Preparation of Water for Injection (WFI)

Preparing Water for Injection (WFI) from raw water involves several purification and filtration steps to ensure it meets pharmacopeial standards (such as USP, EP, or JP). Here’s a general step-by-step process:

Pre-Treatment

This stage removes large contaminants and prepares the water for further purification.

• Raw Water Intake: Source water (e.g., municipal or well water) is collected.
• Filtration: Removes large particles, sand, and sediments using multimedia filters.
• Softening (if needed): Removes hardness (calcium & magnesium) using ion-exchange resins.
• Carbon Filtration: Removes chlorine, organic impurities, and odor.
• UV Treatment (optional): Kills bacteria and viruses.

Reverse Osmosis (RO) System

• Uses semi-permeable membranes to remove dissolved salts, bacteria, and organics.
• Typically, a two-pass RO system is used for higher purity.

Electrodeionization (EDI) or Ion Exchange

• Further removes dissolved ions and ensures low conductivity.
• Replaces traditional ion-exchange resin, avoiding the need for chemical regeneration.

Ultraviolet (UV) and Ultrafiltration (UF) Treatment

• UV Sterilization: Eliminates bacteria and breaks down organic compounds.
• Ultrafiltration: Removes endotoxins, pyrogens, and fine particulates.

Final Distillation (for WFI Production)

• Water is distilled using Multiple Effect Distillation (MED) or Vapor Compression (VC) distillers.
• This ensures complete removal of pyrogens, bacteria, and volatile impurities.

Storage & Distribution

• Stored in 316L stainless steel tanks with sanitary design.
• Kept at 80°C – 90°C(hot WFI) or 2°C – 8°C (cold WFI) to prevent microbial growth.
• Distributed through a loop system with sanitary pumps and UV sterilization.

Quality Testing

• Conductivity, TOC (Total Organic Carbon), endotoxins, and microbial load are tested to ensure compliance with USP/EP/JP standards.

This process ensures the WFI is ultra-pure, free of endotoxins, and suitable for pharmaceutical use, including injection formulations.

Read also:

• Pharmaceutical Water System
• Water Sampling Procedure in Pharmaceutical Industry
• Comparison Between Deionized Water, Reverse Osmosis Water and Distilled Water

Resource Person: Md. Razibul Islam