Short answer
OSHA 29 CFR 1926.51 requires 1 toilet facility for up to 20 workers, 1 toilet seat and 1 urinal per 40 workers from 20 to 199, and 1 per 50 workers at 200 or more. It is based on the peak crew on site, and separate provisions cover potable drinking water and hand washing where work involves contaminants.
Key numbers at a glance
| Item | Figure | Notes |
|---|---|---|
| Up to 20 workers | 1 toilet facility | The baseline requirement |
| 20 to 199 workers | 1 per 40 workers | 1 toilet seat and 1 urinal |
| 200 or more workers | 1 per 50 workers | 1 toilet seat and 1 urinal |
| Basis of the count | Peak crew on site | Not the project total |
| Potable water | Required | Separate provision in the same rule |
| Hand washing | Required where contaminants are present | Sanitiser alone is not equivalent |
| Practical ratio used | 1 unit per 10 workers | Industry norm, above the minimum |
What does the rule actually say?
29 CFR 1926.51 is the construction sanitation standard, and subsection (c) is the part that sets toilet provision. The structure is simple: one facility for up to 20 workers; from 20 to 199 workers, one toilet seat and one urinal per 40 workers; at 200 or more, one toilet seat and one urinal per 50 workers.
The ratio relaxing at 200 workers looks counterintuitive, but it reflects that very large sites have usage spread across a longer working day and more staggered breaks.
What counts as the worker number?
The number of workers on site at one time. That is your peak crew, not the headcount across the project and not an average.
This matters on sites where the crew size changes sharply between phases. A project running 60 workers during framing and 12 during fit out needs provision sized for 60 while framing runs, and can be scaled back afterwards. Reviewing provision at each phase change is both compliant and cheaper than carrying peak capacity throughout.
What else does the same rule cover?
Two things people often miss.
Potable drinking water has its own provision in the standard, including requirements about containers and dispensing. It is not satisfied by assuming workers will bring their own.
Hand washing is required where the work involves substances that could be harmful if ingested or absorbed through the skin. In those conditions a sanitiser dispenser is not equivalent provision, and a hand wash station with soap and running water is the straightforward way to comply.
Does the standard require separate facilities by sex?
The rule permits a single toilet facility where it can be locked from the inside and contains at least one water closet. Single occupancy portable units meet that description, which is why a bank of identical units satisfies the standard rather than requiring designated provision.
Why do contractors order above the minimum?
Because compliance and usability are different thresholds. One unit for 20 workers is lawful and will also be unpleasant by midweek on standard weekly servicing.
The industry norm is one unit per 10 workers, which matches the practical capacity of a 60 to 70 gallon tank across a five day week. At that ratio the unit is still usable on Friday, which is the outcome that actually matters.
What about state requirements?
OSHA state plan states may adopt stricter standards than the federal rule, and several have specific provisions on sanitation, servicing or facility type. If you operate in a state plan state, check the state standard rather than relying on the federal text alone.
Related guides and tools
Rental options
Questions
What is the OSHA standard for portable toilets?
29 CFR 1926.51 covers sanitation in construction. Subsection (c) sets the toilet facility ratios by the number of workers on site.
Is the OSHA figure a minimum or a recommendation?
A minimum, and it is enforceable. Most contractors order above it, because the minimum is compliant rather than comfortable.
How is the worker count determined?
By the number of workers on site at one time, meaning your peak crew. The total number of people who will work on the project over its life is not the basis.
Does OSHA require hand washing facilities?
Where the work involves contaminants that could be harmful if ingested or absorbed, yes. Hand sanitiser alone is not equivalent provision in those conditions.
Does OSHA require separate facilities by sex?
The rule allows a single facility where it can be locked from the inside and contains at least one toilet, which is how single occupancy portable units satisfy it.
Are there state rules on top of the federal standard?
Yes. OSHA state plan states can set stricter requirements, and some do. Check your state plan if you operate in one.
Who wrote this page
Written and fact checked by the Dumpster Porta Potty USA editorial team. We check container sizes, servicing intervals and price ranges against published provider rate sheets and federal guidance, then update the page when those change.
Last updated . Read our editorial policy.
Sources