How to Clean Portable Restrooms: Route Service, Wash Bays and Wash Water Rules
Portable restrooms are pumped and wiped down on the route, but a full hot water wash belongs in a wash bay that drains to the sanitary sewer or a holding tank. If you wash units in the field, you need a way to capture every gallon, because that wash water can't go to a street or storm drain. San Diego County, for example, requires portable toilet cleaning to be done in a wash bay with the wastewater sent to the sanitary sewer.
Portable sanitation is a big, route-driven business. The Portable Sanitation Association International (PSAI) counts about 1,200 US companies that focus mainly on portable sanitation, and up to 9,100 that offer it alongside other services. Every one of them has the same problem: units come back from job sites and events dirty, and the water used to clean them is regulated.
What's the difference between route service and a full wash?
Route service keeps a unit usable between visits. The driver pumps the tank, wipes down surfaces, restocks and recharges. It's fast and it happens wherever the unit sits.
A full wash is a deeper clean of the shell, floor, walls and urinal, usually with a pressure washer. It removes the buildup that a wipe-down leaves behind, and it's what gets a unit ready for its next rental, especially for events where appearance matters.
The two jobs have different water rules. A wipe-down uses little water. A pressure wash produces runoff that has to be captured.
Why can't portable toilet wash water go down the storm drain?
Storm drains carry water straight to creeks and bays with no treatment. San Diego County's guidance on portable toilets says only rainwater belongs in streets and storm drains, and that cleaning wastewater can carry pathogens, bacteria, parasites and viruses.
The county's rules are a good model of what to expect elsewhere:
Cleaning toilets and related equipment must be done in a wash bay that contains the water.
The wastewater must go to the sanitary sewer.
Units should never be placed on or near a storm drain.
Every truck that hauls toilets should carry spill equipment.
The county's portable toilet cleaning fact sheet adds that service-yard wash areas need perimeter control, a slope to a grated drain, and drainage to the sanitary sewer or a holding tank, with sewer agency approval before you discharge.
Texas cities treat mobile washing the same way. Fort Worth, for instance, requires mobile cleaners to collect wash water before it leaves a property and forbids discharges into manholes. Call your city stormwater office and sewer district before you set up a wash area.
Where should you wash: the yard, the route or a mobile rig?
Approach | Where the water goes | Best for | What you need |
Route wipe-down | Little or no runoff | Between-service cleaning on site | Pump truck, wipe-down supplies |
Yard wash bay | Contained bay draining to sanitary sewer or holding tank | Full washes between rentals | Hot water pressure washer, contained pad, sewer approval |
Mobile wash with recovery | Vacuumed up and held in a tank | Large job sites and events where units can't come back to the yard | Hot water washer, recovery vacuum, holding tank |
Most operators use the yard bay for full washes. A mobile rig with recovery earns its place when you service big construction sites or multi-day events and can't haul every unit back.
Why use hot water to wash portable restrooms?
Heat breaks down organic film, grease and grime faster than cold water. In practice that means fewer passes, less detergent and less wash water to capture. Our guide to hot water vs. cold water pressure washers explains when heat pays for itself.
Flow matters as much as pressure. Rinsing a unit's walls and floor is a flow job, so size the washer by GPM, not just PSI. See PSI vs. GPM for how to size it.
How do you set up a compliant wash bay?
Contain the pad. Curb or berm the wash area and slope it to one collection point.
Get sewer approval. Ask your sewer district whether you can discharge, and whether a grit trap or permit is required.
Keep units away from drains. Stage dirty and clean units away from storm drain inlets.
Use hot water. A hot water skid or trailer washer at the bay cuts wash time per unit.
Plan for field washes. If you'll wash on site, add a recovery vacuum and holding tank.
Carry spill gear. Keep absorbents and drain covers on every service truck.
What equipment fits a portable sanitation operation?
For a yard bay, a hot water skid you can mount on your own truck or a stand gives you heat without buying a trailer; see the Slider skid on Hot And Mighty Direct. If you already own a washer and need to capture water in the field, read adding wash water recovery to your existing pressure washer.
Frequently asked questions
Can I pressure wash portable toilets on a customer's job site?
Only if you can capture the wash water. Block nearby storm drains and vacuum the water into a holding tank for approved disposal. Many operators bring units back to a yard wash bay instead.
Can portable toilet wash water go into the sanitary sewer?
Usually, with approval. San Diego County requires it to go to the sanitary sewer, and its fact sheet says to get all required sewer agency authorizations first.
How hot should the water be?
Hot enough to cut organic film and grease; your washer's adjustable thermostat lets you set it. Watch discharge limits too: Fort Worth, for example, accepts mobile wash water in the sanitary sewer only at or below 150°F, so ask your sewer district about its limit.
Do I need a separate washer for the yard and the route?
Not always. A skid can serve a yard bay, and a trailer with recovery can do both. Tell us how many units you wash and where, and we'll suggest a setup.
Talk to us about your wash setup
Hot And Mighty has 50+ years of experience building hot water wash, recovery and recycling systems, delivered nationwide. Tap "Text us" on this page or call 800-897-7515, Monday to Friday 9 to 5 EST, and tell us how many units you service and where you wash them.
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