Reverse Osomosis Drinking Water System – DIY Project

Considering RO? – you have things to learn and COMPROMISES to make

As an RV’r do you worry about the quality of the water you drink? Are you concerned about the amount of plastic (water bottles) that you are placing into the waste stream?

We were and decided to do something about it. I did a lot of homework before I purchased a system. There are a lot of variables to consider prior to purchasing and installing on of these systems. Not educating yourself could set you up for having a system that doesn’t fit your needs. So, before you embark on this project get the information you require.

what levels of total dissolved solids (TDS) are safe to drink?

To understand why TDS is important you need to identify the contaminants, minerals and chemicals in the water you drink. The EPA monitors water conditions and has set acceptable levels for human consumption. There is a lot of stuff in our water with some of it good and some of it bad. However, some of the bad stuff is really bad for you. Your water may contain some or all of the following:

  • Lead
  • Chromium6
  • Arsenic
  • Motor Oil
  • Pesticides
  • Pharmaceuticals
  • Detergents
  • Fluorides
  • Chlorine and Chloramine
  • Nitrates
  • Sulfates

Ok, so it’s there – How do we measure this stuff?

You can begin by purchasing a TDS Meter so that you can measure the parts per million of contaminates in the water you drink. This will not tell you what chemicals you are drinking but rather it will give you a sense of whether the water is suitable for drinking or not.

So what are acceptable levels of TDS (Total dissolved solids)?

The EPA set standards for drinking water levels and most if not all TDS Meters test for those levels. Is this an exact snapshot of your water? No. But TDS tier levels are set in parts per million PPM and the meter will give you an indication of what you are dealing with:

  • 0 50 ppm -RO Water, Distillation Water. Deionized Water – Acceptable for drinking
  • 50 – 100 ppm – Carbon Filtered Water, Mt. Streams (away from cities) – Preferable for drinking
  • 100 -200 ppm – Hard Water – Acceptable for drinking
  • 200-300 ppm – Marginally acceptable for drinking (this is also the average for tap water in the United States).
  • 400 -500 ppm -The EPA’s high limit for tap water and marginally acceptable for drinking
  • 500 -600 ppm – EPA Max level deemed safe for drinking but marginally

as an rv’r you are on the road – knowing what we are drinking is essential – How to choose a system that works for you.

As I said above, you need to do your homework. You need to determine your average gallons per day usage for your family first. This will determine the size of the RO system you purchase. For us, we are two with a dog. We average about 3 gallons of drinking water per day and it is used for drinking water, cooking, coffee and water for our small dog.

Our total RO ouput is sized on my estimated water usage. Our system comes with a 4 gallon holding tank. This system and tank supplies us with 8-10 seventeen ounce bottles of water, water for drinking, cooking and coffee on a daily basis. Our system does have one caveat, it takes about 1.5 – 2 hours to re-generate 4 gallons of water if I empty it. And this is based on available incoming water pressure and the temperature of the water (more on this later).

If you are a family of four the RO System we purchased isn’t going to work for you.

Another determination is whether or not you’ll be using the system for just drinking water or for water for the whole house (RV). If whole house RO is your requirement your installation will be more complicated. What do I mean by “complicated?” Well, you need to consider the following:

The links I have provided in the text above are just for informational purposes. You will have to find the appropriately sized system and parts that will work for your needs and application.

How does an RO system remove impurities?

Reverse Osmosis water purification process is a simple and straightforward water filtration process. It is accomplished by water pressure pushing tap water through a semipermeable membrane to remove impurities from water. This is a process in which dissolved inorganic solids (such as salts) are removed from a solution (such as water). 


Generally speaking the more stages of filtering that your RO system has, the better the RO water you get to drink. The system above is a four stage system.

There Are Generally Four Stages In The Reverse Osmosis Process:


This pre-filter stage is designed to strain out sediment, silt, and dirt and is especially important as the sediment filter protects dirt from getting to the delicate RO membranes that can be damaged by sediment.


The carbon filter is designed to remove chlorine and other contaminants that affect the performance and life of the RO membrane as well as improve the taste and odor of your water.


The semipermeable RO membrane in your RO system is designed to allow water through, but filter out almost all additional contaminants.


In a four-stage RO System, a final post filter (carbon filter) will “polish” off the water to remove any remaining taste and odor in the water. This final filter ensures you’ll have outstanding drinking water.

RO water filtration is not without it’s flaws

When producing RO water what happens to the waste that the system filters out? Well, this is the downside to RO systems. Most cost effective systems waste more water than they produce. In fact most RO systems produce one gallon of RO water and 1.5 – 2 gallons of waste water called “permeate” water. Having pure water is good for you but what do you do with the permeate water? Well, it’s waste therefore it goes down the drain of course. If you are in boondocking it will need go into your grey tank. Why is this bad? You’re boondocking. The second most precious commodity in your arsenal (besides battery storage) is storage of fresh and waste water. So, to visualize this consider that for four gallons of RO drinking water you have created eight gallons of waste water. You have a thirty two gallon grey water tank…umm you do the math. How many days can you stay based on your grey tank and don’t forget doing dishes, water for showers and use at the bathroom sink.

If you are not boondocking it can go down the parks sewer system. But, if you are in a State, C.O.E., BLM or National park you will be required to be self contained and you will not be able to discharge this water onto the ground (some BLM locations will let you discharge grey water but not all). If you are out west where water is scarce and precious it would likely (I really don’t know, but I am guessing) be a ticketing offense for discharging water onto the ground.

During my research online and in forums some folks proposed installing a second gray tank and pump and pumping the permeate water into that tank and in turn pumping that water on demand to flush their toilets. In this example you require two more water pumps and various other parts but you are still limited to the size of the tank for storage and you would need to find a way to shut off the permeate discharge and the RO system before the tank gets full.

Other things that must be considered is your incoming water pressure. In our travels we have seen from 25-65 psi from the park. The RO membrane becomes more efficient at higher pressures of 65-80 PSI. When sizing your system you need to know your consumption and you need to know your desired RO output. The following chart will help you understand the efficiency of an RO system vs water pressure and water temperature. It will also help you determine expected production wherever you are based on incoming water pressure and the temperature of the water.

An advantage to Whole House RO is that water scaling and hard water deposits are history

Whole house keeps your pipes (Pex tubing) from scaling, your fixtures from becoming prematurely disabled due to scaling and deposits. But there is that whole “where do I store the pure water” thing. What is the alternative?

Whole house vs Drinking water only

Ok, we tossed around the idea of whole house and that of drinking water only. What if you want advantages that they both provide?

We opted for drinking water only. This allowed us to get good water consitently with equipment that has a very small footprint. A footprint that fits under our RV sink without loss of storage.

I still wanted whole house water conditioning so that hard water deposits don’t ruin fixtures or show on glass surfaces and the coaches paint when I wash it. Knowing this I also knew that I don’t want the hassle of using my fresh water tank to act as storage for my RO water. Instead I will be purchasing a portable softer water conditioner. This will soften the water to the for all other faucets and for multiple purposes.

As for boondocking with our present system we will turn off the RO during the time we are in the boonies and store water in bottles for use prior to arriving at the boondock site.

Whats an RO system look like when installed and how hard was it to do?

In our case making room for the RO equipment was a pain in the neck. No, I mean literally a pain in the neck for three days after the installation.

I chose to install our system under our RV’s kitchen sink. Getting the system in place without loosing essential storage that the cabinet provided was a priority. Under our sink Newmar installed a shelf that ran from side to side and it was really a pain to put anything on it and as such there was only one or two things on it before the project.

Most of the work was done laying on my back. This is really tough and exhausting in an RV because of the way RV cabinets are built.

To accommodate the RO water storage tank I decided to cut out part of that shelf . This proved to be a really hard task and I ended up using a drywall saw to cut the shelf piece out by hand because of limited accessibility with a power saw or jig saw. Once the shelf had been altered I put the tank in place and boxed it into the corner with a 1″X 4″ and placed a vertical support on the corner of the remaining shelf .

The next toughest thing was getting the RO water supply faucet into place. Again, this is an extremely difficult place to reach. I required the help of my wife Martha to hold the faucet in place while I tightened the required nuts from below.

After the shelf alteration and faucet installation the rest of the installation was easy and straight forward. The manufacturer (Apec in the case of my system) provides quality pex fittings and color coded 1/4″ tubing and a really great set of illustrated instructions.

The installation instructions included verbage like “place the red tubing between attachment point X and attachment point G. Prior to installing the tubing I used a marker to label the indicated points directly at the attachment points on the equipment itself. I did this because it became necessary to snake the tubing around and under things and it was done best with the RO filter and tank in their intended mounting place.

Another slow part of the installation was the attachment of the RO permeate discharge line onto the sink drain pipe. The instructions indicated that the attachment of this disharge line saddle clamp needed to be at the top of the drain line pipe and not on the side. My drill with the bit installed would not clear the bottom of the sink so I couldn’t get the right angle to drill the required 1/4″ hole. I opted instead to remove the drain line from the sink and drill it while it was out, install the saddle clamp and reinstall the drain pieces.

All in all removal of the piece of shelving delayed my project by more than an two hours. Once that part was done the rest of the project went quick.

When I installed our system I decided to anchor the accumulation tank permanently to keep it from getting shuffled around during transit. The RO system itself is attached via bungee cords and is against the cabinet wall. I purposely didn’t cut any of the RO tubing so that I could release the bungee cords and pull the RO and the excess tubing out onto the kitchen floor to change filters.

What do I need to buy in addition to the RO System?

The system I purchased included everything except a water supply shut off valve. I went to a local hardware store and bought a 1/4″ to 1/4″ Pex shut off valve. The shut off valve was $10 and that was my cost above the RO unit but I also purchased a cheap tray ($1.29 for use under potted plants) to catch any potential leaks at the tank tubing attachment and I’m still looking for an appropriately sized plastic bin to set the RO filter canisters in for the same reason.

I hope this article will help you understand RO Systems a little better. Remember to do your homework. It will pay off.

One comment

  1. I’ll be handing fans of WanderingToes $100 when they ditch free WP for a turnkey money-making blog… First, I want to address your RO System!

    It’s been a week or so Charlie, is everything still holding? If so, you should be in the clear! I wouldn’t know what to do with an RO System, let alone put it together- that’s why I stick to fishing and copy. RVers looking to do exactly what you did, will benefit triumphantly from recording your handy work…

    In order to make it big online, you can’t restrict yourself… Never fall into the “everything is free” trap. you’ll only damage your chance of getting people to act.

    Take your links. You can pretty your links up right now to make them more appealing to readers… People are so trained on the amazon aff link, something happens to their brain… turning them off- they become paralyzed- making it impossible for them to act.

    When you pretty them you’re actually guiding your fans to see more of what you want them to see… If they trust you, they’ll be willing.

    And as your fans they’re getting this for $100 less than I charge others (shhh don’t repeat that), they’ll get access to my web hosting and 1 free domain name, for life… You know that’s not all… It never is…

    To get this upgraded no-risk profit blog click my gravatar, go to my site… find and fill out the contact form… and when I’m not swamped (within 12 hours) I reply… I’m only going to do this for 2 people. Any more, my current clients will freak and want their money back.

    Best To You and Your Wife Charlie,


    P,S, This letter was written and sent to you, not sure if you saw it?


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