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Gravity-based water filtration is quite popular among people who want to have a consistent supply of fresh water without having to depend on electricity or water pressure from a plumbing system.
At the same time, reverse osmosis is renowned for its advanced water purification capabilities and thorough operation.
For some people, this leads to the obvious question – is there a device that combines both gravity filtration and reverse osmosis? Like a gravity reverse osmosis water filter?
Unfortunately, there’s no such thing as a reverse osmosis gravity filter on the market.
It doesn’t make sense physically, because reverse osmosis requires high water pressure to work. A gravity-based water filter could theoretically provide that pressure, but in practice, it’s pretty much an unattainable goal.
Don’t believe us? Consider this: A reverse osmosis system requires around 60 psi of feed water pressure for optimal operation, which equates to 60 pounds of pressure per square inch.
Now, 60 pounds of water is equivalent to around 7.2 gallons, which is how much you’d need to store for every square inch of your gravity reverse osmosis water filter. To store that much water over just one square inch, you’ll need a tower that’s more than 1,660 inches in height – or over 138 feet!
Here’s a breakdown of the math in case you are interested:
A gravity water filter uses gravity to pull water between two containers. Water is poured into the top container, from where it naturally makes its way to the bottom one, passing through a single stage or a set of filters along the way. This purifies the water without requiring any additional power or pressure.
Gravity water filters can use a variety of filtration elements to purify the water that passes through them. Some are relatively simple, using a charcoal filter and not much else. Ceramic filter candles are very popular in these devices, and can also be purchased separately for a DIY approach if you want to create your own filter.
Aside from that, gravity-fed filters are available in two main variants – countertop and bag. The former is designed to be used indoors without moving it around much, while the latter is perfect for outdoor use, like camping trips.
On the other hand, a reverse osmosis system uses a very fine, semipermeable membrane, forcing water through it at high pressure. The membrane is fine enough that only water molecules can pass through it (with some minor exceptions), which is where the purification strength of the process comes from. However, for this to work, you need a lot of pressure as we explained above.
This provides one of the most thorough modes of water purification available on the market right now. For this reason, reverse osmosis systems are very popular not just on the consumer market, but also in the industrial sector. Reverse osmosis is the default purification method used in many advanced water facilities.
One disadvantage to reverse osmosis is that it tends to waste a lot of water. Normally, more than 50% of the input water will go to waste. This can be improved first and foremost by adding pressure pumps.
If you have any questions about “gravity-based RO water purifiers” please don’t hesitate to leave a comment below!
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