Water for Injection (WFI) is the single most important raw material in a sterile-liquids plant. In products like Sterile Water for Injection it is the product; in saline and respules it is more than 99% of the formulation. This article walks through a typical WFI system — the one Swanya operates in Baddi follows the same architecture.
Step 1: Purified Water
WFI starts as Purified Water. Feed water passes through ozone treatment, UV, a multigrade filter, a softener, reverse osmosis, electrodeionisation and a final UV stage before storage. You can explore an animated version of this train on our manufacturing page.
Step 2: Distillation
Purified Water is fed to a multi-column still. Pure steam supplies the first column; raw (plant) steam provides the heating energy. Vapour rises through successive columns, is condensed, and the condensate — now free of pyrogens and non-volatile impurities — is collected as WFI.
Step 3: Hot storage and the loop
Freshly generated WFI is held in a storage tank maintained at 80 °C and above. The tank breathes through a hydrophobic vent filter so that air entering as levels drop is sterile. From the tank, WFI is pumped continuously around a distribution loop to every point of use and back — hot, turbulent circulation is the primary defence against biofilm.
Step 4: Sampling and testing
A WFI loop is sampled routinely at generation, storage and user points. The four core tests are:
| Test | What it tells you |
|---|---|
| Conductivity | Ionic purity — confirms the still and EDI are performing |
| pH | Consistency of the water chemistry |
| Pyrogen / bacterial endotoxin test | The loop is free of Gram-negative bacterial debris |
| Microbial limit test | Viable counts remain within alert and action limits |
Results are trended, not just pass/failed, so that a slow drift is caught long before a limit is breached.
Capacity at Swanya
Swanya's water treatment plant handles 120 m³ per day — 100 m³ of soft water, 60 m³ of Purified Water and 48 m³ of WFI — enough to support batch sizes from 500 L to 2,500 L on the FFS lines. Read more about the site utilities or contact us to arrange a technical visit.
