How many toilets does your event need? A practical sizing rule

The question we hear most before any event: how many units do we need? The answer in foreign references doesn’t work here, because it spreads attendance evenly across the event’s hours. In Saudi Arabia the load isn’t spread evenly — it bunches up five times a day around prayer times. This guide sets out the rule we actually work to, and why it is different.

The basic rule

Start from the expected number of visitors per day, not from the number of event hours:

• A 40 ft unit serves roughly 500 visitors a day.
• A 20 ft unit serves roughly 250 visitors a day.

An event with five thousand visitors a day needs ten 40 ft units or the equivalent. The figure assumes the waste tank is pumped twice a day — without that, the whole calculation fails however many units you add, because a full unit stops working.

The peak comes at prayer times, not midday

This is the practical difference between event portable toilets in Saudi Arabia and elsewhere. Attendance doesn’t flow evenly: it gathers before each prayer and then disperses. The queue that looks impossible at Dhuhr leaves the site almost empty half an hour later.

That is why we don’t recommend cutting the number of units for short events. A four-hour event may include one or two prayers, and those are its whole peak. Size on visitor numbers and ignore the duration.

Ablution: the highest water use

The biggest mistake in planning festival portable toilets is calculating water on toilet use alone. The highest consumption comes from ablution (wudu) before each prayer, not from ordinary use.

So we usually separate public bathrooms for ordinary use from wudu bathrooms with dedicated basins, seats and wider drains. Separating the ablution units takes pressure off the main units, shortens queues at the same time, and reduces water running across the floors.

In the major seasons the effect multiplies. Planning portable toilets for Hajj starts from ablution first, then everything else.

What usually gets left out of the calculation

• Accessible facilities. Accessible public bathrooms are not an optional extra but a requirement in most permits: a wider door, grab rails, a ramp instead of steps, and turning space for a wheelchair.
• Moving events. If the event moves between locations or runs along a long route, a mobile toilet truck solves the problem without installing and dismantling at every point.
• Supply and drainage. A fresh-water tank that gets refilled and a waste tank that gets pumped. If either stops, the unit stops.
• Distribution, not just numbers. Ten units in one corner are worse than five spread around the edges of the site.

Four numbers to send us

1. Visitors per day — on the busiest day, not the average.
2. Number of event days — this sets the pumping and refilling schedule.
3. Site area and gathering points — so units are distributed, not stacked together.
4. What is available on site — power? A water source? A road that can take the pump truck?

How we work at Advance Cabin

We calculate the number from these four figures, supply, install and distribute the units across the site, and run them throughout the event: wastewater removal, water refilling, and technical follow-up through a single contact number. When the event ends, we dismantle and remove.

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