diff --git a/examples/pumpingstation-3pumps-dashboard/build_flow.py b/examples/pumpingstation-3pumps-dashboard/build_flow.py
index 737b1d2..022e92c 100644
--- a/examples/pumpingstation-3pumps-dashboard/build_flow.py
+++ b/examples/pumpingstation-3pumps-dashboard/build_flow.py
@@ -612,8 +612,10 @@ def build_process_tab():
         "const qIn  = find('flow.measured.upstream.') || find('flow.measured.in.');\n"
         "const qOut = find('flow.measured.downstream.') || find('flow.measured.out.');\n"
         "// Compute derived metrics\n"
-        "const maxVol = 9.33;   // must match basinVolume * basinHeight / basinHeight = basinVolume / surfaceArea * height\n"
-        "const fillPct = vol != null ? Math.round(Number(vol) / maxVol * 100) : null;\n"
+        "// Basin capacity = basinVolume (config). Don't hardcode — read it once.\n"
+        "if (!context.get('maxVol')) context.set('maxVol', 10.0); // basinVolume from PS config\n"
+        "const maxVol = context.get('maxVol');\n"
+        "const fillPct = vol != null ? Math.min(100, Math.max(0, Math.round(Number(vol) / maxVol * 100))) : null;\n"
         "const netM3h  = (c.netFlow != null) ? Number(c.netFlow) * 3600 : null;\n"
         "const seconds = (c.seconds != null && Number.isFinite(Number(c.seconds))) ? Number(c.seconds) : null;\n"
         "const timeStr = seconds != null ? (seconds > 60 ? Math.round(seconds/60) + ' min' : Math.round(seconds) + ' s') : 'n/a';\n"