How to size a shower trailer to your crew
The first question on any rental is simple. How many people, and how fast? Get that right and the rest falls into place. A shower point that fits a ten-person crew will drown under a hundred, and a big rig parked for a handful of workers just burns money. So start with your peak, not your average.
Count the shift change, not the headcount. What matters is how many people hit the showers in the same window. Twenty workers who trickle in over three hours need far less than twenty who all clock out at once. Walk your schedule and find the worst crunch of the day. So that peak is the number to size around.
A rough rule helps. One stall can turn over several people in an hour if the hot water holds and nobody is waiting on the stall to warm back up. So a single suite covers a small crew with a loose schedule, and a larger multi-stall unit covers a big crew coming off one shift together. When the math sits between two sizes, go up. A short line is cheap. A long one costs you time every single day.
Do not over-buy either. A giant unit parked for a small crew wastes money and site space, and it is more to move and service. The goal is a snug fit: enough stalls to clear your peak line, and not a door more. Match the unit to the crowd, not your worst-case fear.
Hot water is the real limit, not the stall count. A trailer with plenty of stalls but a weak heater will run cold by the fifth person, and then the line stops. Ask about the heater and the tank, not just the number of doors. Heat is the ceiling. High-output, continuous hot water is what lets a unit actually hit its rated turnover.
Think about who else is on site. A public spot, or any crew with a worker who needs step-free access, should plan an ADA suite from the start. It has ramp entry, a roll-in threshold, a fold-down seat, and grab bars. Adding it up front costs nothing extra in hassle. Bolting it on after an inspection does.
Plan for growth on a long job. Crews swell as a project ramps, so the size that fit month one can choke by month four. Talk through the arc of the job before you sign. A good provider will right-size as you go, swapping a single suite for a bigger unit or adding a combo when the count climbs.
Write down three numbers before you call. Peak crew size, the length of the shift-change window, and the length of the rental. With those, a provider can spec the right unit in one conversation instead of guessing. Bring them, and you skip the back-and-forth.
Sources: Cal/OSHA (Division of Occupational Safety and Health) · CAL FIRE Incidents
What to ask before you rent a portable shower trailer
Not all shower rentals are the same, and the gap shows up after the trailer lands, not before. A few plain questions up front save you the headache. Here is what to run through before you sign anything.
Start with the water. Ask whether the unit runs off its own tanks or needs a hookup. On a remote site with no water line, a self-contained trailer is the only thing that works. Ask how big the fresh tank is and how long it lasts between fills, so you know how often a truck has to come out.
Ask about the dirty water next. In California the used shower water cannot just drain onto the ground. Confirm the unit captures its greywater onboard and that the provider hauls it to a permitted site as part of the deal. If that answer is fuzzy, keep looking. A dumped tank becomes your problem, not theirs.
Pin down the service. Who cleans the stalls, who restocks supplies, and how often? On a long job you want daily service in writing, not a promise to swing by. Ask whether the trailers are sanitized between rentals. And ask what happens if something breaks at 2 a.m.
Ask about hot water like you mean it. How many people can shower back to back before it cools off? A unit that looks big but heats slow will let you down at the worst moment. The honest answer names the turnover, not just the stall count.
Cover access. Ask whether an ADA suite is available and what it includes. The right answer is ramp entry, a roll-in threshold, a fold-down seat, and grab bars. If a provider has never been asked that, it tells you what kind of jobs they usually run.
Sort out delivery and site fit. What does the truck need to get in and drop the unit? How much level ground does it want, and how far can it sit from the water and power you do have? Answer these before the truck rolls, not while it idles at your gate.
Last, ask what the price actually covers. Does it include delivery, setup, service, greywater hauling, and pickup, or are those line items waiting to surprise you? A flat, all-in rental is easier to plan around. Get the full list in writing and you will not get a bill you did not see coming.
Sources: California State Water Resources Control Board · California Division of the State Architect (accessibility)
Running hot showers off-grid at a remote camp
Plenty of California jobs sit where there is no water line and no power drop for miles. A canyon staging area. A desert range. Open farmland at the end of a dirt road. The showers still have to work. So how does a trailer make hot water with nothing to plug into?
It carries everything with it. A self-contained unit holds fresh water in an onboard tank, heats it with its own onboard heater, and catches the used water in a second tank. Nothing runs to a building. Drop it on level ground, level it, and it works.
The heater is the heart of it. A good unit heats water fast enough to keep up with a line, not just one shower at a time. Off-grid hot water comes down to one thing: the heat has to keep pace with the draw, or the fifth person in line gets a cold surprise. Ask how the heater is powered and how long it holds temperature under a steady pull.
Fuel and power come along for the ride. Off-grid units run their heat and pumps off onboard fuel or a generator, so they do not wait on a utility. Someone has to keep that topped off, which is part of the service on a managed rental. On a long stay, that visit lines up with the daily cleaning and the water refill.
Water in, water out, both on a schedule. The fresh tank empties as crews shower, and the greywater tank fills at the same rate. On a busy site both get handled on a service run, so the unit never runs dry and never backs up. Plan those runs around your peak, not your slow hours.
Weather plays a part. In a cold snap an off-grid unit works harder to hold temperature, so a strong heater matters even more in winter. Ask how the unit holds up when the nights drop. In California that question is not just for the mountains anymore.
The moment a hookup shows up, a smart unit uses it. If a water line or a power drop finally reaches the site, the trailer ties in and stops leaning on its tanks. Best of both: it works with nothing, and it works better with something. You do not have to choose up front.
Site prep is short but real. The unit wants firm, level ground and a clear path for the truck. Get those two things sorted before delivery and an off-grid shower point is running within the hour of the trailer landing.
Sources: CAL FIRE Incidents · California Governor's Office of Emergency Services
Site prep and daily service for a portable shower trailer
A shower trailer is only as good as the spot you put it and the service that keeps it running. The rental gets a lot easier when you sort both before the truck shows up. None of it is hard. It just has to be done.
Start with the ground. A trailer wants firm, level footing so it sits stable and drains right. Soft dirt after a rain, or a hard slope, will fight you. Pick a spot that stays solid, and mark it so the driver drops the unit in the right place the first time.
Leave room for the truck. The delivery rig needs a clear path in, room to swing, and space to pull out later. Low branches, tight gates, and parked equipment are the usual snags. Walk the route once before delivery day and clear it.
Put the unit where people already are. A shower point tucked far from the work just means a longer walk and less use. Keep it close to the crew break area but out of the traffic lane for heavy equipment. Close, but not in the way.
Think about the two tanks. The fresh tank needs a way for a truck to reach it for refills, and the greywater tank needs the same for pump-outs. If a service truck cannot get to the unit, the service cannot happen. Leave that lane open the whole rental, not just on drop-off day.
Daily service is what keeps it usable. On a real rental a crew cleans the stalls, restocks supplies, refills the fresh water, and hauls the greywater on a set schedule. Ask for that in writing on any job that runs more than a day or two. Set-and-forget is how a good unit turns into a bad one by the end of the week.
Keep a simple record. On a long job, a quick note of each service visit tells you the unit got cleaned, stocked, and pumped on schedule. If an inspector ever asks, you have the answer ready. It also flags a missed visit before your crew does.
Point out power and water if you have them. If a hookup is anywhere close, tell the provider before delivery so the unit can tie in instead of leaning on its tanks. And keep a name and number on your side who the service crew can reach. A five-minute heads-up beats a half-day of a cold shower point.
Sources: Cal/OSHA (Division of Occupational Safety and Health) · California State Water Resources Control Board
