OSHA Porta Potty Requirements for Construction Sites (1926.51)

OSHA's construction sanitation rule, 29 CFR 1926.51(c), requires toilets on construction jobsites based on headcount: 1 facility for 20 or fewer employees, 1 toilet seat and 1 urinal per 40 workers at 20 or more, and 1 toilet seat and 1 urinal per 50 workers at 200 or more. OSHA has also said in interpretation letters that a toilet that is unsanitary, or too far away, doesn't count as provided. States can be stricter, so check your state and local rules.

This page summarizes the federal regulation and OSHA guidance as published on osha.gov, checked October 21, 2026. It's not legal advice.

Regulation, interpretation or standard: what's what

• Regulation: 29 CFR 1926.51 is an OSHA regulation. It's enforceable law for covered construction employers.
• Interpretation: OSHA's letters of interpretation explain how OSHA reads the regulation. They're official guidance, not new rules.
• Consensus standard: ANSI Z4.3 is an industry consensus standard for nonsewered sanitation. It isn't law unless a jurisdiction adopts it, though OSHA has pointed to it as a guide.
• State rules: states with their own OSHA-approved plans, like California, can set different or stricter requirements.

Table D-1: minimum toilets on construction jobsites

29 CFR 1926.51(c)(1) says: Toilets shall be provided for employees according to the following table. Table D-1, reproduced as written:

• Number of employees 20 or less: minimum number of facilities 1.
• Number of employees 20 or more: 1 toilet seat and 1 urinal per 40 workers.
• Number of employees 200 or more: 1 toilet seat and 1 urinal per 50 workers.

Two things to notice. First, the table's own wording overlaps at exactly 20 employees. Second, the regulation doesn't spell out how to handle a partial group, such as 45 workers on the 1 per 40 line. Rounding up is the conservative approach, but confirm with your safety professional for a specific site.

Temporary field conditions: 1926.51(c)(2)

The regulation says: Under temporary field conditions, provisions shall be made to assure not less than one toilet facility is available. In plain terms, even a short-term or remote job needs at least one toilet.

Sites without a sewer: 1926.51(c)(3)

Job sites not provided with a sanitary sewer must have one of the following, unless prohibited by local codes:

• Privies (where their use will not contaminate ground or surface water)
• Chemical toilets
• Recirculating toilets
• Combustion toilets

Chemical toilets are what most people call porta potties. Note the local-code carve-out: a city or county can prohibit an option, which is another reason to check local rules.

The mobile crew exception: 1926.51(c)(4)

The toilet requirements in paragraph (c) don't apply to mobile crews having transportation readily available to nearby toilet facilities. This covers crews that move from spot to spot during the day and have a vehicle to get to a restroom. It doesn't cover a crew parked at one site for weeks.

What counts as provided: OSHA's interpretations

Unsanitary toilets aren't provided (May 17, 2006)

In a May 17, 2006 interpretation letter, OSHA was asked whether toilets in an unsanitary condition count toward the Table D-1 minimum. OSHA's answer was no: toilets that are unsanitary are unusable and therefore not available, so a toilet is not provided under 1926.51(c)(1) if it's in an unsanitary condition.

The same letter said one way to meet the sanitary-condition obligation is to use the servicing schedule in ANSI Z4.3-1995 as a guide. OSHA gave two examples: a toilet for 10 employees serviced once per week would likely be provided in a sanitary condition, and one toilet for 20 employees serviced twice per week would likely be too. Note the word likely: this is guidance, not a fixed servicing rule.

Too far away isn't provided (February 23, 2005)

In a February 23, 2005 interpretation about a high-rise where toilets were only on the ground floor, OSHA said toilets that take too long to get to aren't considered provided. It pointed to an earlier letter on the mobile crew exception that said toilets would generally be considered nearby if it takes less than 10 minutes to get to them, and said the same starting point applies to 1926.51(c)(1). On tall buildings or big sites, that can mean placing units closer to where people work, not just at the gate.

State example: Cal/OSHA section 1526

California's construction rule, Title 8 section 1526, is stricter than the federal table in several ways. This is state regulation and applies to California jobsites:

• A minimum of one separate toilet facility for each 20 employees or fraction thereof of each sex.
• Facilities may include both toilets and urinals, but toilets can't be less than half of the minimum required number.
• Exception: where there are fewer than five employees, one single-user all-gender toilet facility is sufficient. A second exception covers how single-user all-gender facilities count toward the total.
• Under temporary field conditions, at least one toilet must be available.
• Where there's no sanitary sewer or adequate water supply, nonwater carriage facilities such as chemical toilets may be used, unless local regulations prohibit them.
• Facilities must be kept clean, maintained in good working order, provide privacy, and have an adequate supply of toilet paper.
• The rule doesn't apply to mobile crews with readily available transportation to nearby toilets.

Other states with their own plans may have their own rules too. Check your state and local rules before you finalize a site's count.

A jobsite checklist for GCs and operators

1. Count peak headcount on site. If several employers' crews share the same units, agree on who is counting whom.
2. Apply Table D-1, or your state's rule if it's stricter, and round partial groups conservatively.
3. Check whether the site has a sanitary sewer; if not, confirm local code allows chemical toilets.
4. Place units so workers can reach them quickly, including on upper floors of tall buildings.
5. Agree on a servicing frequency that keeps units sanitary as headcount changes; ANSI Z4.3 is a common reference.
6. Re-check the count when the crew size changes during the job.
7. Keep service records so you can show what was on site and when it was serviced.

For portable restroom operators

Contractors often ask their porta potty provider how many units they need. Sending them this page, or the osha.gov text itself, helps the conversation. Keep in mind that the employer is responsible for compliance, and the right count and service frequency depend on the actual crew.

If you use Magic Lav, each jobsite record carries the units needed there and its service schedule, so you can show a customer exactly what's on site and how often it's serviced.

Sources

29 CFR 1926.51 Sanitation, osha.gov (regulation)

29 CFR 1926.51, eCFR (regulation)

OSHA interpretation, May 17, 2006: unsanitary toilets are not provided

OSHA interpretation, February 23, 2005: timely access to toilets

Cal/OSHA, Title 8 section 1526: Toilets at Construction Jobsites (state regulation)

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