How Many Portable Toilets Do You Actually Need?
Under-provision is one of the most common mistakes event organisers and site managers make when booking portable toilet hire. Getting the numbers wrong creates long queues at events, welfare compliance failures on construction sites, and — frankly — a bad experience for everyone involved. This guide covers the key recommendations and how to apply them.
The short answer: use the HSE guidance for construction sites and the Showman's Guild guidelines for events, then add a buffer for high-usage situations. The rest of this article explains what that means in practice.
Portable Toilets for Construction Sites
The Health and Safety Executive sets out welfare requirements for construction sites in the CDM Regulations 2015 and supporting guidance. The headline figure is one toilet per seven workers on a site without access to mains sanitation (HSE, L153 Managing Health and Safety in Construction, 2023).
This applies to all workers on site, regardless of employment status — direct employees, subcontractors and self-employed tradespeople all count. If your peak workforce is 14 people, you need at least two portable toilet units.
Account for Shift Patterns
The one-in-seven rule applies to the number of workers present at any one time, not the total project workforce. If you're running two shifts of 10 workers each, you need toilets for 10, not 20. But if both shifts overlap during changeover, you need to size for the peak overlap number.
Accessible Provision on Construction Sites
If any worker on site has a mobility impairment or disability that means they cannot use a standard portable toilet, you must provide a suitable accessible unit. This is a welfare requirement regardless of workforce size.
Portable Toilets for Events
For outdoor events, the Showman's Guild of Great Britain publishes guidance that is widely used by event organisers and local authority licensing teams. Their current recommendation is one toilet per 50 attendees for events up to 4 hours, and one per 35 attendees for events over 6 hours (Showman's Guild Guidance, 2023).
Gender Split Matters
Women typically take longer to use toilet facilities than men. The Showman's Guild recommends that at least 60% of total provision should be female units where the gender split is unknown. Where you expect a predominantly female audience — a hen party event, for example — increase this to 70 to 75%.
Alcohol Service Increases Usage
Events where alcohol is served see significantly higher toilet usage than dry events. Add 20 to 30% to your baseline calculation for licensed events. This is not a vague rule — it reflects real differences in usage rates recorded at comparable events.
A Simple Worked Example
A summer music festival in a Liverpool park. Expected attendance 400. Duration 8 hours. Alcohol licensed.
Base calculation: 400 ÷ 35 (over 6 hours) = 12 units. Alcohol uplift 25%: 12 × 1.25 = 15 units. Female provision at 60%: 9 female, 6 male. Minimum 2 accessible units (at 1 per 100 attending with disabilities).
Total recommendation: 17 units including 2 accessible, with female-designated signage on 9 standard units.
Frequently Asked Questions
What happens if I don't provide enough toilets at an event?
At a licensed event, your local authority licensing officer may require additional provision as a condition of the licence. At unlicensed events, inadequate provision can lead to complaints and reputational damage. On construction sites, insufficient welfare facilities can result in HSE enforcement action including prohibition notices.
Can I add extra units on the day if needed?
We can sometimes accommodate last-minute additions, but it depends on fleet availability at the time. It's far better to build in a small buffer when booking — an extra unit costs less than the disruption of trying to arrange an emergency delivery on event day.