temperature, gravity, pH, volume, weight, time). These are what you'll see on every variable until you decide to change them.
You can override the defaults for any input variable or calculated variable. Your overrides apply to every recipe in your account that uses that variable.
To manage these:
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Go to
Production->View->Recipes. -
Click
Settings & options->Deviation thresholds. -
You'll see two tables: Input variables and Calculated variables, each listing every variable on your account, its measurement type, and the thresholds that currently apply.
For each variable, you can:
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Click the edit (pen) icon to open a form and set custom thresholds.
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Click the revert icon (where shown) to discard your override and fall back to the system default.
A variable that's still using the system default doesn't have your own override, so the revert button is hidden for that variable until you save an override.
Editing a variable's thresholds
In the edit form, you set:
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Unit — the measurement unit your thresholds are expressed in (e.g.
°C,SG,pH). The dropdown is restricted to units valid for the variable's measurement type. -
Warning band and out-of-spec band — each as either an absolute offset (e.g.
± 0.5) or as a percentage of the target (e.g.± 5%). -
Whether the bands are symmetric (the same on both sides of the target) or different above and below.
A live preview at the bottom of the modal shows you exactly how the thresholds will render on the brew sheet, using a sample target value.
Thresholds are stored in whichever unit you pick, but Breww will convert them for display so they always make sense alongside the reading's actual unit. For example, a threshold defined in °C will still render correctly when a brew sheet shows the reading in °F.
Per-action threshold overrides
Most of the time, thresholds at the variable level are exactly what you want — set them once, and every reading/recipe using that variable picks them up automatically.
Occasionally, though, a single recipe action needs different thresholds. (For example, the same gravity input variable might be tighter at end-of-fermentation than at the start.) For these cases, every recipe reading and calculated-variable action has a Deviation thresholds source option:
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Use linked variable deviation thresholds (default) — the action inherits whatever thresholds are configured on its linked input or calculated variable.
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Override thresholds — the action defines its own thresholds, ignoring the variable's.
When you pick Override, the same threshold editor used on the central settings page appears inline on the action form, and a live preview shows how it will render with the action's target value.
If a recipe action references a variable that doesn't have any thresholds yet (and no per-action override has been set), Breww will show an inline warning on the action so you know the reading won't have a threshold preview until you configure them.
Deviation thresholds on the brew sheet
When a brewer opens the brew sheet for a batch, every reading action that has a target shows the target value and, if thresholds are configured, the coloured threshold bar.
As the brewer enters their actual reading, a marker appears on the bar showing where the reading falls — green inside the target zone, amber inside the warning band, or red if it has gone out of spec.
The same target/threshold information is included on the PDF brew sheet so it's visible if you print the brew sheet for a paper-based brew day.
The Alerts tab on the production dashboard
When a reading goes out of spec, Breww surfaces it on the Alerts tab of the production dashboard so it doesn't get lost mid-brew day.
The Alerts tab lists every brew sheet reading whose value falls in the out-of-spec band, across batches at the current site, within a configurable lookback window. Each row shows:
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The batch the reading belongs to.
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The stage and turn the reading was taken on (for multi-turn batches).
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The input variable the reading is linked to.
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A reading vs. threshold preview showing the marker position on the threshold bar.
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Who recorded the reading and when.
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Quick-access buttons to jump to the batch or its brewing page.
A small red badge on the Alerts tab itself shows the number of outstanding alerts so the team can spot them at a glance.
The Alerts tab currently surfaces input variable readings only. Calculated variable alerts and batch (fermentation readings) are planned for a future release.
Adjusting the lookback window
By default, the Alerts tab looks back two days (today + yesterday). You can change this:
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Go to
Settings->Production settings->General production settings. -
Scroll to the Alerts section.
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Set Days to look back for production alerts:
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0= today only -
1= today and yesterday -
2= today plus the previous two days, and so on.
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Save the form.
A shortcut button on the Alerts tab itself (
Adjust lookback period) takes you straight to this setting.
If you raise the lookback window high enough that the number of candidate readings exceeds Breww's internal cap, the tab will show a notice telling you so. In that case, drop the lookback period back down to see the most recent alerts again.
Tips for getting the most out of thresholds
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Start with system defaults. They cover most measurement types reasonably; only override with your own values when you have a clear reason.
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Use brewery-level thresholds for general-purpose variables (e.g. mash pH, OG). Use per-action overrides sparingly, for specific actions where a different tolerance genuinely applies.
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Always set a target on important readings. Without a target, no threshold bar can be drawn — even if thresholds are configured on the variable.
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Tighten thresholds gradually. Setting them too narrow at first will produce a lot of dashboard alerts; loosen until the alerts you do see are genuinely worth investigating.
