Start with the lunch break
Count actual refills over several normal working days, including the day when most staff are in the office. Record bottle sizes and whether people choose cold, ambient or hot water.
A daily litre estimate hides a short queue immediately after lunch. Include visitors and cleaners if they use the same pantry.
Worked example: 18 bottles in 15 minutes
Hypothetical assumptions: 18 of 30 staff each refill 0.6 L during a 15-minute break. Demand is 18 × 0.6 = 10.8 L, averaging 0.72 L/min.
If usable cold storage begins at 5 L and verified cooling recovery is 8 L/hour at the relevant inlet and ambient temperatures, a simplified upper estimate is 5 + (8 × 15/60) = 7 L. That is 3.8 L short of the assumed demand.
Recovery may not be uniform, so ask for a draw-down demonstration rather than treating this estimate as a guarantee.
Check the queue separately
At an assumed dispensing rate of 1.2 L/min, filling those bottles takes nine minutes of tap time, before placing bottles and changing users. A large tank does not make a slow tap faster.
Total tank capacity may include hot or ambient storage: ask specifically for usable chilled output within an agreed temperature range.
Decide what would solve the actual problem
If cooling is the bottleneck, compare verified cold-water recovery. If the queue is the bottleneck, examine dispensing speed, staggered breaks or a second location.
Tankless equipment also has flow and heating or cooling limits. None of these dispensing features establishes what contaminants the filter removes; treatment must suit the supply.
Put it into practice
Your planning worksheet
A worked peak-demand calculation and pantry survey.
| Pantry survey | Record on site |
|---|---|
| Demand | Refills per 5-minute interval; bottle sizes; water temperature choice |
| Performance | Cold reserve, recovery test conditions and measured bottle-fill time |
| Layout | Queue route, sink access, power point and maintenance clearance |
| Continuity | Alternative drinking-water access during service |
Sources & context
- US CDC — About Choosing Home Water Filters
Supports matching treatment to the water supply and specific contaminants. Dispensing calculations and worksheets are GAGE planning examples, not CDC recommendations.
Sources checked 9 November 2026. Worksheets are editorial planning tools. Confirm site-specific requirements, current local guidance and the instructions for the equipment you use.
