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Setting Up a Reverse Osmosis System

Setting Up a Reverse Osmosis System

The Challenge

Being a pressure washing company, we clean a lot of RVs and fleet vehicles with pressure washers. We have arrangements with RV detailers around Utah, where we detail the exterior and interiors of the RVs that the dealership has either sold or is close to selling.  The dealer wants to please their customers with a dazzlingly clean RV when they come for their final walk through, so they rely on us to get the job done. One way to ensure this is by setting up a reverse osmosis system.

One of the biggest challenges we have with cleaning these RV’s is that the water that comes out of the tap is full of minerals and other deposits that tend to leave spots on the surface of the vehicle’s exterior if it is left to air dry. In order to fix this on our end, we have been using a squeegee to dry off the exterior of the vehicle once it has been washed. It takes our crews almost as long to dry it off as it takes them to do the initial cleaning. When it’s hot out, the water tends to dry faster than our cleaners can keep up with. These hot days also happen to be our busy season, so having to spend extra time wiping off water spots can put us at risk of missing cleaning deadlines.

Can a RO system solve our problem?

Some window washing services and car washes will use a filtration system on their water to prevent spotting.  After speaking with a few knowledgeable people we learned that setting up a reverse osmosis system would be the best way to ensure there was no spotting on the RV’s we regularly clean. However, these filters aren’t cheap, but we decided that if we could cut the time we spend on the exterior wash in half then the filter would quickly pay for itself.  Long story short, we decided that for our company, a RO system didn’t make sense. Below we have provided details on why we ultimately decided not to use it.

Setting Up a Reverse Osmosis System to Your Pressure Washer:

The way that RO works is water is forced through a semi-permeable membrane that has holes that are too small for contaminants and minerals to fit through. This membrane is expensive and needs to be replaced periodically, otherwise it will foul (clog up) and either stop working all together or you will have a much smaller flow.  So a pre-filter is necessary to extend the life of the RO filter. Also, water that isn’t able to make it through the filtration system is discharged, so you will run a lot of waste water down the drain and may need to come up with a plumbing solution for that if you are going to try it. 

The first thing you need to consider about using RO filters with a pressure washer is that you need to either have one that can filter at a high enough flow rate to keep up with your pressure washer or you need to pre-filter the water and store it.  We usually use pressure washers that do about 5 GPM (gallons per minute), so you need to have at least a little more than what your pressure washer is putting out coming in for it to function properly. If you don’t have enough water flowing into your machine then it’s going to stutter and have trouble spraying, which will ultimately result in it wearing down and breaking your pump (about $1,000 to replace a pump on the machines we use). There are RO filters that can filter water faster than 5 GPM, but they get quite pricey.  In our situation we like to store water in a tank, because at some of the dealerships we run into problems with water flow being too low due to high usage (technicians etc. filling up tanks on RVs and other problems). We opted to get a cheaper filter that has a flow rate of about 3 GPM (it was around $1,400) and use it to fill our holding tank. There were also a bunch of other considerations that added to the cost of the experiment. We operate in a location where we deal with freezing weather during the winter and we still do the detailing work outside.  Our holding tank is sitting outside and we keep tank heaters in it, so it doesn’t freeze. We also have a cart mounted pressure washer that we roll into the bay at night to avoid freezing. We didn’t want to leave the RO filter outside as it would be prone to freezing, so we built a wheeled cart to mount it on and wrapped in a thermostatically controlled heating wire so that while it was sitting outside it wouldn’t freeze either.

 Now that we were all set up it was time to try it out.

Why a RO was not a good solution for us…

The crew at the dealership started using the new system.  First they had to drain all the old hard water out of the tank and fill it with filtered water and then run the clean water throughout the system to flush out any scale that had built up inside.  Next they began washing. The RO worked as promised, meaning there were no spots. However, the trouble that they ran into was that when you wash a big RV or trailer with a pressure washer there are areas that you don’t get clean because you can’t see or reach them.  Most of the time you are spraying from the ground and are concerned primarily with cleaning what you can see from the ground, and as most people don’t climb up on the roof to admire their RV this is usually fine because the point of the detail is to make the RV look good.  So if you can’t see or reach it then it doesn’t matter if it’s dirty. The problem is that when you let the RV air dry, water will run and drip down the surface as its drying and find its way into the vents, cracks, window seals, and all these other places that didn’t get 100% clean when you pressure washed.  As it runs and drips it will pick up small dirt and mineral deposits that were in those nooks and crannies and leave those deposits on the side of the freshly cleaned RV (meaning you will end up needing to wipe the RVs down any way).

In conclusion, we think that setting up a reverse osmosis system will work well for other applications like detailing smaller vehicles but we don’t recommend it for RVs because you are going to have to wipe everything down any way.

Let us know if you had a different experience or other ideas that you would like to add.

Setting Up a Reverse Osmosis System

Visit the rest of our site to view more pressure washing tips and tutorials.

If you currently live in Utah and are needing pressure washing services, contact our sister company, AJET Services (801-330-0398 or

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