Who's Thirsty?

Yes, that’s right, I now have very, very clean drinking water. Oh yeah, and water for the aquarium, too! Hehe… Yes, I now have my very own RO/DI water purifier. This is a very good thing from an environmental perspective (I can just see Dave rolling his eyes as he reads that), because it means I will no longer be buying bottled drinking water. It is also a very good thing from an aquarium hobby perspective, because it means that storing water, aging water, and keeping a steady water chemistry in the tank will all be easier now.

Disclaimer: This paragraph is about to be very technical… if you feel your eyes roll into the back of your head, just skip down to the pictures.

So, what is RO/DI? It stands for reverse osmosis/deionization. Osmosis is any transfer through a membrane in the presence of water. Reverse osmosis, is the opposite. It is the transfer of water through a membrane while resisting transfer of other ions. It is about 95-98% effective. That’s where deionization comes in. The remaining ions are attracted to a particular resin that binds the ions while the water passes through. After the DI stage of the device, the water should be 100% pure… but don’t drink it! More on that later…

Here are some pictures:


Here are the hoses leading to and from the basement slop sink and RO/DI (supply/waste). The tubes wrap around the back of the water heater and boiler, along the back wall.

I have the drain line going into a bucket underneath the unit. From the tests I'm running with it, I seem to be able to fill a 5-gal bucket in about an hour.

Here is a front view of the unit. From right to left, the cannisters are a mechanical filter, a carbon filter, a carbon filter geared towards removing chloramine, and the DI unit. The RO unit is on the top of the housing.

Top view of the unit - the cannister is the RO membrane. From top to bottom, the other pieces are the RO only valve, the by-pass valve, and the flush valve. An auto shut-off is underneath the flush valve. The way the flow path runs is through the sponge filter and the two carbon units, then the RO membrane, then the DI resin, and finally out. If you want, you can bypass the DI unit and have RO only water.

Here is the RO only valve. You might be asking why there is an "RO only valve". Basically, the human body can not handle pure water. We will get sick to our stomachs (read: diarrhea). So, the purest we would want our drinking water is RO only. This valve is the feed for drinking water.