Here's a simple explanation: All RO systems are essentially three different parts:
Prefilters, the
Membrane, and a
postfilter/storage tank.
There are usually 2-3
Prefilters: sediment, carbon, and another type of carbon. They just operate with your house's water pressure and are super cheap to change. They remove sediment, metals, and chlorine/chloramine. They're not special filters, you can find tons of parts and replacement filters on amazon for super cheap. It's important to have them clean the water before the next part:
The
RO Membrane actually does the most purification. It has one inlet from the prefilters, and two outlets: one pure water, one wastewater. The wastewater is extremely important as it flushes the junk that would clog the membrane. Most systems have a ratio of 1:2 or 1:4 pure:waste in terms of water, but you can improve that down the line or buy higher-end systems that improve the ratio.
The pure line out from the membrate , then usually to a
Storage Tank. Most systems can hook up to undersink bladder tanks, which are essentially filled with RO water that pushes out like a filled balloon when you turn the little RO faucet on. Some systems will have a post-tank carbon filter to help prevent any bad taste from the storage tank (bladder tanks often taste kinda bad at first!).
Instead of running your pure RO line to
only a storage tank, you can use a 1/4" RO Tee fitting to split the pure RO line to run to a Float Valve in a barrel/bucket nearby to collect large amounts of RO water. This is how most aquarists use RO water AND keep their RO system useable for drinking/cooking!
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I have been using two of these systems for about 5+ years:
For
$170, it has 3 prefilters (sediment, carbon and carbon), a 50-gallon-per-day RO membrane, a 3.2 gallon undersink pressure/bladder tank for drinking water storage, a PAC (post-tank carbon filter) to clean any taste from the bladder tank, and replacements for all of the filters and RO membrane. It's an insane deal and has great reviews for a reason.
The prefilters are standard 10-inch prefilters, so you don't have to get brand-name anything. SUPER cheap replacements are out there. The RO membrane is also the standard 50-gpd membrane size, so you can buy any similar size membrane for crazy cheap.
Produces 1-3TDS water (basically 99.9% purified).
I have one system under my kitchen sink that fills a small drinking/cooking RO water, then has a split for the pure water to fill a 110-gallon RO storage system in my basement that I pump up to my big 140-gallon tank for water changes, as well as for my 40-gallon tank, too. It's been life-changing!
