Reverse Osmosis Water Filters Buyer's Guide
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  We review, analyze and compare the best water filters in the industry including reverse osmosis systems, faucet filters, water distillers, pitcher filters, whole house filters, water softeners, shower filters, bottled waters and more.

Reverse Osmosis Systems - Myths Explained


There are many online suppliers offering many different styles of reverse osmosis systems- all with different sales pitches. Confused? You bet! Lets discuss some popular myths on RO systems...

Will Reverse Osmosis remove health minerals which my body needs?

This is a common misconception about reverse osmosis water. Tap water may contain a very small amount of minerals, but the quantity is much too small to have an impact on health. For example, one glass of orange juice has more minerals than a bathtub of water. Water also contains only inorganic minerals which our bodies cannot readily absorb and this can cause health problems. Our bodies prefer natural organic minerals which we can only get from the food we eat. Natural rain water has almost no minerals and people have been collecting and drinking it for thousands of years without problems.

The minerals in water also include heavy metals which are sometimes toxic and radioactive. Water systems that don’t remove minerals will also leave these unhealthy metals in your drinking water. Reverse Osmosis removes inorganic minerals, metals and much more to provide you with the purest, healthiest and most natural drinking water.

Does Reverse Osmosis produce a lot of waste water?

A reverse osmosis system does produce some waste water. RO waste water is actually rinse water used to clean and flush the membrane as it filters out water contaminants. This advanced process known as crossflow protects the membrane from clogging and allows it to last for 4-5 years of service before replacement. It also keeps RO systems clean and sanitized as the majority of harmful contaminants are flushed down the drain instead of trapped inside the filter housings. Non-RO water filters do not have this feature and will require costly, troublesome filter replacements and system sanitization every 1-3 months. The long-lasting durability and efficiency of RO systems allows people to save time and hundreds to thousands of dollars on replacement filters over the life of the system.

Most RO systems on the market will have a waste to product water ratio of between 3:1 and 4:1 with an open tank. For systems using a pressure tank, a permeate pump can be easily added to reduce tank back pressure and greatly reduce water usage. Considering the amount of water most families drink a day, the amount of wasted water is typically the equivalent of an extra 4-5 extra toilet flushes a day. RO waste water is fairly clean and can be collected and used for watering plants and other household cleaning applications.

Are smaller micron pre-filters (1 micron) better than 5 or 10 micron prefilters?

Smaller is NOT better in this case! The prefilter's (filters before the RO membrane) function is to pre-treat the water so the membrane can most effectively remove the contaminants. In other words, the reverse osmosis membrane is the hero, not the pre-filters. Using a 1 micron pre-filter will very quickly clog up your system before the dechlorinating ability is used up- so you have to change your pre-filters very frequently!

Secondly, a 1 micron pre-filter before the membrane would cause a big drop in water pressure before water reaches the RO membrane. As we all know, the higher the water pressure, the better the contaminant rejection ability of the RO membrane. So if you want your water to be pure, don't pick a system that's designed with a 1 micron pre-filter. We recommend a 5 micron sediment pre-filter partnered with 5-10 micron carbon filters to provide the maximum lifetime of the pre-filters and RO membrane.

Are plastic pressure tanks better than steel tanks?

NO. Simply put, all first class pressure tanks are steel (metal) pressure tanks. (F.Y.I. water in the tank does not touch the steel. Water is enclosed in a soft bladder, surrounded by air, then enclosed in the steel housing of the tank. Therefore there are no rusting problems.) Metal tanks are superior due to that their air pressure is not easily lost (creeps out) like economic plastic tanks. The only advantage of plastic tanks is that they are light in weight.

Are systems build using ALL inline filters (filters built into filter housing) better than those using big, permanent canister filter housings ?
Absolutely not. These are just untrue advertising claims. Those systems which use cropped-down-sized inline pre-filters should be only used as a portable countertop unit, or used where space is a real issue. They are not designed for heavy duty usage.

The life time of inline filters are much shorter than the classic type filters. Just compare their sizes. The classic type carbon filters has a 3 inch diameter, while the inline type has only less than a 2 inch diameter. The carbon volume in the classic type of filters is much more (almost 2-3 times as much) than those of the inline filters. This makes the classic filters dirt-holding ability and lifespan to be 3-6 times more than those of the economical inline filters.

Proportional size of filter cartridges

Inline filters
Classic carbon filter
Classic filter housings
Inline water filter
Carbon water filter
Water filter housing
1.8 inch diameter
3 inch diameter

Therefore, filter systems that use all inline filters will be very problematic if they are used to treat well water or worse water quality homes. Those filters will clog up prematurely. We have seen those inline filters clogged up in just 2 months under heavier sediment conditions- disregard of the advertised capacity. If the prefilters are exhausted, the reverse osmosis membrane will fail shortly after. Owners of such systems need to constantly monitor and maintain their systems.

Again, the inline filters' advantages are their compact sizes and cheaper costs. So they are still the preferable choice for small/ portable countertop systems.

Some suppliers advertise a 90% inlet water pressure shutoff valve to pair up with their permeate pump- so to allow the highest shutoff pressure in the tank (so the output pressure from the tank is nice.) Is this needed?

No, it is definitely not needed- a useless feature (if you understand how the permeate pump works.) The permeate pump itself already has a build-in shutoff valve that will shut off the system after the tank reaches its maximum possible pressure (about 95% of the inlet pressure). Adding a second shutoff valve on top of a shutoff valve is of no meaning.