You are a pretty good Do-It-Yourselfer and you have been wanting to get a reverse osmosis system for some time now but you’re not sure if you can install it yourself. Putting it together and running the tubing should be a snap, but what about the drain?
A drain is needed for a reverse osmosis system to discharge the water that is rejected by the reverse osmosis membrane. This wastewater carries away the impurities that are removed by the reverse osmosis system.
Every reverse osmosis system will need a drain to get rid of the unwanted wastewater that is produced by the process of reverse osmosis, that’s just the way it works. But installing your new reverse osmosis is quite simple, and installing the drain line is easier than you think.
Why does a reverse osmosis system need a drain?
The process of reverse osmosis removes dissolved solids like sodium from the water by forcing the water through a semi-permeable membrane that allows the water to pass through but rejects the unwanted impurities.
To remove the impurities from the water, the system uses water to rinse the impurities down a drain. In most cases, a reverse osmosis system will simply be able to tap into an existing drain from your kitchen sink.
If a reverse osmosis system is not connected to a drain line, the water containing the impurities would get forced through the membrane, causing the quality of the water to be poor and potentially damaging the reverse osmosis membrane.
Where does the drain have to be connected to?
In most cases, a reverse osmosis system can be installed right underneath your kitchen sink. In this situation, the drain line from the reverse osmosis system can easily be attached to a drain saddle that connects directly to the drain of your sink.
To do this you will only have to drill a small hole into the drainpipe, attach the drain saddle over the hole, and then insert the drain line into the drain saddle. Make sure that the drain saddle is centered over the drain hole, or the reverse osmosis system will not work correctly.
In circumstances where a reverse osmosis system is not installed underneath a kitchen sink, you can run the drain line to any drain pipe but I recommend installing a one-way check valve in the line to prevent other drain water from entering the reverse osmosis system drain line.
If you are installing your reverse osmosis system in or near a laundry room, you could simply run the drain line into the drainpipe that the washing machine feeds into and secure the tubing with some strong tape.
Does the drain have to be right next to the reverse osmosis system?
Not at all! Because the drain line of a reverse osmosis system is not under pressure, a drain line can be run to a drain many feet away from the reverse osmosis system. I have run a drain line over 20 feet away from the reverse osmosis with no problems whatsoever.
The only time that I would NOT recommend running the drain line too far from the reverse osmosis system is if you are running it straight up.
Although running the drain line upwards for several feet should not pose any problems, having a drain line that goes up 20 feet may cause some back pressure on the membrane causing the system to not produce the best quality water that it could.
Does the drain line need to be a certain size?
The provided drain line that comes with a reverse osmosis system should work fine for most applications. The most common drain line sizes for residential reverse osmosis systems are 1/4 inch to 3/8 inch tubing which is designed to work with that particular system.
If you are running the drain line a longer distance than the provided tubing allows, you should replace the tubing with a longer piece of the same size tubing. Using a larger or smaller sized tubing may cause improper back pressure to the reverse osmosis membrane.
If this happens, the membrane may not filter out impurities as it should. The water draining from a reverse osmosis system must be able to flow freely in order for the system to work most efficiently.
Are there water filters that do not need a drain?
A typical water filter does not need a drain because that is not the way a typical filter works. A filter captures the unwanted particles to be filtered out, and then the filter has to be either cleaned or replaced.
If you are only looking to filter out sediment or some chemicals from your water, you could install an inline water sediment filter or use a water filtering pitcher.
But that is not how a reverse osmosis system works. A key factor as to why residential reverse osmosis filter systems are so popular is because the semipermeable membrane that removes the dissolved solids from the water does not capture the impurities.
Instead, a reverse osmosis membrane rejects the impurities and rinses them down a drain. This prolongs the life of the membrane and allows it to filter water at peak efficiency for a longer period of time before requiring replacement.
A reverse osmosis system absolutely does need to have a drain to dispose of the impurities that it is removing. Without a drain, a reverse osmosis system will make poor quality water because the impurities have nowhere to go.
is the reverse osmosis sytem drain always suposed to be draing or only when your are getting water? because my GE R.O. system is always draining at about 1 gallon every 20 minutes, that seem like a lot of water wasted to me.
estrada1459@msn.com
Hello Tony, and thank you for the question.
A reverse osmosis system should start to drain when it starts to make filtered water. Most standard type reverse osmosis systems will run about 4 gallons of water down the drain for every 1 gallon of filtered water produced.
This means that if you use 1 gallon of water from your reverse osmosis system, the system will run about 4 gallons of water to the drain to replace the 1 gallon of water that you used, which could take up to about 1 hour.
See my article “How long does it take to refill a reverse osmosis tank”
Check your reverse osmosis system when you know that it has not been used for several hours. It should be silent with no water going to the drain until you draw water from the faucet. Draw at least 8 ounces of water to trigger the system to make filtered water and then you should hear the system draining until the 8 ounces of water have been re-plenished.
I hope this was helpful.
Paul
Hi Paul:
Can the drain line from my RO unit (an Aqua-sure 64000 grain system) go to a 2″ drain line that is actually a few feet higher then the line origin? I set mine up to go into a drain line that runs through the ceiling of my basement. I did also install a backflow preventer.
Hello Peter and thank you for the question.
That should be no problem at all!
The Aqua-sure uses a Fleck brand valve that should provide more than enough water flow to backwash correctly providing the incoming water pressure is good. If you have poor water pressure, I would run the drain line straight up and then have it go horizontally to the drain to prevent back pressure bit as long as you have a backflow preventer installed, I don’t expect that you will have any problems.
I hope this was helpful.
Paul