How the estimates work
Showers = flow × minutes/shower × showers/resident/day × residents. Tap use = flow × running minutes/resident/day × residents. Toilets = litres/flush × flushes/resident/day × residents.
Laundry L/day = litres/cycle × hostel cycles/week ÷ 7Shared laundry is never multiplied by residents. Per-resident use includes an equal share of laundry. A month is 30 days; monthly figures use full precision before rounding. Displayed rows may differ slightly from totals because of rounding.
Reference inputs: 50 residents; 1 shower/day at 8 minutes; 10 tap minutes/day; 5 flushes/day; 25 shared laundry cycles/week. Standard model ratings give 8,364 L/day; all six changes give 5,143 L/day.
A useful starting point, not a meter reading
All figures are estimates. Occupancy, habits, pressure, machine programs, and load sizes vary. The model excludes leaks, cooking, drinking, cleaning, and outdoor use. Use measured fixture ratings when available.
EPA values use rounded US gallon conversions. The 5.7 L/min faucet maximum applies to private lavatories; shared public-use faucets may have different requirements. This is not a compliance assessment.
Scenario targets: showers ≤5 min, showerheads ≤7.6 L/min, aerators ≤3.8 L/min (chosen target), toilets ≤4.8 L/flush, washers ≤50 L/cycle, and 20% fewer laundry cycles. Washer values of 60/50 L are model assumptions; ENERGY STAR reports other typical volumes. Check your machine label.
Changes combine multiplicatively where they overlap. Recommendations rank measures individually against the same baseline. All calculation runs in your browser; source links need internet, but the downloaded calculator works offline.