Kohler Mobile Unit Provides On-site Showers for Volunteers and Workers At The World Trade Center.
To bring a few minutes of respite to the workers and volunteers at the World Trade Center, Kohler Co. created a mobile showering unit that was located at Ground Zero. A first for the company, the unit incorporated nine shower stalls and four sinks in a massive semi-trailer. It offered hot showers with an infinite supply of hot water.
Led by Kohler Co. industrial designer, a team of more than 150 electricians, engineers, carpenters, welders and other Kohler associates designed the showering unit in two days and built in four days.
Nine showers stalls self contained with its' own shower and hot water supply for use by rescue workers at ground zero 24 hours a 7 days a week. Powered by Kohler generator, water supplied by fire hydrant. All self contained in a Mobile Shower Truck.
Unlimited Hot Water Supplied by SETS Tankless Water Heaters Model 180. 
The Little Giant is what the Kohler Co. called it and here is what they had to say...
I am pleased to inform you that after nearly three months of continuous use, between 100-200 showers per day/per unit, your units are still working fine. The entire unit was just moved from NYC yesterday and is now at a Kohler facility.
Thanks again for all your help.
- Kohler Design Engineer.