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When reverse osmosis filtration systems first hit the market, they came with a storage tank. Its purpose was to store filtered water from the slow filtration process, so you always had a clean supply.
Nowadays, newer tankless models are overtaking the old, thanks to their compact design.
But how can you keep up with a household’s water demand without a water tank? And how does a tankless reverse osmosis system work anyway? Find out here!
So, how does a tankless reverse osmosis system work?
Most tankless RO systems directly connect to the cold water line under the kitchen sink (some also attach to the existing kitchen faucet or are standalone units).
Besides, tankless RO water systems usually have pumps in them. These create pressure that pushes the water through the entire system and out of your faucet in a very short amount of time.
This gives a consistent flow of water on demand and reduces the amount of wastewater that you would find in an RO system without pump significantly.
Some countertop models do not have a pump, so the water pressure will be considerably slower in those.
Tankless and tank RO models more or less filter contaminants just as well as each other. Each type has advantages and disadvantages, but in terms of purifying water, they are pretty much on par.
It really comes down to a personal choice in other areas, such as size, cost, and functionality. Knowing their differences may help determine which is suitable for you and your home.
The main difference between the two types is the size. Tankless RO units are at least 50-75% smaller and easier to move around and install.
Under the sink tank units have the filtration system, plus a 3-gallon (sometimes smaller/larger) storage tank. A tank-based reverse osmosis system needs this as it usually doesn’t have a pump to push the water through the various filter stages and up to the sink faucet; instead, it uses air pressure within the tank to output the water.
Tank RO systems are triggered to filter water and top up the supply when the tank water level lowers and are also triggered to switch off production when the backpressure reaches a certain level, indicating the tank is full.
The other notable difference is that tank RO systems are often standard-sized, meaning they can be modified to include post-filtration steps, such as UV disinfection and remineralization filters, whereas tankless systems often use proprietary sizes and cannot be altered.
We compiled the following list of tankless reverse osmosis system advantages assuming that there is a built-in pressure pump.
Tiny kitchen? No problem. A tankless system won’t take up much space. While the tank models are also highly effective, they really do not do well in small spaces.
RO systems produce waste water and quite a bit of it. There isn’t any getting around it, but you can choose a system that will waste less, and those are often the tankless models.
While tank systems can waste up to 5 gallons of water for each gallon produced, tankless systems can significantly reduce that down to as much as only 0.25 gallons wasted.
The pressure pump in the tankless system is what we have to thank for that. The force they use to push the water through the RO membrane ensures less water is left behind.
Unfortunately, with tank systems, you can’t get in and clean the storage tank. This means there is a chance microorganisms could build up in your tank, re-infecting the purified water. Also, if you let the water sit for too long, even a clean storage tank can leach plastic taste.
Tankless systems eliminate this risk.
The internal pump in a tankless reverse osmosis system means you can filter enough water on demand, unlike with a tank system. You can also filter a higher amount of GPD (gallons per day) than with a tank model.
Tankless systems are easy to install and maintain. Some countertop models, for example, simply need to be plugged in, and you are good to go. Tank systems are more fiddly and harder to maneuver as they are much larger.
They are also harder to maintain as you have to monitor tank pressure and additional valves.
Because of the increased pressure in a tankless RO filter system, it helps to make contaminant reduction slightly more effective, meaning that traces of contaminants left in your water may actually be lower.
Again, we will base the following section on tankless reverse osmosis water filters using an internal pump.
Tank systems sound great, but they may only be suitable for some budgets, as they are usually more costly to purchase.
Tankless systems require electricity to operate, unlike the tank system, which works off plumbing pressure and pressurized air.
Your RO system won’t function if there is a power cut, which leaves you with no access to purified water unless you have some already stored in a container somewhere (we recommend this!)
If your tankless system comes with a pump, or if you have had a pump added, it is much noisier than the tank models.
The design of the system doesn’t allow for customization most of the time, unfortunately.
When trying to determine if an RO system without tank is right for you, here are some questions to ponder;
If you answered yes to all these questions, congratulations, you and the tankless RO system may be a match. Other things to consider when purchasing a unit include the following:
Check your feed water. If you have a lot of sediment or high amounts of a particular contaminant, you may need specialized pre-filters to protect the RO system from damage.
And you want to make sure that, whichever RO system you choose, it’s capable of reducing the specific contaminants found in your water supply.
NSF tests and certificates mean you can rest easy knowing your machine has been vetted and will do everything it says it will do to the appropriate standard. It also indicates the unit is made from high-quality materials.
RO removes all the good minerals from the water as well as the bad stuff. If water without minerals concerns you, consider looking at ways to remineralize your water supply.
Check the expected wastewater output of the unit you want to purchase to ensure it fits your needs. It will be different depending on the manufacturer.
Filters in all reverse osmosis water systems need to be replaced, or the unit just won’t work, and you will have contaminated water. There are various types and sizes of filters, some last longer than others. Also, if you have a lot of contaminants in your water, you will need to replace your filters more regularly.
So this is something to keep in mind as it will also affect operating cost.
If you have any thoughts about the question, how does tankless reverse osmosis work, please don’t hesitate to leave a comment below!
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