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What Is a Tunnel Washer?

Alex Newth
Alex Newth

A tunnel washer, also known as a continuous batch washer, is a large industrial washing machine used to clean towels and clothes for large institutions or businesses, such as hospitals and hotels. This works by placing the linens into a long tunnel with an Archimedes screw, which separates the linens into pockets, or batches. As the towels go from the beginning to the end, water and cleaning chemicals are sent backward, from the end to the beginning. After being washed, any clean water is recycled by pressing down on the linens, creating a cake that is mostly free of any liquid.

The tunnel washer is an expensive washer, usually costing around $1 million U.S. Dollars (USD) or more in 2011, and is meant only for industrial use. These washers typically wash around 3,000 pounds (about 1,361 kilograms) of linens at once, making them perfect for institutions or businesses that constantly need clean clothes and towels. The entire system is computerized, and operators are able to change the amount of cleaning chemicals with a push-button interface.

Woman holding a disc
Woman holding a disc

When linens are placed in the tunnel washer, they go through a tunnel that has an Archimedes screw. The screw is very large and makes up most of the tunnel washer. Large pockets in the screw section off the laundry to make cleaning more effective; each pocket usually holds around 200 pounds (about 91 kilograms) of linens. This screw also is the primary locomotion of the linens, which go from the beginning to the end of the machine.

As the linens move in one direction, the Archimedes screw is moving water and cleaning chemicals in the other direction, against the linens. This causes the linens at the beginning to encounter dirty water and used chemicals, while the end encounters clean water and chemicals, making it efficient for cleaning the entire tunnel. The screw itself is porous, making it a good carrier for both the linens and the cleaning substances.

When the linens are deposited at the end of the tunnel, they are saturated with clean water that can be reused. To get the most water out of the linens and reduce operating costs, the linens are placed in a hydraulic press. The press uses force to squeeze the fresh water out, and the water is placed back into the tunnel washer. After being squeezed, the linens are in a cake shape, which is then deposited into a dryer to finish the laundering process.

Discussion Comments


A million dollars for a tunnel washer might be doable for a hospital with lots of funding, but some hotels are just too small to afford one. I know that many smaller motels just have a room with several regular sized washers instead.

I stayed at a hotel in Ohio that was fairly large, and I overheard some workers complaining about having to constantly do laundry. The hotel didn't have enough money to afford a tunnel washer, so workers had to monitor a dozen regular sized washers and dryers often.

I heard one worker telling another that some guests had been complaining because of the wait for clean towels. The worker had passed this onto the manager, but he said that they couldn't do anything about it. A million dollars simply was not in the budget.


@lighth0se33 – I have a friend who is a serious germaphobe, and she actually called several hotels and asked them how often they washed their bedspreads before choosing one to stay at. What she found out may disturb you.

Most of the hotels told her that, on average, they wash the bedspreads once a week. A few just said they wash them when they look dirty.

So, the chances are high that when you stay at a hotel, you are sleeping on a used comforter. This is enough to make me bring my own blanket.

The tunnel washer would just be too rough on comforters if they were washed after every guest checked out. However, they wash the sheets after every use, so you should be safe sleeping on them and bringing your own quilt or blanket from home.


I wonder how often most hotels have to do a load of laundry with an awesome washer like this. Three-thousand pounds amounts to a lot of towels and sheets. It makes me think they might have to only do one load a day.

I always see the housekeepers rolling their dirty towels around in carts from room to room. I would think that they would have to wash them every day in order to have plenty of replacements on hand.

I am curious about one thing, and I'm almost scared to ask. Does anyone know how often hotels wash their comforters? It seems like washing them after every use would cause them to wear out, especially in a strong tunnel washer.


I have seen hotel workers tossing linens down a chute before, but I never knew exactly where it led to. That is cool that they are throwing it into an actual washer.

I picture the towels and sheets spiraling down something resembling a slide at a playground as they get shot with soapy water. It sounds like a really effective, intense cleaning. That makes me feel better about using hotel towels.

That fast-moving water must be pretty hot, too. It has to sterilize the things that guests share every day.

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