This article is Chapter 4 of Valutek’s Technical Paper Series:
Standard Operating Procedures for Controlled Environments
Cleanrooms demand a meticulously defined and executed cleaning regimen. SOPs for cleaning and sanitizing controlled environments are essential to ensure the continuous removal of viable and non-viable particulates while maintaining regulatory compliance and operational consistency.
By the end of this chapter, readers will understand how to:
Define cleaning frequencies and task sequences based on ISO classification
Select compatible cleanroom wipers, mops, and chemistries for various surfaces
Write clear, step-by-step SOPs that standardize procedures and minimize contamination risks
Incorporate validation, auditing, and visual inspection techniques to verify outcomes
“Having documented and scheduled cleaning that is conducted according to the SOP maintains the integrity of the controlled environment and decreases the risk of product contamination.”
Cleaning SOPs must account for surface-specific and time-based frequencies. For example:
Daily: Work surfaces and equipment
Weekly: Floors, tacky mats
Monthly: Walls, ceilings
Quarterly/Semi-Annually: Full facility deep cleaning
These tasks must follow a top-to-bottom and clean-to-dirty progression, always ending at the exit. SOPs should specify the direction of wiping/mopping and techniques such as pull-lift and crisscross patterns.
Only cleanroom-compatible tools and solutions should be used. SOPs must identify approved:
Wiper materials (e.g., polyester, microfiber, poly-cellulose)
Mops and swabs (pre-saturated or dry with spray)
Cleaning agents like 70% IPA, sterile DI water, or application-specific disinfectants
Material compatibility with surfaces and chemistries must be documented to prevent corrosion or residue buildup.
Effective SOPs include:
Specific stroke directions and overlap percentages
Identification of zones and cleaning order
Chemical handling protocols and safety requirements
Instructions for removing gross contamination before disinfection
Validation includes visual inspections, particle probes, white/UV light examination, and viable residue testing via swabs.
“The SOP should specify the exact cleaning sequences, down to the stroke and direction of mopping and wiping.”
SOPs should establish task-specific cleaning frequencies and validated techniques
Only approved materials and chemistries should be used to avoid surface degradation
Cleaning steps must be ordered and directional, ensuring clean-to-dirty progression
SOPs should include auditable processes with defined checkpoints and change history
Continue deepening your understanding of SOPs for controlled environments:
Chapter 1: Introduction to Writing Internal SOPs for Controlled Environments
Chapter 2: Optimizing Cleanroom Operations – SOPs for Gowning Protocols
Chapter 3: SOPs for Cleanroom Operator Requirements and Training