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OSHA Porta Potty Requirements for Construction Sites

What OSHA 1926.51 requires: how many porta potties per worker, worked examples, the 10-minute rule, hand washing, separate facilities and stricter state rules.

SiteRento Team13 min read

Short Answer

OSHA's construction sanitation rule, 29 CFR 1926.51(c), sets the minimum number of toilets on a job site by headcount:

  • 20 or fewer workers: 1 toilet.
  • 20 or more workers: 1 toilet seat and 1 urinal per 40 workers.
  • 200 or more workers: 1 toilet seat and 1 urinal per 50 workers.

A toilet only counts if it is sanitary and workers can reach it promptly, which OSHA has read as generally less than 10 minutes away. State plans such as California's can require more.

This guide quotes the federal rule, works through the math, and covers the OSHA interpretation letters that explain it. It is written for general contractors and for the porta potty operators who supply them. It is not legal advice. Rules and interpretations change, so confirm current requirements with OSHA and, where one applies, your state plan. All sources are linked in the text and listed at the end, checked on September 29, 2026.

What 29 CFR 1926.51(c) Says

Section 1926.51 is OSHA's sanitation standard for construction. Paragraph (c), "Toilets at construction jobsites," has four parts. Paragraph (c)(1) says toilets "shall be provided for employees according to the following table." This is Table D-1 as published in the regulation:

Table D-1, 29 CFR 1926.51(c)(1)
Number of employeesMinimum number of facilities
20 or less1.
20 or more1 toilet seat and 1 urinal per 40 workers.
200 or more1 toilet seat and 1 urinal per 50 workers.

The other three parts:

  • (c)(2) Temporary field conditions. "Under temporary field conditions, provisions shall be made to assure not less than one toilet facility is available."
  • (c)(3) Sites without a sewer. Job sites "not provided with a sanitary sewer" must have one of four types of toilet "unless prohibited by local codes": privies (where they will not contaminate ground or surface water), chemical toilets, recirculating toilets, or combustion toilets. A standard porta potty is a chemical toilet.
  • (c)(4) Mobile crews. The toilet requirements "shall not apply to mobile crews having transportation readily available to nearby toilet facilities."

How to Read the Table

The table is short, and it leaves three questions open.

  • Exactly 20 workers. The first two rows overlap at 20. Either reading gives one toilet seat, and the second row adds a urinal.
  • Rounding. The table does not say how to round. It says "per 40 workers," not "per 40 workers or fraction thereof." Rounding any fraction up is the conservative reading, and it is the one we use below.
  • Seats and urinals. A toilet seat and a urinal do not have to be separate units. A fact sheet from NAWIC, written through its alliance with OSHA, notes that most portable toilets have both, but some have only one. Check the model before you count it as both.

One quirk: the ratio loosens at 200. With rounding up, 199 workers need 5 seats and 5 urinals (199 ÷ 40), while 200 workers need 4 of each (200 ÷ 50). Few customers will want fewer units as the crew grows, but the math allows it.

Worked Examples: How Many Porta Potties per Worker

The federal minimum comes straight from Table D-1. The last column shows the voluntary ANSI/PSAI Z4.3 figure of one unit per 10 workers, covered below, for comparison.

WorkersTable D-1 rowMathOSHA minimumANSI/PSAI Z4.3 (weekly service)
1520 or less—1 toilet2 units
4520 or more45 ÷ 40 = 1.125, rounded up to 22 toilet seats and 2 urinals5 units
12020 or more120 ÷ 40 = 33 toilet seats and 3 urinals12 units
250200 or more250 ÷ 50 = 55 toilet seats and 5 urinals25 units

With units that have both a seat and a urinal, the OSHA minimum for 45 workers is two units. The industry standard for the same crew is five. That gap is why the service schedule matters so much at the legal minimum.

"Provided" Means Clean and Close

Placing the right number of units is not enough. OSHA has said in interpretation letters that a toilet only counts if workers can actually use it.

It must be sanitary

In a May 17, 2006 letter, OSHA was asked whether unsanitary toilets count toward the minimum. Its answer was no: "a toilet is not 'provided' under §1926.51(c)(1) if it is in an unsanitary condition." The letter also says the standard does not require toilets to be immaculate.

OSHA does not set a cleaning frequency. The same letter points employers to the ANSI Z4.3 servicing schedule as one way to meet the obligation: a toilet used by up to 10 people serviced at least once a week. By that measure, it says, one toilet for 20 employees serviced twice a week would likely be sanitary. Our guide to how often porta potties should be serviced covers schedules in detail.

It must be reachable within about 10 minutes

In a February 23, 2005 letter, OSHA considered workers on the 10th floor of a high-rise with stairs as the only way down and toilets only on the ground floor. OSHA said "provide" means "make available," and that "toilets that take too long to get to are not 'available.'" It applied the test from its 2002 letter: in general, toilets are nearby if it takes less than 10 minutes to get to them. On a tall building, that can mean units on upper floors.

Mobile Crews and Temporary Field Conditions

The mobile crew exception in (c)(4) is narrow. In a June 7, 2002 letter, OSHA said mobile crews "must have prompt access to nearby toilet facilities," and that toilets would generally be nearby if it took less than 10 minutes to get to them.

An April 19, 1993 letter says who counts as a mobile crew. OSHA gave power transmission line crews as an example, with continual or frequent moves between job sites during the day. It said housing construction crews typically are not mobile crews. A crew that stays on one site all day needs toilets on that site.

Even under temporary field conditions, (c)(2) still requires at least one toilet facility to be available.

Separate Facilities, Privacy and Women on Site

The text of 1926.51(c) does not mention separate facilities for men and women. The general industry rule does. 29 CFR 1910.141(c)(1)(i) requires toilet rooms "separate for each sex," except where a room holds one person at a time, locks from the inside, and has at least one toilet. OSHA's restrooms and sanitation overview states that employers must provide toilet rooms separate for each sex, citing that general industry table. We did not find an OSHA interpretation letter that applies the separate-by-sex rule to construction.

In practice, a standard porta potty is a single-occupancy unit with a door lock, as Satellite Industries describes it. The NAWIC fact sheet recommends that toilets provide privacy, including locks, be separated by gender, be no more than 10 minutes from where people work, and be well lit, ventilated and in a secure area. Some states write sex separation into their rules, as California does below.

1910.141 is not the construction rule

Section 1910.141 applies to "permanent places of employment." Construction sites follow 1926.51. The general industry rule has its own, different table of water closets by headcount, so do not mix the two when you quote a job site.

Hand Washing: What 1926.51(f) Requires

Paragraph (f) covers washing facilities. Two parts matter on a job site.

  • (f)(1) requires "adequate washing facilities for employees engaged in the application of paints, coating, herbicides, or insecticides, or in other operations where contaminants may be harmful to the employees." They must be "in near proximity to the worksite."
  • (f)(3) says "lavatories shall be made available in all places of employment," with hot and cold or tepid running water, soap and towels. In a July 20, 2005 letter, OSHA said this lavatory requirement applies only to permanent places of employment, and that construction sites typically are not.

Where (f)(1) applies, the same letter says waterless hand cleaner and rags are not an adequate substitute for soap and water, so plan on a hand wash station with water and soap. Beyond the rule, the NAWIC fact sheet recommends soap and water or antibacterial cleanser, towels and trash cans.

State Plans Can Be Stricter

Some states run their own OSHA-approved programs. According to OSHA, there are 22 State Plans covering private sector workers, and each must be at least as effective as federal OSHA. A state's rule can match the federal one or go further.

California is one example. Title 8, §1526 requires "a minimum of one separate toilet facility" for each 20 employees "or fraction thereof of each sex." Urinals can count, but toilets must be at least half of the minimum. Sites with fewer than five employees can use one all-gender single-user toilet. Section 1526 also requires toilets to be kept clean, in good working order, private, and stocked with toilet paper.

The difference is real. A California crew of 40 men and 5 women needs 2 facilities for the men and 1 for the women: 3 in all. Federally, 45 workers need 2 toilet seats and 2 urinals. Check the state plan wherever you work.

ANSI Z4.3 Is a Separate, Voluntary Standard

ANSI/PSAI Z4.3 is the portable sanitation industry's consensus standard. It is not a regulation, but OSHA's 2006 letter uses its servicing schedule as a guide. PSAI's 2020 guidance describes the 2016 edition as one unit per 10 workers for a 40-hour week. ANSI's blog adds that one unit can serve 15 workers when units are serviced more than once a week, and that the count should be figured for men and women separately. If a customer's contract or safety plan names ANSI Z4.3, quote to it rather than to the OSHA minimum.

What About ADA Units?

The 2010 ADA Standards exempt portable toilets used only by construction personnel on a construction site (section 203.2). Public events are different: where single-user portable units are clustered, 5 percent of the units in each cluster must be accessible. The construction exemption covers only units used by construction personnel.

What This Means for Porta Potty Operators

The contractor is the employer, so compliance is the contractor's job. But the operator decides what gets quoted and how often it gets serviced. A few habits help:

  • Ask for peak headcount, not today's. Crews grow as a project ramps up.
  • Ask how many women are on site, and whether the job is in a state plan state.
  • Quote the OSHA minimum and the ANSI/PSAI count side by side, and let the customer choose.
  • On tall buildings, ask how long it takes to get down, and offer units on upper floors.
  • Recheck the count when the crew grows, and keep service records the customer can show.

SiteRento's porta potty rental software helps with the operator's side. You quote the units a crew needs. When the crew grows, you add units, and completing the delivery updates the job's unit count. Recurring service is scheduled from the install and follows the units on site. SiteRento does not check OSHA compliance or calculate these ratios; that stays with you and your customer. To compare tools, see our guide to the best porta potty software.

Frequently Asked Questions

How many porta potties does OSHA require per worker on a construction site?

Under 29 CFR 1926.51(c), a site with 20 or fewer workers needs 1 toilet. With 20 or more workers, it needs 1 toilet seat and 1 urinal per 40 workers. With 200 or more, it needs 1 toilet seat and 1 urinal per 50 workers. Rounding fractions up, 45 workers need 2 seats and 2 urinals, 120 need 3 of each, and 250 need 5 of each. Most portable toilets have both a seat and a urinal.

Does OSHA say how often porta potties must be cleaned?

No fixed frequency. But in a 2006 interpretation letter OSHA said a toilet in an unsanitary condition is not provided, so it does not count toward the minimum. The letter points to the ANSI Z4.3 servicing schedule as a guide: a toilet used by up to 10 people serviced at least once a week.

How far can a porta potty be from workers?

The construction rule does not set a distance, but OSHA interpretation letters say toilets must be promptly available, and that in general they are nearby if it takes less than 10 minutes to get to them. On a high-rise with stairs only, that can mean units on upper floors.

Does OSHA require separate porta potties for men and women on construction sites?

The construction rule, 1926.51, does not mention it. The general industry rule, 1910.141, requires toilet rooms separate for each sex unless each room is single-occupancy and locks from the inside, and OSHA's sanitation overview states that requirement. Some state plans, such as California's, require separate facilities for each sex on construction sites.

Does OSHA require hand washing stations on construction sites?

Where workers apply paints, coatings, herbicides or insecticides, or work with other harmful contaminants, 1926.51(f)(1) requires adequate washing facilities near the work, and OSHA has said waterless hand cleaner is not an adequate substitute for soap and water. OSHA has said the running-water lavatory rule in 1926.51(f)(3) applies only to permanent places of employment, which construction sites typically are not.

Does OSHA 1910.141 apply to construction sites?

No. Section 1910.141 is the general industry sanitation standard and applies to permanent places of employment. Construction sites follow 29 CFR 1926.51. States with their own OSHA-approved plans may have different or stricter construction rules.

The Bottom Line

OSHA 1926.51(c) requires one toilet for up to 20 workers, one seat and one urinal per 40 workers above that, and one of each per 50 workers at 200 or more. The units must be sanitary and within about 10 minutes of the work. State plans and the voluntary ANSI/PSAI standard often call for more.

Size to peak headcount, check the state rules, and keep the units serviced. A dirty toilet does not count.

This article is general information, not legal advice. Confirm current requirements with OSHA and any state plan that covers your site.

Keep unit counts and service in step with the crew

See how a delivery updates the job's count and how recurring service follows the units on site.

Sources

All sources opened on September 29, 2026.

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