Sanitary design is getting more attention than it has in years, and I think the reason is simple. In my experience, a recurring root cause behind contamination problems is equipment and rooms that cannot be cleaned reliably. You can write the best sanitation SOP in the industry, but if the machine has a hollow roller, a ledge where powder settles, or a weld that traps product, the SOP is fighting the equipment every shift.
This article walks through what sanitary design means in practice, which regulations actually say something about it, how to evaluate equipment before you buy it, and where I see companies get stuck.
What Is Sanitary Design?
Sanitary design is the practice of building facilities and selecting or fabricating equipment so that they can be cleaned and, where needed, sanitized effectively and consistently, and so that they do not themselves become a source of contamination. It covers surfaces, geometry, materials, airflow, drainage, and access for cleaning and inspection.
The phrase comes most directly from the food industry, where groups such as the 3-A Sanitary Standards organization and the European Hygienic Engineering and Design Group (EHEDG) publish detailed design criteria. But the idea applies across every FDA-regulated sector: drugs, dietary supplements, OTC products, cosmetics, and food. The regulations differ in wording. The physics of a crevice that holds residue does not.
Why Is Sanitary Design Getting So Much Attention Right Now?
A few things are pushing it forward at the same time.
First, FDA's food safety rules under 21 CFR Part 117 have been in force long enough that inspectors are looking past paperwork and into how equipment is built and maintained. The rule's subpart B requires that equipment and utensils be designed, constructed, and maintained to be adequately cleanable (21 CFR 117.40).
Second, recall activity tied to environmental pathogens and cross-contact keeps reminding firms that a cleaning program is only as good as the surfaces it has to clean. In my experience, allergen cross-contact and Salmonella problems frequently involve equipment that was hard to disassemble or impossible to see inside. Check the warning letters and Form FDA 483s for firms in your own sector to see how often equipment cleanability is cited.
Third, any firm adding or replacing a line is making design decisions now. Fixing a hygienic design problem on a drawing costs very little. Fixing it after installation and qualification means rework, requalification, and downtime, and in my experience it often does not get fixed fully.
What Do the Regulations Actually Require?
Sanitary design is rarely labeled as such in US regulations. The requirements live in the equipment and facility provisions of each part. The table below compares the main ones.
| Sector | Regulation | Relevant clause | What it says about design |
|---|---|---|---|
| Finished pharmaceuticals | 21 CFR Part 211 | 211.63 | Equipment must be of appropriate design, adequate size, and suitably located to facilitate operations and cleaning and maintenance |
| Finished pharmaceuticals | 21 CFR Part 211 | 211.65(a) | Equipment surfaces must not be reactive, additive, or absorptive so as to alter the drug's quality |
| Finished pharmaceuticals | 21 CFR Part 211 | 211.67 | Equipment must be cleaned, maintained, and sanitized at appropriate intervals, with written procedures |
| Dietary supplements | 21 CFR Part 111 | 111.20 | Plant and grounds must be designed and constructed to permit cleaning and prevent contamination |
| Dietary supplements | 21 CFR Part 111 | 111.27 | Equipment and utensils must be of appropriate design and construction, cleanable, and maintained to protect against contamination |
| Human food | 21 CFR Part 117 | 117.40 | Equipment and utensils must be designed, constructed, and maintained to be adequately cleanable and properly maintained to protect against allergen cross-contact and contamination |
| Human food | 21 CFR Part 117 | 117.20 | Plant and grounds: construction and design must permit adequate cleaning and prevent contamination |
| Cosmetics | MoCRA (FD&C Act section 606) | GMP rulemaking provision | Section 606 directs FDA to establish cosmetic GMP regulations. That rule has not been finalized, so there is no binding design text yet and expectations are drawn from FDA guidance and industry standards |
Two things stand out when you read these side by side. The drug rule is written around quality of the product, so the emphasis is on surface reactivity and cleanability. The food rule adds explicit language on allergen cross-contact. And in cosmetics, the regulatory text is still catching up, which is why I tell cosmetic manufacturers to use the food and drug expectations as a practical benchmark.
What Are the Core Principles of Sanitary Design?
Different standards phrase them differently, but the same ideas show up everywhere. They work well as questions you can ask while standing in front of a piece of equipment.
Can You Reach and See Every Product-Contact Surface?
If a surface cannot be seen, it cannot be verified clean. Equipment should disassemble without specialty tools where possible, and inspection ports, hinged guards, and removable panels should make the inside accessible. A cleaning procedure that says "visually inspect" for a surface nobody can see is a procedure that will be signed off without being done.
Are the Surfaces Smooth, Non-Porous, and Compatible?
Stainless steel (commonly 316L in pharmaceutical settings) is popular because it is durable, non-reactive, and tolerant of cleaning chemicals. Surface finish matters as much as the alloy. Welds should be continuous, ground smooth, and free of pits. Threads, exposed bolt heads, and rough castings in the product zone are all harborage points. Gaskets and seals need to be compatible with both the product and the cleaning agents, because a degraded gasket sheds particles and holds residue.
Does the Equipment Drain and Self-Clean Where It Should?
Horizontal surfaces collect product, and low points collect liquid. Sloped surfaces, rounded internal corners, and proper drain placement keep wash water and residue moving out of the system instead of sitting. Internal radii are a classic example: a sharp 90-degree corner in a tank or hopper is much harder to clean than a rounded one, and in my experience the sharp corner is where residue most often turns up in swabs.
Are There Hollow Areas, Dead Legs, or Crevices?
Hollow rollers, unsealed tubes, and hollow frame members can trap moisture and product and let microbes grow where nobody looks. Piping dead legs are a related issue in liquid and water systems. Every one of these should be sealed, eliminated, or designed so cleaning solution reaches it. The same logic applies to water systems, where dead legs are a known source of biofilm.
Does the Design Separate Zones and Control Traffic?
Facility-level sanitary design is about flow: people, materials, waste, and air. Raw material staging should not sit next to finished goods. Wet processes should be separated or contained from dry ones. Air should move from cleaner areas to less clean areas. Floors should be sealed and sloped to drains, with coved wall-to-floor junctions that can actually be mopped.
How Does Facility Design Differ From Equipment Design?
They are connected but they fail in different ways. A comparison helps.
| Element | Facility-level concern | Equipment-level concern |
|---|---|---|
| Water and drainage | Floor slope, drain placement, preventing backflow | Self-draining vessels, no dead legs, sloped surfaces |
| Airflow | Pressure cascades, filtration, zoning | Enclosures, dust collection, sealed transfer points |
| Pest exclusion | Sealed penetrations, door seals, no gaps | Sealed frames, no hollow members that shelter pests |
| Verification | Environmental monitoring, zone mapping | Swab and rinse sampling, visual inspection |
A well-designed room cannot rescue badly designed equipment, and excellent equipment placed in a poorly zoned room still gets contaminated from the outside.
How Do You Evaluate Equipment Before You Buy It?
This is where the most leverage sits. Once a machine is on your floor, qualified, and tied into production schedules, your options shrink. Before purchase I recommend a short, documented hygienic design review.
- Write the requirement into the user requirements specification. State cleanability, material, finish, and disassembly expectations explicitly. If you do not write them down, vendors will quote their standard model.
- Ask for material certificates and finish data. Request alloy certification, weld documentation, and surface roughness values for product-contact parts. As a common reference point, ASME BPE specifies a mechanically polished product-contact finish of Ra 0.5 µm (20 µin) or better for many bioprocessing applications, and 3-A criteria commonly reference Ra 0.8 µm (32 µin) for food equipment. Set the target in your URS based on the product and the standard you follow.
- Walk the vendor's reference installation or a demo unit. Bring a flashlight and a cleaning technician. The technician will find things the engineer will not.
- Try the cleaning. During factory acceptance testing, disassemble and reassemble the equipment, and ask how long it takes and whether it needs special tools. A cleaning step that takes three hours instead of thirty minutes becomes a downtime problem, and then a shortcut problem.
- Plan the cleaning validation early. 21 CFR 211.67 and its food and supplement equivalents expect written cleaning procedures. Your worst-case product, hardest-to-clean location, and sampling points should be identified from the design review, not guessed at later.
- Document the review. A one-page record of who reviewed what, what was found, and what the vendor agreed to change is worth having when an inspector asks how you selected the equipment.
What Do Inspectors Look For?
In my experience, these patterns come up repeatedly in inspections and audits. Equipment with damaged or flaking surfaces. Product residue in places the cleaning procedure does not cover. Duct tape or temporary repairs on product-contact parts. Wooden pallets or tools in processing zones. Standing water. Gaps at doors and wall penetrations. Cleaning records that look identical day after day for equipment that clearly cannot be cleaned in the stated time.
Under 21 CFR 211.67(b), written cleaning procedures must describe the equipment and the cleaning methods in enough detail to be followed. If the procedure and the equipment do not match, the procedure fails. That mismatch is a design problem showing up as a documentation problem.
Drug manufacturers should also read the facility provisions together with the equipment rules: 211.42 (design and construction features), 211.44 (lighting), 211.46 (ventilation, air filtration, air heating and cooling), 211.48 (plumbing), 211.56 (sanitation), and 211.58 (maintenance). For sterile products, FDA's 2004 guidance on sterile drug products produced by aseptic processing and EU GMP Annex 1 (with its contamination control strategy) set further expectations for surfaces, cleanability, and airflow.
What Are the Most Common Sanitary Design Mistakes?
Treating it as a purchasing detail. Sanitary design gets decided by whoever negotiates price. Quality should have a seat at that table from the start.
Modifying equipment without a review. A bracket gets welded on, a guard gets replaced with a cheaper one, a new sensor goes in with exposed threads. Each change is small. Together they erase the original design. Your change control process should ask a hygienic design question every time.
Relying on chemicals to make up for geometry. More aggressive cleaners and longer contact times can mask a design flaw for a while, but they also wear gaskets and surfaces, and they do not reach a spot the liquid cannot get into.
Ignoring maintenance as a contamination route. Lubricants, worn parts, and metal shavings from repairs all enter the product zone. Food-grade lubricants, controlled maintenance procedures, and post-maintenance cleaning checks belong in the design conversation.
Skipping the people side. Operators who were never told why a gasket must be seated a certain way will seat it however is fastest. This is why personnel training is part of sanitary design in practice, not a separate topic.
How Does Sanitary Design Connect to the Rest of Your Quality System?
It touches almost every part. Design review feeds equipment qualification. Cleaning validation depends on identifying worst-case locations. Environmental monitoring programs rely on zone maps that reflect how the building was designed. Preventive maintenance schedules should cover gaskets, seals, and weld integrity. Change control protects the design after installation. And deviations tied to contamination should loop back to a design question: did the equipment allow this to happen?
Where Should You Start?
The most useful first step is also the least glamorous: walk your own plant with fresh eyes and a flashlight, with a sanitation operator beside you. Pick your three hardest-to-clean pieces of equipment and ask whether you would buy them again today. The answer tells you where your real risk is, and it usually points to a short list of fixes that cost far less than a recall.
Good sanitary design is quiet. Nothing happens, because the residue never had a place to hide.
If you want an outside set of eyes on your equipment or facility, book a GMP review with us and we will walk through it with you.
Related Reading
- Salmonella prevention in dietary supplement manufacturing
- Sanitation program
- MoCRA GMP requirements
- GMP water system validation and monitoring
- Personnel training
- FDA inspection prep
- GMP first 90 days
Last updated: 2026-10-16
Frequently Asked Questions
What is sanitary design in GMP?
Sanitary design is the practice of building facilities and selecting or fabricating equipment so they can be cleaned and sanitized reliably and do not become a source of contamination. It covers surface finish, geometry, materials, drainage, airflow, and access for cleaning and inspection.
Which FDA regulations address equipment design for cleanability?
For drugs, 21 CFR 211.63 requires equipment of appropriate design to facilitate cleaning, 211.65(a) addresses surface reactivity, and 211.67 requires written cleaning procedures. For dietary supplements, 21 CFR 111.27 covers physical plant and equipment design. For human food, 21 CFR 117.40 requires equipment to be adequately cleanable and to protect against allergen cross-contact.
What are the most common sanitary design flaws?
Common flaws include hollow rollers or frame members, exposed threads, rough or pitted welds, sharp internal corners, dead legs in piping, equipment that cannot be disassembled without special tools, and horizontal ledges where product collects.
When should sanitary design be reviewed?
Before purchase, during factory acceptance testing, at installation and qualification, and every time a change control touches product-contact or adjacent parts. Reviewing at the specification stage is the cheapest point to correct problems.
Does sanitary design apply to cosmetics and OTC products?
Yes. OTC drugs fall under 21 CFR Part 211, so the equipment design provisions apply directly. Cosmetics do not yet have a finalized FDA GMP rule under MoCRA, but the same cleanability principles are a practical benchmark for inspection readiness.
Jared Clark
GMP Compliance Consultant, Certify Consulting
Jared Clark is a GMP compliance consultant and founder of Certify Consulting, specializing in FDA GMP requirements for pharmaceuticals, dietary supplements, cosmetics, and food manufacturing.