RO water systems, how have you modded yours to your liking, mods, tips & tricks etc.


Although I am no expert, while investigating the differnt types available and reading hundreds of posts on the subject I picked up a few ideas,tips,tricks and mods along the way.
I think the main reason why people are put off an RO system is the amount of waste water that comes out of the discharge and washed away down the drain.
Many people live in counties, regions where water is metered just like electricity. Here in Spain almost every town and city have water meters that meter your usage and you pay accordingly, in the south it gets to a point where water is rationed in the summer and you are not allowed to wash your car at home, water your garden etc. I'm lucky living in the north in a very rural area I have my own well like many, but even so I always try to save water where posible.
Having a well I have a 1.5hp motor to pump water from the well to a large 2500 litre tank and because this tank is almost at the same level as the shower head I have another automatic booster pump 3/4hp that keeps pressure in the house circuit and turns on when the pressure drops. I also have a bypass that will give much lower pressure for likes of the WC that fills up slowly by gravity using no electricity.
My options were get a normal system that ran either by gravity fed or water booster pressure fed or a system with its own pump that has a small booster pump tailored to fit and uses the gravity fed line, these motors are between 100 - 400w @24v depending on your system and very small compared to a 3/4hp booster. This is the system I decided on as pure gravity fed only gave me 1.4 bar well short of the 3.5 bar recomended pressure. First a brief description of the systems
Next decision, how many stages, a stage is a filter and this depends on what your personal needs are, for only aquarium use and with no chlorine in your input water a simple 3 stage will do, paticle, membrane and carbon block polisher.
If you are on a city water system you need to take out the chlorine/chloramine or it will destroy the RO membrane in a very short time so you need to put a carbon block filter before the membrane, many just reroute the existing circuit and place the final carbon filter after the particle filter, it works but better membrane life can be had by adding another stage/filter so we now have particle, carbon granular, carbon block then to the membrane and to output.
Next is the 5 stage, probably the most common and all this does is add a carbon filter after the membrane to clean out any taste/plastic odours from the final water, personally I cannot tell the difference in the end product anywhere after the membrane.
Depending if you want to drink the water and or use it for cooking you need to put back necessary minerals like calcium & magnesium you just took out to make it taste somewhat decent so we need to add a remineralization stage
If you have reef tanks(or any other for that matter) you might like to add a DI filter, DI is deionisation, this removes phosfate, nitrate, silicate ions from the water and is a refilable resin that the water must pass through, maybe someone else can chime in on this as I have never used one(yet)

All the above can be either portable or fixed intalation. All you need to do is screw the input onto a tap, waste into a sink or drain and the RO into a bucket, when finished pack it all away but it is important to keep the filters full, easily done by putting a shuttoff valve on each end otherwise drying out will destroy the membrane. To fit a fixed system everything you need usually comes in the kit.
When I first switched my system on I was surprised to see the amount of waste water it was producing ass is sI I decided to measure it. 1 litre of RO produced 3.2 litres of waste, not good even though I do not pay for mine.
I remember reading somwhere that by simply putting a shutoff valve on the waste water outlet and slowly closing it till the RO output starts to decrease you can reduce the waste, apparently closing the valve increases back pressure to a point that its almost as easy to pass through the membrane as it is to go to waste, It takes a bit of patience to get the best result, adjust the valve, wait 30 seconds for result, adjust again, wait, etc., eventually you can almost reduce waste output by half. Sounds great but it has a drawback, it will take longer to make the same amount of water as before so if you are in a hurry just open up full. Since putting on the valve on the discharge for each 1 litre I make I waste between 1.2 and 1.7 litres and i'm slowly getting it down.

A better way to save on waste discharge water and at the same time doubling your production is to add a second membrane filter. To plumb it in you take the waste discharge from the first membrane and plug it into the input of the 2nd membrane, output of this to the waste discharge as before and the new RO output to output of the first membrane giving you double the original output or RO water and still the same amount of discharge as before, then with the valve from the first option tune it for best results.

Depending on which unit you buy ie GPD gallons per day you can also improve things, for example in a 50gpd unit the 75gpd and 100gpd membranes will still fit in the 50gpd membrane housing.

This is just a start to get the ball rolling, I have more mods like taking outputs depending on what water I want but i'de like to hear what mods you's have made to make a simple system better and fit your requirements
I'll also take some photo's and add them to the post.
  • Thread Starter


I have some spare filter housings so if I decide to add a DI unit like you I can but I'm getting 0 tds as is so not worth the expense.

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