Solutions by situation
An office — size against the right variables, not headcount alone
The problem
Office air and water purchases go wrong in two consistent ways, and both are sizing errors against the wrong variable.
Water systems get specified on headcount without a feed water analysis, so the plant either runs at its limit permanently or the membranes die early on water they were not designed for.
Air purifiers get bought by total floor area, which produces two large units for an office of eight closed cabins — seven of which are unaffected, because air does not move between rooms with the doors shut.
What this situation actually needs
Requirements first, in the order they matter. Note that several of these are not products.
Plant capacity matched to demand and duty cycle
A plant sized to run flat out has no headroom for membrane ageing.
Daily litres ÷ 60% of operating hours, rounded up to the next standard LPH
Pre-treatment specified from a water analysis
Feed quality determines the pre-treatment train and the achievable recovery.
Laboratory analysis before any quotation is accepted
Air capacity per enclosed zone
CADR does not distribute itself between closed rooms.
At least one unit per zone, total CADR at 4 air changes per hour
Reject water routing
At office scale the volume is substantial and easier to design for than to retrofit.
Reject plumbed to flushing or landscape use where feasible
Documented maintenance
In a workplace, nobody personally owns the filter schedule, so it slips.
AMC with itemised inclusions and recorded service dates
The specification
Written as a specification rather than a product name, deliberately. A specification survives a model being discontinued and can be taken to any shop; a product recommendation expires.
| Attribute | Target | Why |
|---|---|---|
| Water — sizing | ~3 litres per person per day; capacity = daily ÷ 60% of hours | Realistic office consumption including tea and coffee, with headroom |
| Water — specification basis | Laboratory water analysis before quotation | Any firm price without one is a guess |
| Air — unit count | One per enclosed zone, minimum | Air does not move between rooms with the doors closed |
| Air — total capacity | Treated volume × 4 ACH | A workable occupied-space target |
| Commercials | Five-year cost and cost per employee per year | The figures a finance team can benchmark against other facilities spend |
What to avoid
In every one of these situations there is a purchase that looks obviously right and is wrong.
Accepting a commercial RO quotation with no water analysis
Pre-treatment sizing depends entirely on feed quality, and it is the line item that varies most between quotations.
Buying air purifiers by total floor area
One large unit cannot serve four cabins with the doors shut, whatever its CADR. Count zones.
Evaluating on capex alone
Power, consumables, AMC and reject water typically exceed the purchase price over five years.
A 'comprehensive' AMC with no itemised inclusion list
The word means different things to different vendors, and the membrane is the item most often outside it.
Frequently asked questions
How do I size a water purifier for an office?
How many air purifiers does an office need?
What does office water and air purification cost per employee?
Budget bands are indicative Indian market ranges for planning, last reviewed 2026-08-08. Where this page recommends a test before a purchase, that ordering is deliberate — the specification depends on the result, and a recommendation made without one is a guess wearing a table.