Short answer: OSHA requires one toilet facility for job sites with 20 or fewer workers. Above 20 workers, the standard requires one toilet seat and one urinal per 40 workers. At 200 or more workers, the ratio changes to one toilet seat and one urinal per 50 workers. These minimums come from 29 CFR 1926.51(c), Table D-1.
That’s the rule. The rest of this page covers what the rule actually means in practice — including the parts that get misquoted most often, and the requirements that sit alongside it.
The OSHA ratio, exactly as written
The governing standard is 29 CFR 1926.51(c)(1), part of Subpart D. Table D-1 sets the minimum:
| Number of employees | Minimum number of facilities |
|---|---|
| 20 or fewer | 1 |
| 20 or more | 1 toilet seat and 1 urinal per 40 workers |
| 200 or more | 1 toilet seat and 1 urinal per 50 workers |
One correction worth making, because it circulates widely: the standard is not “one unit per 20 workers.” That figure appears in a lot of contractor guidance and it is wrong. Twenty is the threshold below which a single facility satisfies the standard — not a per-unit ratio.
A standard portable restroom contains one toilet seat. Many models also include a urinal, which means a single unit can satisfy both elements of the ratio. Where units don’t include a urinal, you need to account for that separately.
Worked examples
Crew of 12 — One portable restroom meets the minimum.
Crew of 35 — One toilet seat and one urinal per 40 workers. One unit with an integrated urinal meets the minimum. Most contractors place two, because a single unit on a 35-person site creates queues and takes the site out of compliance the moment that unit is out of service.
Crew of 80 — Two toilet seats and two urinals. Two units with integrated urinals meets it.
Crew of 240 — Now at the 200-plus threshold: one toilet seat and one urinal per 50 workers. Five toilet seats and five urinals.
Practical note: these are legal minimums, not recommendations. On a large site, the number of units that keeps a crew productive is usually higher than the number that keeps you compliant. Waiting time is the constraint that costs money, and OSHA has itself connected adequate unit counts to timely access — the point of the ratio is that workers shouldn’t be standing in line.
A unit in poor condition doesn’t count
This is the part that catches contractors out.
In a May 2006 interpretation letter, OSHA confirmed that toilets in an unsanitary condition do not count toward the minimum required by Table D-1. The reasoning is straightforward: the standard requires that toilets be provided, OSHA reads “provided” as “made available,” and a unit that is unsanitary is unusable — and therefore not available.
A site with two units where one is unusable is a site with one unit, as far as the standard is concerned.
The practical consequence: on a 40-person site running the bare minimum, a single unserviced unit puts you out of compliance without anything visibly changing. This is the strongest argument for building a servicing buffer into the count rather than ordering to the exact minimum.
How often do units need servicing?
The regulation itself doesn’t state a servicing frequency. But OSHA has pointed to one, and this is the part most guidance on the subject leaves out.
In the same 2006 letter, OSHA stated that one way an employer can meet its sanitary-condition obligation is to use the servicing schedule in ANSI Z4.3-1995, Section 3 — the industry consensus standard for non-sewered waste-disposal systems — as a guide. That schedule calls for a toilet used by up to 10 people to be serviced at least once per week.
OSHA then worked through two examples:
- One toilet provided for 20 employees, serviced twice per week — would likely be considered sanitary
- One toilet provided for 10 employees, serviced once per week — would likely be considered sanitary
In the ANSI standard, “servicing” means emptying the waste and cleaning the toilet facility.
OSHA also noted, in a footnote worth knowing about, that 1926.51(c) does not require toilet facilities to be in immaculate condition to be considered sanitary. The test is usability, not perfection.
Service frequency should increase beyond that baseline when:
- More than ten workers per unit
- Multiple shifts running on the same units
- Sustained high temperatures — a significant factor on Central Texas sites from May through September
- Sites with restricted access, where a missed service can’t easily be caught up
A weekly service visit typically includes pumping the waste tank, cleaning and sanitizing interior surfaces, and restocking toilet paper and hand sanitizer.
Handwashing: the requirement is narrower than most guidance suggests
A lot of contractor-facing content states that handwashing stations with soap and running water are required on all construction sites. That is not what the standard says, and the distinction matters if you’re specifying a site.
29 CFR 1926.51(f)(1) requires adequate washing facilities for employees engaged in applying paints, coatings, herbicides or insecticides — or in other operations where contaminants may be harmful to employees. OSHA has interpreted that “other operations” clause broadly, covering a wide range of activities beyond the four listed, and the test is whether workers are handling materials that are actually harmful. Where they are, the employer must provide facilities adequate to remove those contaminants, including soap and potable water.
Separately, 1926.51(f)(3) requires lavatories with running water — but OSHA has clarified that because of how that provision was derived, it applies only to permanent places of employment. Construction sites typically are not permanent places of employment.
What this means in practice: if your crews are working with harmful contaminants, washing facilities are required and hand sanitizer alone won’t satisfy the standard. If they’re not, the requirement doesn’t automatically apply — though many general contractors specify handwash stations contractually regardless, and it’s a reasonable baseline on any site with food breaks taken on-site.
If you’re unsure whether a material on your site qualifies, the Safety Data Sheet is the reference point.
Drinking water is part of the same standard
29 CFR 1926.51(a) requires an adequate supply of potable water at every place of employment. Portable containers must be capable of being tightly closed and equipped with a tap, containers must be clearly marked as to their contents, and common drinking cups are prohibited. Where single-service cups are provided, there must be a sanitary container for the unused cups and a receptacle for the used ones.
On Central Texas job sites this stops being a paperwork item somewhere around June. Water consumption on a site in triple-digit heat is dramatically higher than the same site in March, and freshwater tank capacity needs to be sized for the season rather than the average.
ADA-accessible units
OSHA’s construction sanitation standard does not itself specify ADA-accessible portable restrooms. The obligation usually arises from somewhere else:
- Reasonable accommodation under the ADA where a worker on site needs an accessible facility
- Contract specification — many general contractors and public agencies require at least one accessible unit regardless of crew composition
- Public-facing sites, where members of the public may access the facilities
An ADA-compliant portable restroom is a wider unit with ground-level entry, a larger interior turning radius, and handrails. On sites where it’s specified, it typically counts toward the overall Table D-1 minimum as well as satisfying the accessibility requirement.
Multi-story and high-rise sites
Placing all units at ground level on a high-rise build can fail the standard even when the count is correct.
OSHA addressed this scenario directly in a 2005 interpretation: the requirement is that toilets are provided, and the agency reads “provided” as “made available.” Facilities that take too long to reach are not, in OSHA’s interpretation, available. Where workers are several floors up with no functioning lift or hoist, ground-floor-only placement may not satisfy 1926.51(c)(1).
The practical answer on multi-story work is crane-accessible units placed on the working floors and repositioned as the build progresses. These are reinforced, compact units fitted with lifting points.
Mobile crews
1926.51(c)(4) exempts mobile crews from the on-site toilet requirement where transportation is readily available to nearby facilities. OSHA has interpreted “readily available” as requiring prompt access — the test is whether workers can actually reach a facility quickly, not whether one theoretically exists somewhere in the area.
The exemption is narrower than it looks. It applies to genuinely mobile crews, not to a fixed site that happens to be near a gas station.
Texas specifics
Texas has no state-run OSHA program covering private-sector construction, so federal OSHA standards apply directly and are enforced by federal OSHA area offices. There is no separate state ratio to reconcile against 1926.51.
What does change in Central Texas is the practical load on the same requirement. Extended summer heat drives up water consumption, accelerates odor and sanitation problems between services, and makes the difference between weekly and twice-weekly servicing far more consequential than it would be in a milder climate. On sites in Georgetown, Liberty Hill, Hutto and the Bell County corridor, we routinely move commercial sites to increased servicing between May and September for exactly this reason.
Quick reference
| Requirement | Standard | What it says |
|---|---|---|
| Toilet count | 1926.51(c)(1) | 20 or fewer: 1 facility. 20+: 1 seat and 1 urinal per 40. 200+: 1 per 50 |
| Sanitary condition | 1926.51(c)(1), 2006 interpretation | Unusable units don’t count toward the minimum |
| Servicing frequency | ANSI Z4.3-1995 §3, cited by OSHA | Weekly for up to 10 workers per unit; twice weekly for 20 per unit |
| Washing facilities | 1926.51(f)(1) | Required where workers handle harmful contaminants |
| Drinking water | 1926.51(a) | Potable, tightly closed, tapped, marked; no common cups |
| Temporary field conditions | 1926.51(c)(2) | At least one facility must be available |
| Mobile crews | 1926.51(c)(4) | Exempt where prompt access to nearby facilities exists |
Frequently asked questions
How many porta potties does OSHA require per worker on a construction site?
For 20 workers or fewer, one facility. For more than 20 workers, one toilet seat and one urinal per 40 workers. For 200 or more workers, one toilet seat and one urinal per 50 workers. These figures come from Table D-1 of 29 CFR 1926.51(c)(1).
Is it one porta potty per 20 workers?
No. That’s a common misreading. Twenty is the threshold below which one facility is sufficient — not a per-unit ratio. Above 20 workers the ratio is one toilet seat and one urinal per 40 workers.
Does a dirty porta potty count toward the OSHA minimum?
No. A 2006 OSHA interpretation letter confirmed that toilets in an unsanitary condition do not count toward the required minimum, because a unit that is unusable has not been “provided.” A site with two units where one is unusable is treated as having one.
How often does OSHA require portable toilets to be serviced?
The regulation doesn’t state a frequency, but OSHA’s 2006 interpretation letter points to the servicing schedule in ANSI Z4.3-1995, Section 3 as one way to meet the sanitary-condition requirement. That schedule calls for a unit used by up to 10 people to be serviced at least once per week. OSHA worked two examples: one toilet for 20 employees serviced twice per week, and one toilet for 10 employees serviced once per week, would each likely be considered sanitary. Weekly servicing is the standard baseline on long-term rentals.
Does a porta potty have to be spotless to meet OSHA’s requirement?
No. OSHA noted specifically that 1926.51(c) does not require toilet facilities to be in immaculate condition to be considered sanitary. The test is whether the unit is usable, not whether it is perfect.
Are handwashing stations required on construction sites?
Only where workers are engaged in applying paints, coatings, herbicides or insecticides, or in other operations involving contaminants that may be harmful. Where that applies, facilities must be adequate to remove those contaminants, including soap and potable water. The running-water lavatory requirement applies to permanent places of employment, which construction sites typically are not.
Does OSHA require ADA-accessible portable toilets on job sites?
Not under 1926.51 itself. The requirement usually comes from ADA reasonable accommodation where a worker needs an accessible unit, from contract specifications, or from the site being publicly accessible. Many general contractors specify at least one accessible unit as standard.
Do porta potties need to be on every floor of a high-rise build?
Not necessarily every floor, but ground-level-only placement can fail the standard. OSHA reads “provided” as “made available,” and facilities that take too long to reach are not available. Crane-accessible units placed on working floors are the usual solution.
Do mobile crews need portable toilets on site?
Not where transportation is readily available to nearby facilities, under 1926.51(c)(4). OSHA interprets this as requiring genuinely prompt access, and the exemption applies to mobile crews rather than fixed sites that happen to be near a public facility.
Getting the count right on your site
Cap City Rentals supplies construction restroom rentals across Central Texas, from single-unit residential builds to multi-hundred-worker commercial sites. If you tell us crew size, project duration and site access, we’ll tell you what the standard requires and what we’d actually recommend — those aren’t always the same number.
Call or text 512-643-7286, or request a quote.